JPH0550584B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is capable of switching between an all-cylinder operation in which output is output from all cylinders and a reduced-cylinder operation in which output is output only from some cylinders, depending on the operating state of the engine. The present invention relates to a control device for an engine that controls the number of cylinders.

(Prior art) In recent years, there has been a desire to significantly improve fuel efficiency, especially in automobile engines, and for this reason, for example, as shown in Japanese Patent Application Laid-Open No. 57-338, the above-mentioned Engines that control the number of cylinders have appeared in which cylinder operation and cylinder reduction operation can be switched and selected as appropriate. In other words, during high loads such as when starting or driving at high speeds, fuel is supplied to all cylinders and output is output from all cylinders, while during low loads such as when driving at a constant speed or on a steady road,
Fuel efficiency is reduced by cutting off the fuel supply to some cylinders and increasing the filling efficiency to other cylinders.

In this way, the cylinder number control engine is provided with a cylinder number control means for cutting fuel supply to some cylinders and switching to reduced cylinder operation, and
It detects engine operating conditions such as engine speed, throttle valve opening, intake negative pressure, and engine temperature, determines whether or not cylinder reduction operation is to be performed, and outputs this determination result to the cylinder number control means. Equipped with cylinder discrimination means.

By the way, while cylinder number control engines have a great effect on fuel efficiency, when operating with reduced cylinders,
Since the explosion stroke becomes more intermittent, torque fluctuations become larger than during all-cylinder operation, and vibrations due to these torque fluctuations also become larger, causing discomfort to the occupants. In particular, during idling, the above-mentioned vibrations become more noticeable.

(Object of the Invention) The present invention has been made in consideration of the above-mentioned circumstances, and an object thereof is to provide a control device for a cylinder number control engine that suppresses as much as possible the occurrence of vibration during cylinder reduction operation. do.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention has the following structure. That is, as shown in FIG. 1, a cylinder reduction determining means for determining whether or not the cylinder reduction operation region is in which fuel supply to some cylinders is cut off according to the operating state of the engine; and the cylinder reduction determination means. a cylinder number control means that is operated in response to an output from the engine and cuts fuel supply to some of the cylinders; a combustion state adjustment means that adjusts factors governing the combustion state of the engine; and a cylinder reduction determination means. Combustion state correcting means receives the output of the combustion state adjusting means and corrects the combustion state adjusting means so that the maximum torque of the operating cylinder only during idling becomes smaller during reduced cylinder operation than during full cylinder operation. It has a different configuration.

(Example) In Fig. 2, 1 is an engine body, and intake air is supplied from an air cleaner (not shown) to a carburetor 2,
Combustion chamber 5 via intake manifold 3 and intake port 4
from the air cleaner to the intake port 4.
The path up to this point constitutes the intake passage 6.
Further, the exhaust gas from the combustion chamber 5 is discharged into the atmosphere from an exhaust port 7 through an exhaust manifold 8 and the like.

The intake valve 9 that opens and closes the intake port 4 and the exhaust valve 10 that opens and closes the exhaust port 7 are opened and closed at predetermined timing by a valve mechanism. In the embodiment, this valve operating mechanism includes turn springs 11 and 12 that bias the intake and exhaust valves 9 and 10 in the valve closing direction, as well as
A camshaft 13 that is rotationally driven by a crankshaft (not shown), a cam 14 provided on the camshaft, rocker arms 15 and 16, and a tappet 1 that constitutes a swinging fulcrum for the rocker arms 15 and 16.
It is roughly composed of 7 and 18. In the embodiment, the engine main body 1 is for four cylinders, and the ignition order is 1-3-4-2, and the first cylinder and the fourth cylinder are stopped during cylinder reduction operation, i.e., the fuel supply is stopped. is the cylinder to be cut, and for this reason, the tappets 17 and 1 for the 1st and 4th cylinders are cut.
8, valve drive control devices 19 and 20 are attached.

The valve drive control devices 19 and 20 are switched and driven by solenoids 21 and 22, respectively, and when the solenoids 21 and 22 are demagnetized,
When the rocking fulcrums of the tappets 17 and 18 relative to the rocker arms 15 and 16 are at positions displaced downward in the figure, the rocker arms 15 and 16 rock in response to the rotation of the camshaft 13, and the intake and exhaust valves 9 of all cylinders are rotated. , 10 are opened and closed, resulting in all-cylinder operation. Conversely, when the solenoids 21 and 22 are energized, the swing fulcrum can be displaced upward in the figure, and the camshaft 1
3 and the intake/exhaust valves 9, 10 are cut off, resulting in reduced cylinder operation with the intake/exhaust valves 9, 10 of the first and fourth cylinders maintained in the closed state.

The above-mentioned valve drive control devices 19 and 20 themselves are already well known as shown in, for example, Japanese Unexamined Patent Publication No. 52-56212, so detailed explanation thereof will be omitted.

The intake port 4 is provided with a partition wall 23, and the intake manifold 3 is provided with a partition wall 24 that is connected to the partition wall 23. These partition walls 23 and 24 allow at least combustion inside the intake passage 6. The part near the chamber 5 is the primary side intake passage 25 and the secondary side intake passage 26.
It is defined as. This primary side intake passage 25
has a smaller effective opening area than the secondary intake passage 26, and at least a portion near the combustion chamber 5 has a shape called an eccentric swirl port or a helical port. Therefore,
The intake air that has passed through the primary intake passage 25 is made into a swirling flow around the cylinder axis in the combustion chamber 6, or is supplied to the combustion chamber 6 in a state where it has already become a swirling flow. . Also, 2
A sub-throttle valve 27 is disposed in the next intake passage 26 and is connected to the main throttle valve 2 in the carburetor 2.
The intake air controlled by 8 is distributed appropriately to only the primary intake passage 25, or to the primary intake passage 25 and the secondary intake passage 26, depending on the opening degree of the sub-throttle valve 27. It will flow.

The sub-throttle valve 27 is controlled by a negative pressure actuator 29, and this will be explained with reference to FIG. The first negative pressure chamber 3 is connected from above in the figure by two first and second diaphragms 31 and 32 spaced apart from each other.
3, a second negative pressure chamber 34, and an atmospheric chamber 35. This first diaphragm 31 is controlled by a return spring 36 and the second diaphragm 3
2 are each biased downward in the figure by a second return spring 37 whose spring force is weaker than that of the first return spring 36. The second diaphragm 32 is linked to the sub-throttle valve 27 via a rod 38 and a bracket 39 connected thereto, so that when the second diaphragm 32 is located at the lowest position in the figure, the sub-throttle valve Tutle valve 2
7 is fully open, and as the second diaphragm 32 moves upward in the figure, the opening degree of the sub-throttle valve 27 becomes smaller.

The first diaphragm 31 can be displaced upward in the figure until it comes into contact with a stopper 40 fixed to the main body 30, and this stroke is indicated by _l1 in the figure. Further, the second diaphragm 32 can be displaced upward in the figure until the second engagement member 42 fixed thereto comes into contact with the first engagement member 41 fixed to the first diaphragm 31. Indicated by l ₂ . Then, the first engaging member 4
1 and the first engaging member 42, when the first diaphragm 31 moves upward by l ₁ from the illustrated position, the second diaphragm 32
is displaced upward in the figure by l ₁ , and from this state, the second diaphragm 32 is displaced upward in the figure by l ₂
It is now possible to displace only the Incidentally, since the actuator 29 itself is well known, further detailed explanation will be omitted.

The first negative pressure chamber 33 of the actuator 29 is
It is connected to a first negative pressure sensing port 44 of the intake manifold 3 via a signal pipe 43 . Further, the second negative pressure chamber 34 is connected to a first connection port 46a of a three-way electromagnetic switching valve 46 via a signal pipe 45. The second connection port 46b of this electromagnetic switching valve 46
is connected via a signal pipe 47 to a second negative pressure sensing port 48 that opens to the intake passage 6 immediately downstream of the main throttle valve 28 when the valve is closed. The third connection port 46c of the electromagnetic switching valve 46 is opened to the atmosphere, and when the electromagnetic valve 46 is turned on or excited, the switching rotor 46d
is in the position shown in the figure, and the first connection port 46a (second
The negative pressure chamber 34) is communicated with the third connection port 46c (atmosphere), and conversely, when the negative pressure chamber 34) is turned off or demagnetized,
When the switching rotor 46d is rotated 90° counterclockwise in the figure, the first connection port 46a (second negative pressure chamber 34) is connected to the second connection port 46b (second negative pressure sensing port 48). communicate.

Reference numeral 49 in FIG. 2 is a control unit consisting of a microcomputer, and the control unit 49 controls the solenoids 21 and 22 to perform either full-cylinder operation or reduced-cylinder operation depending on the operating state of the engine. Of course, it also controls the electromagnetic switching valve 46 and also controls the fuel injection amount, ignition timing, etc. In the following explanation, the present invention, such as fuel injection, etc. Explanation of parts not directly related to this will be omitted.

The control unit 49 receives the opening degree of the main throttle valve 28 from the throttle sensor 50, the engine coolant temperature as the engine temperature from the coolant temperature sensor 51, and the intake negative pressure sensor 52 provided in the intake passage 6. While the detected intake negative pressure and the engine speed from the ignition coil 53 are input, the control unit 49
From there, output is made to both the solenoids 21 and 22 and the electromagnetic switching valve 46.

In FIG. 2, 54 is a distributor, 55 is a spark plug, and 56 is a battery.

Next, the details of control by the control unit 49 will be explained based on the flowchart shown in FIG.

First, in step 57, initialization is performed and the cylinder number flag is set to 1. When this cylinder number flag is "1", it means full cylinder operation, and when it is "0", it means reduced cylinder operation.

Next, in step 58, the engine cooling water temperature, intake negative pressure, engine speed, and throttle opening are input.

Thereafter, based on the data input in step 58, it is sequentially determined in steps 59 to 61 whether the engine operating state satisfies the conditions for reduced-cylinder operation. In other words, the cooling water temperature is at the set value T ₀ (e.g. 60
℃) (step 59), the engine speed is low (step 60) below the set value _N0 (for example, 2000 rpm), and the engine is running at steady or decelerating speed (step 61). If all conditions are met, the process moves to step 62. Note that whether or not the engine is in an acceleration state is determined by calculating the amount of change in throttle opening per unit time to obtain acceleration, and determining whether or not this acceleration is larger than a set acceleration.

From step 62 above, the cylinder number flag is initialized to be 1 in step 57, so the process first moves to step 63, where it is determined that the intake negative pressure is less than the set value _P4 at high load. It is determined whether or not. Then, the intake negative pressure is the set value P ₄
If the load is larger, the process moves to step 64, where the number of cylinders flag is set to 0.

The transition to step 64 is when all the conditions for reduced-cylinder operation are satisfied, so step 65 is followed by reduced-cylinder operation (in the example, 2-cylinder operation).
An output indicating that the engine should be operated is output, that is, the solenoids 21 and 22 are energized, and cylinder reduction operation is started in which the intake and exhaust valves 9 and 10 of the first and fourth cylinders are maintained in the closed state.

During the cylinder reduction operation, an output is sent to the electromagnetic switching valve 46 in step 66 to turn it on, that is, to energize it.
The first connection port 46a and the third connection port 46c are communicated with each other, and the second negative pressure chamber 34 of the actuator 29 is opened to the atmosphere. As a result, actuator 2
9 is actuated only by the intake negative pressure detected by the first negative pressure sensing port 44, and the stroke amount of the rod 38 changes as shown in FIG.

Note that the stroke of this rod 38 affects the force of the swirl of intake air.
This point will be discussed later.

After this, the process returns to step 58, but if the operating condition of the engine remains the same as described above, the process proceeds to step 62 as described above. Then, in step 62, the step
As a result of the cylinder number flag being set to 0 in step 65 as described above, the process moves to step 67, where it is determined whether the intake negative pressure is lower than the set value _P2 and the load is low. In other words, the intake negative pressure is different during reduced-cylinder operation and during full-cylinder operation, even if the engine speed is the same, and therefore, the conditions for switching to full-cylinder operation during reduced-cylinder operation are different. The intake negative pressure P ₂ used during reduced-cylinder operation is used, and the intake negative pressure P ₄ , which is the condition for switching to reduced-cylinder operation during full-cylinder operation, is used during full-cylinder operation (negative pressure
P ₂ is less than the negative pressure P ₄ ). This prevents frequent switching between reduced-cylinder operation and full-cylinder operation in response to intake negative pressure within a short period of time (hunting prevention).

Here, if the cooling water temperature is lower than the set value T ₀ ,
When the engine speed is higher than the set value N ₀ , when accelerating, when the intake negative pressure is lower than the set value P ₂ (during reduced-cylinder operation) or P ₄ (during all-cylinder operation) and under high load, If any one condition is met, the process moves to step 68, where the cylinder number flag is set to 1, and then, in step 69, an output indicating that all-cylinder operation is to be performed is made. i.e. solenoid 2
1 and 22 are demagnetized, and all-cylinder operation is performed in which the intake and exhaust valves 9 and 10 of all cylinders are opened and closed.

During the all-cylinder operation, step 66 is not performed, and the electromagnetic switching valve 46 is turned off, that is, demagnetized, and its first connection port 46a is communicated with the second connection port 46b. As a result, the actuator 29
both the first and second negative pressure sensing ports 44;
48, the stroke amount of the rod 38 is as shown in FIG.

During all-cylinder operation, the stroke amount of the rod 38 in the actuator 29 changes as shown in FIG. 5 as described above. When fully closed or slightly opened as shown, intake negative pressure is introduced into the second negative pressure chamber 34 and the first negative pressure chamber 33 of the actuator 29 is
As a result, the second diaphragm 32, that is, the rod 38, is displaced upward in the figure by l ₁ +l ₂ . When this rod 38 is displaced upward by l ₁ +l ₂ , the sub throttle valve 2
7 is fully closed, all of the intake air is supplied to the combustion chamber 5 through the primary intake passage 25. As a result, the momentum of the swirl becomes the strongest, the combustion speed becomes faster, and the maximum torque is obtained. Furthermore, when the main throttle valve 28 gradually opens and the second negative pressure sensing port 48 is located upstream of the main throttle valve 28, the transmission of intake negative pressure to the second negative pressure chamber 34 is stopped. , the intake negative pressure is transmitted only to the first negative pressure chamber 33, and the stroke amount of the rod 38 becomes _l1 , which corresponds to the amount of upward displacement of the first diaphragm 31 in FIG. . When the main throttle valve 28 opens almost fully, the magnitude of the intake negative pressure transmitted to the first negative pressure chamber 33 also decreases, and when the main throttle valve 28 is fully open, the stroke amount of the rod 38 decreases. becomes 0. Of course, as described above, as the stroke amount of the rod 38 increases, that is, as the intake negative pressure approaches atmospheric pressure and the engine load increases, the opening degree of the sub-throttle valve 27 also increases. The amount of intake air flowing through the intake passage 26 increases.

On the other hand, during reduced-cylinder operation, the stroke amount of the rod 38 becomes as shown in FIG. 6, as described above. As a result of being released to the atmosphere, even if the main throttle valve 28 is fully closed or only slightly opened, the second diaphragm 32 will only follow the first diaphragm 31 and displace upward in FIG. 3. Therefore, the maximum stroke amount of the rod 38 is only _l1 . That is, since the auxiliary throttle valve 27 is always slightly open, even when the main throttle valve 28 is fully closed and the engine is idling, a portion of the intake air flows into the secondary intake passage 26. As the amount of intake air flowing through the next intake passage 25 decreases, the force of the swirl of the intake air supplied to the combustion chamber 6 becomes weaker.
In comparing Fig. 5 corresponding to full-cylinder operation and Fig. 6 corresponding to reduced-cylinder operation, the difference is that the main throttle valve 28 is close to fully closed, that is, at idle when the intake negative pressure is greater than -520 mmHg. Only. More specifically, the maximum torque of the operating cylinders is made equal during full-cylinder operation and reduced-cylinder operation outside the idle region, while in the idle region, the maximum torque during reduced-cylinder operation is greater than that during full-cylinder operation. be made smaller. As a result, during cylinder reduction operation, vibrations during idling are reduced, and running performance is not deteriorated due to insufficient torque at times other than idling.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

It can be applied not only to 4-cylinder engines but also to other multi-cylinder engines such as 6-cylinder engines, and the number of cylinders to be deactivated is not necessarily half the total number of cylinders, but can be an appropriate number (e.g. In a 6-cylinder engine, 2 cylinders or 4 cylinders can be stopped, etc.).

In order to configure a deactivated cylinder, valve drive control devices 19 and 20 are provided in the valve mechanism, and the camshaft 13
For example, a shutter valve may be provided in the intake passage corresponding to the cylinder to be deactivated to cut off the supply of air-fuel mixture to the cylinder to be deactivated. Good too. Furthermore, in the case where each cylinder is provided with a fuel supply device such as a fuel injection valve individually, the fuel supply from the fuel injection valve to the cylinder to be stopped may be cut off. Often, in this case, intake air may be supplied to the cylinder to be deactivated, or it may be possible to supply no intake air at all. However, it is preferable to also cut off the intake air supply to the cylinders to be deactivated in order to reduce so-called pumping loss and further improve fuel efficiency.

The control unit 49 is an analog type,
It can be constructed by any digital computer.

The combustion rate may be slowed down by delaying the ignition timing. However, adjusting the combustion speed based on the momentum of the swirl makes it easier to shift the combustion speed from the maximum torque generation point without greatly reducing efficiency.

To adjust the momentum of the swirl, it is not necessary to divide the intake passage into a primary intake passage and a secondary intake passage; for example, a deflection plate may be placed in the intake passage to deflect the While the intake air is directed in the cylinder tangential direction by the deflection action of the plate, during cylinder reduction operation, the direction of the deflection plate may be changed to weaken the above-mentioned directing action. Alternatively, a device such as that disclosed in Japanese Patent Application Laid-Open No. 74021/1982 may be used to generate swirl and adjust the momentum of this swirl.

(Effect of the invention) In the present invention, when the cylinder reduction operation is performed,
It is possible to reduce vibrations at idle while preventing deterioration of running performance at times other than idle.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the present invention. FIG. 2 is an overall system diagram showing one embodiment of the present invention. FIG. 3 is a detailed sectional view of the main part of FIG. 2. FIG. 4 is a flowchart showing an example of control contents of the present invention. FIG. 5 and FIG. 6 are diagrams schematically showing an example of control contents of the present invention. 1...Engine body, 9...Intake valve, 10...
Exhaust valve, 19, 20...Valve drive control device, 21,
22... Solenoid, 25... Primary side intake passage,
26... Secondary intake passage, 27... Sub-throttle valve, 29... Actuator, 46... Solenoid switching valve, 49... Control unit.

Claims (1)

[Scope of Claims] 1. A cylinder reduction determining means for determining whether or not the cylinder reduction operation region is in which fuel supply to some cylinders is cut off according to the operating state of the engine; a cylinder number control means that is operated in response to an output and cuts fuel supply to some of the cylinders; a combustion state adjustment means that adjusts factors governing the combustion state of the engine; and an output from the cylinder reduction determination means. and a combustion state correcting means that controls the combustion state adjusting means so that the maximum torque of the operating cylinder is smaller during reduced-cylinder operation than during full-cylinder operation only during idling. A control device for an engine that controls the number of cylinders.