JPH0614042Y2 - Deceleration control device for internal combustion engine with supercharger - Google Patents

Description

TECHNICAL FIELD The present invention relates to a deceleration control device for an internal combustion engine with a supercharger including a supercharger such as a turbocharger or a supercharger.

2. Description of the Related Art Turbochargers and superchargers are widely used as superchargers for internal combustion engines for automobiles and the like, but these superchargers are usually arranged upstream of a throttle valve.
When the electronically controlled fuel injection device is used as the fuel supply system of the internal combustion engine, an air flow meter for detecting the intake air amount of the internal combustion engine is arranged upstream of the supercharger.

As disclosed in Japanese Utility Model Laid-Open No. 61-152736, a recirculation valve is provided to return intake air from the downstream side of the turbocharger to the upstream side of the turbocharger in order to prevent surging during engine deceleration. Some have been written.

With the turbocharger arranged upstream of the throttle valve of the internal combustion engine as described above, when the turbocharger is decelerated suddenly from the supercharging range, that is, when the throttle valve is closed, the inertia of the supercharger is reduced. The pressure between the supercharger and the throttle valve rises rapidly due to (which is especially true of turbochargers) and the inertia of the airflow in the intake passage. In other words, more air than the amount of air actually flowing into the engine passes through the air flow meter portion provided in the intake passage. Further, since the air once having a high pressure downstream of the supercharger flows backward, the air flow meter such as a hot wire type also detects this.

Therefore, the air flow meter erroneously detects that the intake air amount is larger than the actual intake air amount, the fuel injection amount calculated based on this is excessive, and the air-fuel ratio becomes rich. Therefore, deterioration of emission and deterioration of drivability due to misfire occur, which leads to so-called engine stall in an extreme case.

FIG. 5 shows, as an example, the engine speed (a) when the speed is rapidly decelerated from the supercharging range to the throttle valve fully closed (idle opening),
It shows changes in the fuel injection amount TP (B) and CO in the exhaust (C), respectively. The amount of air actually taken into the engine is sharply reduced by fully closing the throttle valve. Therefore, originally, the fuel injection amount TP must be sharply reduced as shown by the chain double-dashed line (b '). I won't. However, as described above, the fuel injection amount TP becomes excessively large due to the erroneous detection of the air flow meter, and the air-fuel ratio becomes rich accordingly, so that CO in the exhaust gas increases.

Even if a recirculation valve is provided as in Japanese Utility Model Laid-Open No. 61-152736, the effect of erroneous detection of the air flow meter during deceleration cannot be completely eliminated. Further, if the recirculation valve is provided in this manner, the number of parts is increased and the cost is increased.

Means for Solving the Problems This invention is intended to eliminate the above-described adverse effects at the time of deceleration in a supercharged internal combustion engine without complicating the mechanical structure. As shown, a supercharger 3 arranged upstream of the throttle valve 2 of the internal combustion engine 1,
An air flow meter 4 arranged upstream of the supercharger 3 for detecting the intake air amount of the internal combustion engine 1, a rotation speed sensor 5 for detecting the rotation speed of the internal combustion engine 1, the detected intake air quantity and the rotation speed. In an internal combustion engine with a supercharger, which includes an injection amount calculation means 6 for calculating a fuel injection amount based on the above, a predetermined opening of the throttle valve 2, for example, a fully closed state or a non-fully closed intermediate opening Closing operation detecting means 7 for detecting closing operation
And a storage means 10 for storing the maximum value of the fuel injection amount set in advance corresponding to each engine speed at the predetermined opening.
And a maximum value setting means 8 for sequentially setting a maximum value corresponding to the actual engine speed based on the storage means 10, and a fuel injection amount equal to or less than the maximum value for a predetermined period from the start of the closing operation of the throttle valve 2. It is characterized in that a correction means 9 for limiting the above is provided.

Action When the internal combustion engine 1 is decelerated, its load is relatively small, so the fuel injection amount required at that time becomes small by itself. The maximum value of the fuel injection amount set by the maximum value setting means 8 allows for some margin in the required injection amount that can be predicted during such deceleration, and corresponds to each rotation speed in the storage means 10 in advance. It is given as data.

When the internal combustion engine 1 decelerates, that is, when the throttle valve 2 closes, as described above, the amount of air detected by the air flow meter 4 becomes lower than the true amount of intake air due to the inertia of the supercharger 3 and the inertia of the air flow in the intake passage. However, at this time, the fuel injection amount is limited by the maximum value. This prevents the air-fuel ratio from becoming rich immediately after deceleration.

Embodiment FIG. 2 is a structural explanatory view showing a mechanical structure of an embodiment of a deceleration control device according to the present invention.

In the figure, 11 is an internal combustion engine, 12 is this internal combustion engine 1
1 shows the intake manifold connected to 1. The intake manifold 12 has a collector portion 12b in which each branch portion 12a is assembled, and one end of an intake passage 13 is connected to the collector portion 12b. An air cleaner 14 is provided at the other end of the intake passage 13, and a heat wire type air flow meter 15 for measuring the amount of intake air is mounted downstream of the air cleaner 14.
A throttle valve 16 is provided at the inlet of the collector portion 12b. The throttle valve 16 is equipped with a throttle valve opening sensor 17 such as a potentiometer for detecting the opening, and an idle switch 1 for detecting the fully closed state (idle opening).
8 is installed. The idle switch 18 emits an ON signal when the throttle valve 16 is at the idle opening.

Further, a fuel injection valve 19 is provided in each of the branch portions 12a of the intake manifold 12 toward an intake port to supply fuel to each cylinder.

Reference numeral 20 denotes an exhaust drive type turbocharger as an example of the supercharger. As is well known, the turbocharger 20 includes a compressor 21 and a turbine 22 which are coaxially connected to each other.
The intake passage 13 is located between the throttle valve 16 and the air flow meter 15. Further, the turbine 22 is interposed in the exhaust passage 23 of the internal combustion engine 11. A wastegate valve 24 for bypassing a part of the exhaust gas is provided on the upstream side of the turbine 22 in the exhaust passage 23. The waste gate valve 24 is opened and closed by a diaphragm type actuator 25.
When the supercharging pressure on the downstream side of the compressor 21 reaches a predetermined pressure, the opening operation is performed to release a part of the exhaust gas.

Further, a bypass passage 26 is formed on the downstream side of the intake passage 13 so as to bypass the throttle valve 16 and introduce auxiliary air into the collector portion 12b, and an idle up solenoid 27 is interposed in the bypass passage 26. It is equipped. The idle-up solenoid 27 is composed of a kind of digitally controlled flow control valve, and when the load of the alternator is increased due to lighting of a vehicle headlight or the like, or when the load of a compressor for an air conditioner (air conditioner) is applied. In addition, the auxiliary air is appropriately introduced into the internal combustion engine 11.

Further, 28 is a water temperature sensor for detecting the cooling water temperature of the internal combustion engine 11, 29 is an engine speed sensor for detecting the speed of the internal combustion engine 11, and 30 is a control unit. The control unit 30 is composed of a so-called digital microcomputer, and executes the injection amount control of the fuel injection valve 19 and the flow rate control of the idle up solenoid 27 according to a predetermined program. Detection signals are input to the control unit 30 from sensors such as an air flow meter 15, a throttle valve opening sensor 17, an idle switch 18, a water temperature sensor 28, and an engine speed sensor 29.

In the above configuration, the fuel injection amount supplied from the fuel injection valve 19 to the internal combustion engine 11 is basically based on the intake air amount detected by the air flow meter 15 and the engine speed detected by the engine speed sensor 29. Controlled. Since this injection amount control itself is known, a detailed description thereof will be omitted,
The basic fuel injection amount TP is calculated based on the detected intake air amount and the engine speed, and various increase corrections and corrections to the battery voltage are added to this to determine the final fuel injection amount, that is, the injection pulse width PI. Is done. Therefore, the larger the intake air amount detected by the air flow meter 15, the larger the basic fuel injection amount TP and the actual injection amount TI.
Will also be large.

On the other hand, when the internal combustion engine 11 is decelerated, that is, when the throttle valve 16 is closed, the basic fuel injection amount TP is limited to the maximum value TPMAX or less according to the flowchart shown in FIG. The operation during deceleration will be described below with reference to the flowchart of FIG.

First, in step 1, it is determined whether the cooling water temperature TW of the internal combustion engine 11 at that time is equal to or higher than a predetermined temperature TWTPMX. This is because the increase correction is performed so as to increase the fuel injection amount when the internal combustion engine 11 is at a low temperature. Therefore, when the internal combustion engine 11 is at a low temperature below the predetermined temperature TWTPMX, the basic fuel injection amount TP during deceleration is limited. Does not. If the cooling water temperature TW is equal to or higher than the predetermined temperature TWTPMX, the process proceeds to step 2 and it is determined whether the deceleration operation is performed. Specifically, the opening TVO of the throttle valve 16 is the predetermined opening TPMX.
Whether or not the state above V has changed to the state below
The determination is made from the opening of the throttle valve 16 read last time and the opening of the throttle valve 16 read this time. The above-mentioned predetermined opening degree TPMXV is given in advance in a form corresponding to the engine speed, and the basic fuel injection amount TP is not limited unless the opening degree is reduced to less than this value.

If it is determined in step 2 that the vehicle has decelerated, step 3
Then, it is determined whether the idle switch 18 is ON, that is, whether the throttle valve 16 is closed to the idle opening degree. Here, the throttle valve 16
If the idle opening solenoid 2 has been closed to the idle opening degree, the routine proceeds from step 3 to step 4.
It is determined whether or not 7 is in an OFF state, that is, whether or not auxiliary air introduction is being performed. If a large electric load is not applied and the idle up solenoid 27 is in the OFF state, the process proceeds to step 5 and TPMAXS is set as the maximum value TPMAX of the basic fuel injection amount TP.
Select. This maximum value TPMAXS is preset with a slight margin in the required fuel injection amount that can be predicted under this condition, and is given in the form of a data table with the engine speed as a parameter. A value corresponding to the engine speed at that time is selected from here. Then, based on this maximum value TPMAXS, the basic fuel injection amount T
P is limited.

Therefore, even if the basic fuel injection amount TP calculated from the intake air amount and the engine speed is equal to or more than the above-mentioned maximum value TPMAXS, the actual injection amount control is performed with the maximum value T.
PMAXS will be used, and further parts will be cut.

Then, the limitation of the basic fuel injection amount TP is to start deceleration,
More specifically, the idle switch 18 continues to be turned on until a predetermined time TTOLL has elapsed (step 9). When the predetermined time T STOLL has elapsed, the routine proceeds to step 11, where the restriction on the basic fuel injection amount TP is released. If the throttle valve 16 is opened and the idle switch 18 is turned off before the predetermined time TTOLL has elapsed, the restriction of the basic fuel injection amount TP is also released (steps 10 and 11).

In step 4, the idle up solenoid 27 is turned on.
If it is in the N state, the process proceeds to step 6 and it is determined whether or not the air conditioner is in the OFF state. This is the idle up solenoid 2 depending on whether the air conditioner is on or off.
This is because the auxiliary air flow rate by 7 differs and the required fuel injection amount also differs. Therefore, TPMAXS1 (step 7) or TPMAXS2 (step 8) is selected as the maximum value TPMAX depending on whether the air conditioner is OFF or ON. These maximum values TPMAXS1, TPMAXS2
Is also set according to the engine speed. Incidentally, in these cases as well, the limitation of the basic fuel injection amount TP is executed only during the time period TSHOLL (step 9).

On the other hand, when the throttle valve 16 is closed to an intermediate opening other than idle, the routine proceeds from step 3 to step 12 and thereafter, and the basic fuel injection amount TP is limited accordingly. In step 12, it is determined whether or not the idle-up solenoid 27 is in the OFF state, as in step 4, and in step 14, it is determined whether or not the air conditioner is off, as in step 6. Therefore, there are also three cases depending on the state of the auxiliary air amount, and the maximum value TPMAX is TPXSS (step 1
3), TPXS1 (step 15) and TPXSA (step 16) are selected. These values are also set corresponding to the engine speed. Then, the limitation of the basic fuel injection amount TP using these values is executed only during the predetermined time TSTLL2 (step 17). The elapsed time is measured from the time when the throttle valve opening TVO becomes equal to or less than the predetermined opening TPMXV in step 2. Further, when the internal combustion engine 11 is switched to the acceleration state before the predetermined time TSTLL2 has elapsed, the restriction on the basic fuel injection amount TP is also released (step 18). More specifically, the determination as to whether or not the acceleration has been performed is made based on whether or not the opening degree TVO of the throttle valve 16 has become equal to or larger than the above-described predetermined opening degree TPMXV.

As described above, in the above embodiment, one of the six data tables is selected according to the degree of deceleration, the presence / absence of the auxiliary air amount, and the magnitude thereof, and the maximum value TPMAX corresponding to the engine speed is read from the data table. The basic fuel injection amount TP is limited as a result. Therefore, the maximum value corresponding to each rotation speed can be set without allowing for such a large margin, and the excess fuel injection amount can be cut substantially along the intake air amount actually sucked into the internal combustion engine 11.

Similar to FIG. 5 described above as an example, FIG. 4 shows changes in the engine speed and the like when the throttle valve 16 is suddenly closed from the supercharging region of the turbocharger 20 to the idle opening degree. . In this case, since the basic fuel injection amount TP is limited by the above-mentioned TPMAXS at the same time when the throttle valve 16 becomes the idle opening degree, the basic fuel injection amount T is irrespective of the magnitude of the detected air amount of the air flow meter 15.
P decreases sharply. Therefore, the enrichment of the air-fuel ratio due to the erroneous detection of the air flow meter 15 is prevented, and the deterioration of the emission can be prevented as shown in FIG.

Effect of the Invention As is clear from the above description, according to the deceleration control device for an internal combustion engine with a supercharger according to the present invention, the fuel injection amount is limited to a predetermined maximum value or less during deceleration, that is, when the throttle valve is closed. Therefore, even if the airflow meter erroneously detects the intake air amount more than the actual amount due to the inertia of the supercharger or the inertia of the air flow in the intake passage, the excess injection amount portion will be cut, It is possible to prevent the air-fuel ratio from becoming rich. Therefore, even when a large-capacity turbocharger is used, it is possible to reliably prevent deterioration of emission during deceleration and deterioration of drivability.

In particular, in the present invention, the maximum value is set not in accordance with the constant value but in correspondence with the engine speed, so that it is appropriate in consideration of intake pulsation, wall flow generation state, fuel state, etc., which are different depending on the engine speed. The maximum value can be sequentially given, and the deterioration of the air-fuel ratio can be prevented with higher accuracy.

Moreover, by providing a plurality of storage means respectively corresponding to the fully closed state and the intermediate opening degree as in the fourth aspect, it is possible to suppress the enrichment of the air-fuel ratio even when the deceleration is not reached at the fully closed state.

Further, according to the present invention, it is not necessary to increase the mechanical components, and the invention can be easily applied to various internal combustion engines with a supercharger.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims showing the structure of the present invention, and FIG. 2 is a structural explanatory view showing the mechanical structure of an embodiment of the present invention.
FIG. 3 is a flow chart showing the main part of control in this embodiment, FIG. 4 is a characteristic diagram showing changes in fuel injection amount, etc. during deceleration in this embodiment, and FIG. 5 is a conventional fuel injection amount during deceleration. FIG. 6 is a characteristic diagram showing changes in the above. 1 ... internal combustion engine, 2 ... throttle valve, 3 ... supercharger,
4 ... Air flow meter, 5 ... Rotation speed sensor, 6 ... Injection amount calculation means, 7 ... Closing operation detection means, 8 ... Maximum value setting means, 9 ... Correction means.

Claims (4)

[Scope of utility model registration request] 1. A supercharger disposed upstream of a throttle valve of an internal combustion engine, an air flow meter disposed upstream of the supercharger and detecting an intake air amount of the internal combustion engine, and a rotational speed of the internal combustion engine. An internal combustion engine with a supercharger comprising a rotation speed sensor for detecting and an injection amount calculating means for calculating a fuel injection amount on the basis of the detected intake air amount and rotation speed. A closing operation detecting means for detecting the closing operation, a storage means for storing the maximum value of the fuel injection amount set in advance corresponding to each engine rotation speed at the predetermined opening degree, and an actual engine rotation based on the storage means. A maximum value setting means for sequentially setting a maximum value corresponding to the number, and a correction means for limiting the fuel injection amount to the maximum value or less for a predetermined period from the start of the closing operation of the throttle valve. Internal combustion with supercharger Deceleration control apparatus for a cough. 2. The deceleration control device for an internal combustion engine with a supercharger according to claim 1, wherein the predetermined opening is a fully closed state of the throttle valve. 3. The deceleration control device for an internal combustion engine with a supercharger according to claim 1, wherein the predetermined opening is an intermediate opening that does not reach full closure. 4. The internal combustion engine with a supercharger according to claim 1, wherein a plurality of openings are preset as the predetermined opening, and a plurality of storage means corresponding to the respective openings are provided. Deceleration control device.