JPH0526939B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine control device.

[Prior art]

Recently, in vehicle engines, from the perspective of improving engine drivability, roughness sensors detect the roughness state of the engine, and when roughness occurs, various combustion state control devices that control the combustion state of the engine are used to suppress roughness. There are various ways to control the direction. As an example, conventionally, as shown in Japanese Patent Publication No. 56-33571, the air-fuel ratio of the air-fuel mixture is set to the lean side to cause the engine to perform lean combustion, which improves fuel efficiency and reduces exhaust gas emissions. As a countermeasure, there is a method in which the air-fuel ratio of the air-fuel mixture is corrected to the rich side in accordance with the output of a roughness sensor, thereby suppressing the roughness caused by lean combustion.

In addition, it is generally known that during low-load operation with a small throttle opening, pumping loss increases, leading to a decrease in fuel efficiency. In this case, fuel supply to some cylinders is stopped to perform cylinder reduction operation, and the load on the remaining operating cylinders is relatively increased, thereby lowering the intake negative pressure, that is, approaching atmospheric pressure, and reducing pumping loss. A so-called engine with cylinder number control has been proposed to reduce fuel consumption and improve fuel efficiency. The method of stopping fuel supply in this cylinder number controlled engine is to close the shutter valves installed in the intake passages of some cylinders (shutter valve method), or to keep the intake and exhaust valves of some cylinders fully closed. (valve select method), and there is also a method of stopping fuel injection valves for some cylinders (fuel cut method).

By the way, in the above-mentioned engine with controlled number of cylinders, from the viewpoint of suppressing roughness, it is possible to detect the roughness state and control various combustion condition control devices in the direction of suppressing roughness. How to detect roughness is a very important issue in ensuring good roughness control accuracy.

In other words, in a cylinder number controlled engine, the engine rotational balance is generally maintained based on the all-cylinder operating state, and when operating with fewer cylinders, the rotational balance naturally collapses, and roughness occurs due to the rotational imbalance. However, this roughness cannot be suppressed even by controlling the combustion state. Therefore, in a cylinder number control engine, if control is performed when roughness occurs by simply comparing the output of the roughness sensor with a roughness fixed reference value, as in the conventional device, the above-mentioned rotational balance will be disrupted during cylinder reduction operation. This is because the roughness control becomes overcontrolled by the output of the roughness sensor caused by the roughness sensor.

[Purpose of the invention]

In view of these problems, the present invention provides an engine control device that prevents overcontrol of roughness control during reduced-cylinder operation and efficiently suppresses roughness during both full-cylinder and reduced-cylinder operation. That is.

[Structure of the invention]

Therefore, the present invention corrects the roughness standard value during reduced-cylinder operation to a value larger than that during full-cylinder operation in a cylinder number control engine, and performs roughness control according to the determination result using the roughness determination standard value. This is how it was done.

That is, as shown in the functional block diagram of FIG. 1, in this invention, the operating state of the engine is detected by the operating state detecting means 38, and in response to the output of the detecting means 38, the cylinder number controlling means 39 controls the engine's operating state. During a specific operating state, the fuel supply to some cylinders is stopped to perform cylinder reduction operation, while the roughness sensor 40 detects the roughness state of the engine, and the roughness control means 4
1 compares the output of the roughness sensor 40 with a roughness fixed reference value, and when roughness occurs, controls the various combustion condition control devices 42 that govern the combustion state of the engine in a direction to control the roughness, and at this time corrects the reference value. The means 43 corrects the roughness constant reference value when the engine is operated with reduced cylinders to a value larger than that when the engine is operated with all cylinders.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

2 and 3 show an engine control system according to an embodiment of the present invention. In the figure, 1 is a multi-cylinder engine, in which intake and exhaust passages 2 and 3 of each cylinder of the engine 1 are provided with intake and exhaust valves 4 and 5. A Rocker arm type valve train 6 that opens and closes is provided, and the valve train 6 for a specific cylinder is equipped with a conventionally known fuel supply stop device 7 that stops the operation of the valve train 6 and stops the supply of fuel to a specific cylinder. It is provided.

Further, a throttle valve 8 is provided in the middle of the intake passage 2 of the engine 1, a vane type air flow meter 9 is provided in the intake passage 2 on the upstream side of the throttle valve 8, and an air cleaner is provided at the upstream end of the intake passage 2. 10, and a fuel injection valve 11a of a fuel injection device 11 is provided near the downstream end of the intake passage 2. Further, a catalyst 12 for purifying exhaust gas is interposed in the exhaust passage 3 of the engine 1.

The engine 1 is also provided with an idle rotation control mechanism 13 that controls the idle rotation speed. In this control mechanism 13, a bypass passage 14 is formed in the intake passage 2 by bypassing the throttle valve 8, and a control valve 15 for controlling the amount of air flowing into the passage 14 is interposed in the middle of the bypass passage 14. ing.

In addition, part of the exhaust gas is transferred to engine 1 using EGR.
An EGR device 16 is provided which returns the gas to the intake system. In this EGR device 16, one end of an EGR passage 17 is connected to the exhaust passage 3, and the other end of the EGR passage 17 is connected to the intake passage 2.
An EGR valve 18 is installed in the middle of the passage 17.
Negative pressure or positive pressure is introduced into the EGR valve 18.
A solenoid 19 that opens and closes the EGR valve 18 is provided.

In the figure, 20 is a distributor, 21 is an ignition coil, 22 is a key switch, 2
3 is a starter, 24 is a position sensor for the air flow meter 9, 25 is a negative pressure sensor that detects the intake negative pressure downstream of the throttle, 26 is a throttle opening sensor that detects the opening of the throttle valve 8, and 27 is the engine crank. A rotation sensor detects the engine speed from the angle; 28 is a water temperature sensor that detects the engine cooling water temperature; 29 is a shift position sensor that detects the gear position of the automatic transmission; 30 is a sensor that detects the oxygen concentration in exhaust gas. The O ₂ sensor 31 is a catalyst temperature sensor that detects the temperature of the catalyst 12, 32 is a position sensor for the EGR valve 18, and 33 is a vibration sensor that detects engine vibration, which is a parameter of the roughness state of the engine.

Also, 34 is interface 35, CPU 36
and a memory 37. The memory 37 stores arithmetic processing programs (see FIG. 3) for the CPU 36, and the like. Further, the CPU 36 generates a high voltage in the ignition coil 21 according to the rotation of the engine, thereby controlling the ignition timing, and also controls the EGR device 16 according to the operating state of the engine.
The EGR valve 18 is opened and closed to perform EGR control, and the idle rotation control mechanism 1 is also controlled depending on the engine cooling water temperature, cooler load, electrical load, etc.
The control valve 15 of No. 3 is opened and closed to control the idle rotation speed.

Then, the CPU 36 applies a control signal to the solenoid 7a of the fuel supply stop device 7 according to the cooling temperature and loading condition of the engine, thereby controlling the number of cylinders, and injecting fuel according to the engine speed and intake air amount. Create a pulse and send it to the fuel injector 11
In addition to a, fuel injection amount control is performed by injecting and supplying an amount of fuel according to the operating state.
Further, the CPU 36 performs roughness control that compares the output of the vibration sensor 33 with a roughness determination reference value, increases the fuel injection pulse when roughness occurs, and controls the injection amount from the fuel injection valve 11a in a direction that suppresses roughness. At this time, the roughness determination reference value is set to be larger during reduced-cylinder operation than during full-cylinder operation.

In the above configuration, the water temperature sensor 28 and the throttle opening sensor 26 serve as the operating state detection means 38 shown in FIG. 1, and the vibration sensor 33 serves as the roughness sensor 4 shown in FIG.
0, and the fuel injection device 11 and
The CPU 36 serves as various combustion state control devices 42 shown in FIG. 1, and the fuel supply stop device 7 and the CPU 36 serve as cylinder number control means 39 shown in FIG.
Furthermore, the CPU 36 realizes the functions of the roughness control means 41 and the reference value correction means 43 shown in FIG.

Next, the operation will be explained.

First, the control operation of the fuel injection amount and roughness will be explained using the flowchart of FIG. When the engine starts, the CPU 36 first initializes the system (step 44), then reads input information, that is, signals from the key switch 22 and various sensors 24 to 33 (step 45)), and reads the engine speed and intake air amount. The basic fuel injection amount T is calculated according to the change (step 46), and it is determined whether the engine continues in the same operating range (step 47). If the operating range changes, the basic fuel injection amount T is calculated accordingly. Therefore, the correction value X for the fuel injection amount is set to 0 (roughness 48). Next, the CPU 36 determines whether or not the cylinder reduction operation is in progress (step 49). If the cylinder reduction operation is in progress, the vibration sensor 33
The difference x (=R-r1) between the D-conversion output R and the first roughness judgment reference value r1 is calculated (step 50), while during cylinder reduction operation, the A/D conversion output R of the roughness sensor 33 and From calculating x (=R-r2) with the second roughness judgment reference value rz (>r1) which is larger than the first reference value r1 (step 51), and determining whether the difference x thus obtained is positive or not. It is determined whether roughness is present (steps 52 and 53).

And if roughness does not occur,
The CPU 36 adds a value |x|ΔT corresponding to the size of the difference x to the current fuel injection amount correction value X (step 54), and uses this correction value X (=X+|x|ΔT) to calculate the basic fuel The injection amount T is reduced and corrected to make it the actual fuel injection amount T (= T - In addition to the injection valve 11a, fuel injection is performed (steps 59 and 60). In this way, the first roughness judgment reference value r1 is set during full-cylinder operation, and the second roughness judgment reference value r2, which is larger than the first reference value r1, is set during reduced-cylinder operation.
The presence of roughness is detected using each of these, and if roughness does not occur, the fuel injection amount is gradually reduced and the air-fuel ratio of the mixture is controlled to the lean side.
The engine will run lean burn.

If the fuel injection device 11 occurs while lean combustion is being performed in this way, the CPU 36 determines the A/R of the roughness sensor 33 from the fuel injection amount correction value X.
x between D conversion output R and roughness judgment reference values r1 and r2
(Step 55), the basic fuel injection amount T is corrected to decrease using this smaller correction value X (= 58 to 60), and when the fuel injection amount correction value X becomes negative, the correction value X is set to 0 (steps 56 and 57), and henceforth, fuel injection with the basic fuel injection amount T is performed. When roughness occurs in this way, the actual fuel injection amount is gradually increased in the range below the basic fuel injection amount according to the roughness state, and the air-fuel ratio of the mixture is gradually controlled to the rich side. Roughness is suppressed while lean burn is maintained.

In addition, the CPU 36 applies a control signal to the solenoid 7a of the fuel supply stop device 7 according to the engine cooling water temperature and load condition, and applies a control signal to the solenoid 7a of the fuel supply stop device 7.
The number of cylinders is controlled by starting or stopping the engine, and the ignition timing is controlled depending on the operating condition of the engine.
The control valve 15 of the idle rotation control mechanism 13 performs EGR control, and also controls the engine cooling water temperature, cooler load, electrical load, etc. during idling.
The idle rotation speed is controlled by applying a control signal to the bypass passage 14 to adjust the amount of intake air flowing into the bypass passage 14, but since both operations are the same as those conventionally known, a detailed explanation thereof will be omitted.

In the device of this embodiment as described above, while the engine performs lean combustion, when roughness occurs, the air-fuel ratio of the mixture is corrected to the rich side, so the engine can always be operated at the roughness limit, improving fuel efficiency. Out.

In addition, in this device, the reference value for roughness judgment is changed between the cylinder forming operation and the cylinder reduction operation, so over-control of roughness control during cylinder reduction operation is prevented, and the Roughness can be efficiently suppressed during any operation.

By the way, in the above embodiment, roughness control is performed by setting the roughness judgment standard value during reduced-cylinder operation to be larger than that during full-cylinder operation.
The roughness control during reduced-cylinder operation may not be performed at all, and FIG. 4 is a flowchart of calculation processing according to a second embodiment of the present invention in which roughness control during reduced-cylinder operation is stopped. shows.

That is, in this embodiment, during all-cylinder operation, the occurrence of roughness is detected using the roughness determination reference value r (steps 44 to 46, 49, 47, 48, 61, and 53), and when no roughness has occurred, is the fuel injection amount correction value
By gradually increasing the actual fuel injection amount, the actual fuel injection amount is controlled to a value that is a gradual reduction of the basic fuel injection amount depending on the engine operating condition (step 54,
58 to 60), and when roughness occurs, the actual fuel injection amount can be reduced within the range below the basic fuel injection amount by reducing the fuel injection amount correction value X in a range of 0 or more according to the roughness state. The fuel injection amount is increased according to the roughness state (steps 53, 55 to 57), while during cylinder reduction operation, the roughness control is stopped by setting the fuel injection amount correction value X to 0, and the actual fuel injection amount is adjusted to the basic fuel This is set to the injection amount (steps 49 and 62).

Furthermore, in the first embodiment, control of the fuel injection amount and roughness is started immediately when the number of operating cylinders is changed, but in order to more efficiently prevent overcontrol of roughness control, it is necessary to change the number of operating cylinders. It is desirable to delay the start of control when the number of cylinders in operation is changed, and FIG. 5 shows a flowchart of arithmetic processing according to a third embodiment of the present invention in which the start of control is also delayed when the number of operating cylinders is changed.

That is, in this embodiment, the occurrence of roughness is detected using the first roughness determination reference value r1 during full-cylinder operation, and the second roughness determination reference value r2, which is larger than this during reduced-cylinder operation, to prevent roughness from occurring. If not, the actual fuel injection amount T is controlled to an amount that is gradually reduced from the basic fuel injection amount (T1 or T2) according to the engine operating state and the number of operating cylinders (steps 44 to 46, 81, 63 to 77), when roughness occurs, the actual fuel injection amount T is increased in accordance with the roughness state within a range below the basic fuel injection amount (T1 or T2) (steps 70, 78-80). When the load condition of the engine changes and the engine is changed from all-cylinder operation to reduced-cylinder operation, the second set time n2 starts from the time of the change, and when the engine is changed from reduced-cylinder operation to all-cylinder operation, the change occurs. from the time to the first set time n1,
Each actual fuel injection amount T is the basic fuel injection amount T2 above.
or set to T1 (steps 81-87, 69, 88),
After the set time n2 or n1 has elapsed, the control of the fuel injection amount and roughness described above is started (steps 45-46, 81, 63-80).

In the above embodiment, fuel injection amount control is performed according to the roughness state, but in the present invention, EGR control, ignition timing control, or air-fuel ratio control may be performed according to the roughness state. Furthermore, instead of a vibration sensor, the roughness sensor may be a torque sensor that detects engine torque fluctuations or a rotation sensor that detects rotational fluctuations.

〔Effect of the invention〕

As described above, according to the present invention, in a cylinder number controlled engine, the roughness determination reference value during reduced-cylinder operation is corrected to a value larger than that during full-cylinder operation, and the determination result using the roughness determination reference value is Since the roughness control is performed accordingly, it is possible to prevent over-control of roughness control during cylinder reduction operation, and it is possible to efficiently suppress roughness during both full cylinder operation and cylinder reduction operation.

[Brief explanation of the drawing]

Figure 1 is a functional block diagram showing the configuration of the present invention, Figure 2 is a functional block diagram showing the configuration of the present invention.
The figure is a schematic configuration diagram of an engine control device according to a first embodiment of the present invention, and FIG.
A diagram showing a flowchart of arithmetic processing of the CPU 36,
FIG. 4 and FIG. 5 are diagrams showing flowcharts of the arithmetic processing of the CPU 36 in the second and third embodiments of the present invention, respectively. 38... Operating state detection means, 39... Cylinder number control means, 40... Roughness sensor, 41... Roughness control means, 42... Various combustion length control devices,
43... Reference value correction means, 7... Fuel supply stop device, 11... Fuel injection device, 26... Throttle opening sensor, 28... Water temperature sensor, 33... Vibration sensor, 36... CPU.

Claims (1)

[Claims] 1: an operating state detection means for detecting the operating state of the engine; a cylinder number control means that receives the output of the detection means and causes fuel supply to some cylinders to be stopped in a specific operating state of the engine to perform cylinder reduction operation; Various combustion state control devices that control the combustion state of the engine,
a roughness sensor that detects the roughness state of the engine; a roughness control means that compares the output of the roughness sensor with a roughness determination reference value and controls the various combustion state control devices to suppress roughness when roughness occurs; 1. A control device for an engine, comprising: reference value correcting means for correcting the roughness determination reference value during reduced-cylinder operation to a value larger than the roughness determination reference value during full-cylinder operation.