JPH0319370B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine cylinder number control device.

In general, an engine cylinder number control device does not require a large engine output in low-load operating ranges such as idling or low-speed driving, so one of the several The system stops the operation of some of the cylinders in the engine and causes the engine to operate with fewer cylinders. Conventional cylinder number control devices, for example, stop the generation of injection pulses applied to the fuel injection valves of cylinders that should be deactivated during low-load operation in engines equipped with fuel injection valves, and As shown in Japanese Unexamined Patent Publication No. 118623/1983, a shutter valve is provided in advance at the intake port of the cylinder to be deactivated, and the shutter valve is closed during low-load operation, thereby reducing the amount of fuel. The supply is stopped to stop cylinder operation.

However, with conventional cylinder number control devices, when switching from all-cylinder operation to reduced-cylinder operation, for example, when switching from 4-cylinder operation to 2-cylinder operation in a 4-cylinder engine, the conventional cylinder number control device simply controls the supply of fuel to the cylinders that should be stopped. Since the engine is stopped, two cylinders suddenly stop operating, resulting in sudden fluctuations in engine torque, resulting in torque shock and deteriorating drivability.

This invention was made in view of the problems of the conventional ones as described above.In an engine that performs reduced-cylinder operation during low-load operation, there is a pause that should be stopped when switching from all-cylinder operation to reduced-cylinder operation. By gradually reducing the amount of fuel supplied to the cylinder to a predetermined amount, for example, to the amount just before a misfire, and then stopping the fuel supply to the idle cylinder, at the time of the switching,
The torque of the deactivated cylinder that should be deactivated is smoothly reduced to greatly reduce the occurrence of torque shock, and the intake passage of the deactivated cylinder is blocked immediately before a misfire occurs to avoid the occurrence of a misfire. The purpose of this invention is to provide a cylinder number control device for an engine.

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

FIG. 1 shows an engine cylinder number control device according to an embodiment of the present invention. In the figure, 1 is an engine, and the engine 1 has four cylinders numbered 1 to 4 from the right side to the left side in FIG. The upper ends of the intake manifolds 2a to 2d are connected to the intake passage 2, and the lower ends of the exhaust manifolds 3a to 3d are connected to the exhaust passage 3. First to fourth fuel injection valves 4a to 4d are provided in each of the intake manifolds 2a to 2d, and second and third fuel injection valves 4a to 4d are provided in each of the intake manifolds 2a to 2d.
Shutter valves 5a and 5d for opening and closing the intake manifolds 2b and 2c of the cylinders are arranged, and in this embodiment, these constitute an intake passage blocking mechanism. Further, the intake passage 2 is provided with a throttle valve 6, and an air flow meter 7 is provided upstream of the intake passage 2.

In the figure, 8 is a rotation sensor that detects the engine speed, and 9 is a throttle sensor that detects the opening degree of the throttle valve 6. In this embodiment, these are used to detect the low-load operating state of the engine. It has become a driving sensor. Reference numeral 10 receives the outputs of the air flow meter 7, rotation sensor 8, and throttle sensor 9, and when the engine load exceeds a set value, sends an injection pulse signal with a pulse width corresponding to the intake air amount to each fuel injector 4a to 4d. In addition, the control circuit 10 stops generating the injection pulse signal applied to the second and third fuel injection valves 4b and 4c when the load is below a set value, that is, during low-load operation. When switching from to two-cylinder operation, the pulse width of the injection pulse signal applied to the second and third fuel injectors 4b and 4c is gradually reduced to a pulse width on the verge of misfire, and then the generation of the injection pulse signal is stopped. When the engine stops, a shutter valve control signal is generated, and when switching from two-cylinder operation to four-cylinder operation, the pulse width of the injection pulse signal is gradually increased, and then the generation of the shutter valve control signal is stopped. I'm starting to do that. 11 receives the shutter valve control signal and operates the shutter valve 5.
This is a shutter valve drive circuit that closes valves a and 5b.

FIG. 2 shows a detailed circuit configuration of the control circuit 10, in which numerals 7, 8, 9, and 11 are the above-mentioned air flow meter, rotation sensor, throttle sensor, and shutter valve drive circuit. In the control circuit 10, 12 receives the output of the air flow meter 7 and calculates the fuel injection amount according to the intake air amount. 13 normally passes the signal a of the injection amount calculation circuit 12 as is. While the cylinder reduction operation signal b is being received, the signal a of the arithmetic circuit 12 is decreased with a predetermined time constant, and when the cylinder reduction operation signal b is being received, the shutter valve control signal d, which will be described later, is reduced. 14 and 15 receive the output of the injection amount calculation circuit 12 or the output of the injection amount correction circuit 13, and generate an injection pulse signal with a pulse width corresponding to the magnitude of the output. These are first and second injection valve drive circuits that are applied to the first, fourth, second, and third fuel injection valves 4a, 4d, or 4b, 4c.

16 receives both the outputs of the rotation sensor 8 and the throttle sensor 9, and depending on the engine load condition,
A cylinder number determination circuit that determines whether cylinder operation or two-cylinder operation should be performed, determines that two-cylinder operation should be performed during low-load operation, and generates a cylinder reduction operation signal b; 17 is the injection amount correction described above; This is a misfire possibility detection circuit that compares the output c of the circuit 13 with a set value to detect the possibility of misfire occurrence, and here, the circuit 17 constitutes a misfire possibility detection means that detects the possibility of misfire occurrence. . Reference numeral 18 generates a shutter valve control signal d when it receives both the outputs from the cylinder number determining circuit 16 and the misfire possibility detecting circuit 17, and after a predetermined time T has elapsed since it no longer receives the output b from the cylinder number determining circuit 16. This is a shutter valve control circuit that later stops generating the shutter valve control signal d.

Next, the operation will be explained using FIG. Here, FIG. 3 is an explanatory diagram of the operation of this device, and FIG. 3 a, b, c, and d are respectively the judgment state of the cylinder number judgment circuit 16, the temporal change in the output of the injection amount correction circuit 13, and the misfire. It shows temporal changes in the output of the possibility detection circuit 17 and the open/close states of the shutter valves 5a and 5b.

During engine operation, when the throttle valve 6 rotates in accordance with the amount of depression of the accelerator pedal (not shown), air is drawn into the intake passage 2 in an amount corresponding to the opening degree of the throttle valve 6. The air is distributed and guided through the intake passage 2 to the intake manifolds 2a to 2d of each cylinder, and at this time, the air flow meter 7 detects the amount of intake air. When the engine load is higher than the set load, in the control circuit 10, the injection amount calculation circuit 12 receives the output of the air flow meter 7 and calculates the fuel injection amount, and the output a of the calculation circuit 12 is the first injection amount. In addition to being added to the valve drive circuit 14,
The injection pulse signal is applied to the second injection valve drive circuit 15 via the injection amount correction circuit 13, and both drive circuits 14 and 15 output an injection pulse signal with a pulse width corresponding to the intake air amount to the first, first and second injection valve drive circuits.
Fuel injection valves 4a for the fourth cylinder and the second and third cylinders;
In addition to 4d, 4b, and 4c, each fuel injection valve 4a~
4d injects fuel. This injected fuel is mixed with the air in the intake manifolds 2a to 2d to form an air-fuel mixture with a predetermined air-fuel ratio, which is taken into each cylinder, ignited by a spark plug (not shown), and combusted. When the load on the engine is large as described above, all four cylinders of the engine are operated to perform all-cylinder operation.

Further, when the load becomes less than the set load while the engine is operating, that is, when the engine enters a low-load operating state, the control circuit 10 controls the number of cylinders determining circuit 1.
6 receives the outputs from both the rotation sensor 8 and the throttle sensor 9, determines that two-cylinder operation should be performed (see A in FIG. Add cylinder reduction operation signal b. Then, the injection amount correction circuit 13 corrects the signal a of the injection amount calculation circuit 12 so that it gradually decreases with a certain time constant (see FIG. 3b), and adjusts the injection pulse signal from the second injection valve drive circuit 15. The pulse width of
The air-fuel ratio of the air-fuel mixture taken into the cylinder gradually becomes leaner, and the torque of the second and third cylinders becomes smaller. When the air-fuel ratio of the air-fuel mixture becomes lean near the limit for misfire occurrence, the misfire possibility detection circuit 17 determines that there is a risk of misfire occurrence based on the magnitude of the output c of the injection amount correction circuit 13, and the shutter valve control circuit 18 The control circuit 18 applies a shutter valve control signal d to the injection amount correction circuit 13 to make the output c of the circuit 13 zero, and the second injection valve drive circuit 15 Generation of injection pulse signals for 4b and 4c is stopped. At the same time, the shutter valve control circuit 18 sends the shutter valve control signal d to the shutter valve drive circuit 11.
In addition, the shutter valves 5a and 5b close the intake manifolds 2b and 2c of the second and third cylinders (see FIG. 3d). As a result, the second and third cylinders stop operating, and the engine performs reduced-cylinder operation with only the first and fourth cylinders.

Further, when the engine load increases and exceeds the set load while the engine is performing the cylinder reduction operation in this manner, the cylinder number determination circuit 16 stops generating the cylinder reduction operation signal b (the cylinder number determination circuit 16 stops generating the cylinder reduction operation signal b). (See B in Figure 3a),
The injection amount correction circuit 13 starts outputting the signal a from the injection amount calculation circuit 12, and gradually increases the magnitude of the signal. Then, the second injection valve drive circuit 15 again generates an injection pulse signal to be applied to the fuel injection valves 4b, 4c, and gradually increases the pulse width, and the injection valves 4b, 4c start injecting fuel. Increase injection amount. Then, when time T has passed since the cylinder reduction operation signal b disappears, the injection valve 4
The injection pulse signals applied to ports b and 4c have returned to a pulse width corresponding to the amount of intake air, and the shutter valve control circuit 18 has a shutter valve control signal d.
The shutter valve drive circuit 11
Open the shutter valves 5a and 5b (Fig. 3d)
), the second and third cylinders start operating, and the engine returns from reduced-cylinder operation to full-cylinder operation.

In the device of this embodiment as described above, the amount of fuel supplied to the cylinders that should be stopped when switching from four-cylinder operation to two-cylinder operation is gradually reduced.
The engine torque decreases smoothly, the occurrence of torque shock is greatly reduced, and problems such as deterioration of drivability do not occur.

Additionally, when switching from all-cylinder operation to reduced-cylinder operation, the risk of misfire is detected, and immediately before a misfire occurs, the intake manifold of the idle cylinder is closed by a shutter valve, making it possible to avoid misfire. .

Furthermore, if air is sucked into a deactivated cylinder during cylinder reduction operation of the engine, the piston of the deactivated cylinder will compress the intake air during its compression stroke, which will reduce engine output. In this device, the shutter valve prevents air from being sucked into the idle cylinder during cylinder reduction operation, thereby preventing a drop in engine output.

Additionally, if fuel injection and shutter valve opening are started at the same time when switching from reduced-cylinder operation to all-cylinder operation, the amount of fuel adhering to the inner wall of the intake manifold of the idle cylinder will be reduced during reduced-cylinder operation. At the beginning of fuel injection, much of the injected fuel adheres to the inner wall of the intake manifold and is not inhaled into the cylinder, resulting in a lean air-fuel ratio and deterioration of the engine's output characteristics. . However, with this device, when switching from reduced-cylinder operation to full-cylinder operation, the shutter valve opening operation is delayed from the start of fuel injection, so the intake of the air-fuel mixture into the cylinders is delayed. When this happens, a sufficient amount of fuel has already adhered to the inner wall of the intake manifold, so the air-fuel ratio of the air-fuel mixture will not become lean, and deterioration of the engine's output characteristics can be prevented. Especially when accelerating, excellent acceleration response can be obtained.

Figures 1 and 2 show the case where the cylinder number control device is configured by a hardware circuit, and Figure 4 is a flowchart of the calculation processing of the CPU in another embodiment in which the device is configured using a microcomputer. The subflow of calculation processing for performing cylinder reduction operation is shown below. Note that other parts of the processing flow, such as the flow for creating an injection pulse signal, the flow for controlling the first and fourth cylinders, etc., are well known, and their explanation will be omitted.

In Fig. 4, 20 is a step for reading the outputs of the rotation sensor 8 and the throttle sensor 9, 21 is a step for determining whether or not the number of cylinders should be changed based on the read outputs of both sensors 8 and 9, and 22 is the number of cylinders. A determination step 23 determines whether or not the change is from 4 cylinders to 2 cylinders. Step _4c corrects the pulse widths _{T 2} and _{T 3} of _the injection pulse signal added to the injection pulse signal to be smaller by a predetermined amount α. Therefore, the step 25 is to make the fuel injection valves 4b and 4c inject fuel, and 25 is a pulse such that the corrected pulse width T ₂ 3T ₃ becomes the set value β, for example, the air-fuel ratio of the air-fuel mixture becomes the air-fuel ratio at the misfire occurrence limit. In the determination step 26, the shutter valves 5a and 5b are closed, and the fuel injection valves 4 of the second and third cylinders are closed.
This step is to stop the operations of b and 4c. Also
27 is a step for causing the second and third fuel injection valves 4b and 4c to inject fuel according to the injection pulse signal read out according to the output of the air flow meter 7, and 28 is a step for starting fuel injection. A determination step 29 is a step for determining whether or not a predetermined time T has elapsed since then, and a step 29 is a step for causing the shutter valves 5a and 5b to perform an opening operation.

Next, the operation will be explained.

While the engine is running, when the CPU reaches step 20 of the subflow, the CPU reads the outputs of both the rotation sensor 8 and the throttle sensor 9 in step 20, and proceeds to step 21, where it reads the outputs of both sensors 8 and 9. The load condition of the engine is judged and it is judged whether the number of cylinders to be operated should be changed or not. If it is judged that the number of cylinders to be operated should not be changed, this subflow is exited as is.

If it is determined that the number of cylinders to be operated should be changed, the CPU proceeds to step 22 and changes the number of cylinders to 4 depending on whether the engine is in a low load operating state.
It is determined whether or not to change from cylinder operation to two-cylinder operation. If changing from four-cylinder operation to two-cylinder operation, steps 23, 24, and 25 are followed. Then, in step 23, the fuel injection valves 4b and 4c of the second and third cylinders are
Pulse width T ₂ , T ₃ of the injection pulse signal added to is reduced by a predetermined amount α, T ₂ = T ₂ − α, T ₃ = T ₃
-α and using the injection pulse signal corrected in step 24, the second and third fuel injection valves 4b, 4c are
inject fuel, and determine whether the pulse widths T ₂ and T ₃ corrected in step 25 are equal to or less than a predetermined value β,
If the pulse widths T ₂ and T ₃ are larger than the predetermined value β, the process returns to step 23 and the correction of the pulse widths T ₂ and T ₃ of the injection pulse signal is repeated to gradually increase the amount of fuel supplied to the second and third cylinders. We will reduce it. Then, the pulse widths T ₂ and T ₃ of the injection pulse signal are set to a predetermined value β
If the conditions are as follows, proceed to step 26, close the shutter valves 5a and 5b, and at the same time stop the operation of the fuel injection valves 4b and 4c of the second and third cylinders to exit this subflow.

Conversely, when changing from 2-cylinder operation to 4-cylinder operation, the CPU goes from step 22 to steps 27, 28,
29, and the pulse widths T ₂ and T ₃ read out according to the output of the air flow meter 7 in step 27.
Fuel injection valves 4b, 4c using the injection pulse signal of
Then, in step 28, it is determined whether a predetermined time T has elapsed since the start of fuel injection. Before the predetermined time T elapses, step 27
The process returns to step 2 and repeats fuel injection, and when the predetermined time T has elapsed, the process proceeds to step 29, where the shutter valves 5a and 5b are opened and this subflow is exited.

In the above embodiment, the cylinder number control device for a four-cylinder engine has been described, but the number of cylinders in the engine may be greater or less than four. Furthermore, when switching from reduced-cylinder operation to full-cylinder operation, fuel injection and opening of the shutter valve may be started simultaneously.

Further, in the above embodiment, a cylinder number control device for an engine equipped with a fuel injection valve was explained, but the present invention can be similarly applied to an engine equipped with a carburetor. The shutter valve may be closed gradually when switching from full-cylinder operation to reduced-cylinder operation. Further, as the flowchart of the processing procedure of the CPU in the control circuit, a flow different from the flow shown in FIG. 4 may be used as long as it achieves the same function.

As described above, according to the present invention, in an engine cylinder number control device that performs reduced-cylinder operation during low-load operation, the amount of fuel supplied to the cylinders that should be stopped when switching from all-cylinder operation to reduced-cylinder operation is controlled. After the amount of fuel is gradually reduced to a predetermined amount, the supply of fuel to that cylinder is stopped, so when switching from full-cylinder operation to reduced-cylinder operation, the engine torque is smoothly reduced and torque shock occurs. This has the effect of eliminating problems such as deterioration of drivability.

Additionally, when switching from all-cylinder operation to reduced-cylinder operation, the system detects the possibility of a misfire occurring in a dormant cylinder, and immediately before a misfire occurs, the intake passage of the dormant cylinder is shut off to cut off fuel supply to that cylinder. Therefore, there is an effect that the occurrence of misfire can be avoided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an engine cylinder number control device according to an embodiment of the present invention, FIG. 2 is a circuit diagram of the above device, and FIGS. 3 a to 3 d are diagrams for explaining the operation of the above device. Yes, Fig. 3a shows the cylinder number judgment circuit 1.
6, FIG. 3b is a diagram showing temporal variations in the output of the injection amount correction circuit 13, and FIG. 3c is a diagram showing temporal variations in the output of the misfire possibility detection circuit 17. FIG. 3d is a diagram showing the open and closed states of the shutter valves 5a and 5b, and FIG. 4 is a diagram showing another embodiment of the present invention configured using a microcomputer.
FIG. 3 is a diagram showing a flowchart of CPU arithmetic processing. 1... Engine, 5a, 5b... Shutter valve (intake passage blocking mechanism), 8, 9... Rotation sensor, throttle sensor (motion sensor), 10...
Control circuit, 17... Misfire possibility detection circuit (misfire possibility detection means).

Claims (1)

[Scope of Claims] 1. An operation sensor that detects the low-load operating state of the engine, and a function that receives the output of the operation sensor and causes the engine to perform reduced-cylinder operation, and switches from all-cylinder operation to reduced-cylinder operation. A control circuit that gradually reduces the amount of fuel supplied to a deactivated cylinder that is to be deactivated at certain times to a predetermined amount and then stops the supply of fuel to the deactivated cylinder; and a control circuit that detects the amount of fuel supplied to the deactivated cylinder at the time of the switching. a misfire possibility detection means for detecting the possibility of a misfire occurrence; and an intake passage blocking mechanism configured in the intake passage of the inactive cylinder for blocking the intake passage, and immediately before a misfire, the inactive cylinder An engine cylinder number control device characterized by cutting off fuel supply to the engine.