JP2001073821A - Internal combustion engine with cylinder cut-off function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine with cylinder cut-off function which can improve fuel consumption performance while increasing the number of cutting off cylinders to the utmost and suppressing deterioration of the engine, extend maintenance intervals while eliminating partial deterioration between the cylinders, and suppress a running cost to the utmost. SOLUTION: Maintenance factors each composed of spark ignition number of cylinders and actuation time accompanied with combustion is integrated by an integration means 160, and compared to each other by a comparison means. When the number of actuated cylinder is set for decreasing according to the load condition by an actuation cylinder number setting means 164, cut-off priority order in the actuated cylinders is determined by a resting cylinder selection means 166 based on the comparison result from the comparison means. The cylinder to be rested is determined according to the resting cylinder priority order. When the number of the actuated cylinder is set for increasing according to the load condition, re-actuation priority order in the cut-off cylinders is determined by the re-actuation cylinder selection means 166 based on the comparison result.

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 cylinder deactivation function, and more particularly, to a cylinder deactivation and return cylinder control of a stationary internal combustion engine used for an air conditioner or the like.

[0002]

2. Related Art In recent years, air conditioners and the like having a configuration in which a compressor is driven by an internal combustion engine have been developed and put into practical use mainly for large buildings. Also in a stationary internal combustion engine used for such an air conditioner or the like, it is desired to improve the fuel efficiency of the internal combustion engine as much as possible.

In this regard, on the other hand, in a multi-cylinder spark ignition type internal combustion engine mounted on a vehicle, the supply of fuel to some of the cylinders is stopped in accordance with the load for the purpose of improving fuel efficiency. An internal combustion engine with a cylinder stop function having a configuration in which spark ignition in the cylinder is stopped to halt combustion has been developed, and it is conceivable that the internal combustion engine with the cylinder stop function is also applied to the stationary internal combustion engine. ing.

[0004]

Generally, in a spark ignition type internal combustion engine comprising a plurality of cylinders mounted on a vehicle,
The combustion order of the cylinders and their combustion intervals are set in advance so that each cylinder operates smoothly continuously at predetermined time intervals, thereby realizing a highly quiet internal combustion engine with less vibration and noise. Is planned. Therefore, simply stopping any one of the cylinders in such an internal combustion engine will cause irregularities in the combustion intervals and generate vibrations and noises. is not.

Therefore, in an internal combustion engine having a cylinder deactivation function mounted on a vehicle, an optimal combination of the number of cylinders that can be deactivated and the cylinder to be deactivated is naturally determined so that even if the cylinder is deactivated, the combustion interval does not become uneven. It is decided. However, if the number of cylinders that can be deactivated is predetermined in this way, even during deactivation, only a predetermined number of cylinders are always deactivated and the remaining cylinders continue burning. Deterioration of some of the remaining cylinders that continue to burn (deterioration of pistons, spark plugs, etc.)
However, there is a problem that only one of them proceeds unevenly.

In particular, a stationary internal combustion engine used in the air conditioner or the like is usually installed together with a compressor as an outdoor unit on a rooftop of a building or the like, and therefore requires regular maintenance by a specialist. However, if only the deterioration of some of the cylinders progresses in a biased manner in the stationary internal combustion engine in this way, the maintenance interval must be shortened and the frequency of maintenance must be increased, resulting in increased maintenance costs. It is not preferable. Further, in general, at the time of the maintenance, since the degree of deterioration of the deactivated cylinder is not accurately known, the deactivated cylinder is the same as the degraded cylinder even though it is still sufficiently durable. In many cases, measures (such as replacement of a spark plug) are performed, which also causes an increase in maintenance cost.

Further, in the stationary internal combustion engine used in such an air conditioner or the like, unlike the internal combustion engine mounted on a vehicle, economy is given priority over riding comfort. Therefore, in such a stationary internal combustion engine, it can be said that it is preferable to freely select the number of cylinders to be deactivated and the cylinder to be deactivated simply in accordance with the load in order to improve fuel efficiency and prevent deterioration.

The present invention has been made in view of the above circumstances, and an object of the present invention is to increase the number of cylinders to be closed as much as possible to achieve a dramatic improvement in fuel efficiency and suppression of deterioration of an internal combustion engine. It is an object of the present invention to provide a stationary internal combustion engine with a cylinder rest function, which can extend the maintenance interval by eliminating the bias of deterioration among the cylinders and reduce the running cost as much as possible.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, in a multi-cylinder spark ignition type internal combustion engine with a cylinder deactivation function, the number of operating cylinders is set according to the load state. Means for setting the number of operating cylinders to be operated, integrating means for setting the number of times of spark ignition of each cylinder or operating time accompanying combustion as a maintenance factor, and integrating the maintenance factor for each cylinder, and storing the integrated value by the integrating means. Means, comparison means for comparing the integrated values of the cylinders stored in the storage means with each other, and when the number of operating cylinders is set to the reduced side by the number of operating cylinder setting means, the operating means is operated based on the comparison result of the comparison means. When the number of operating cylinders is set to be increased by the cylinder selecting means for determining the cylinder priority order of the operating cylinder and selecting the cylinder to be capped according to the cylinder priority order, and the operating cylinder number setting means. Return cylinder selecting means for determining a cylinder priority in a cylinder in a cylinder stop based on the comparison result of the cylinders, and selecting a cylinder to be returned according to the cylinder priority, It is characterized by comprising control means for controlling at least fuel supply and execution of spark ignition of each cylinder in accordance with the return cylinder information from the return cylinder selecting means.

Therefore, according to the present invention, the maintenance factor including the number of spark ignitions or the operation time accompanied by combustion of each cylinder is integrated for each cylinder by the integration means, stored in the storage means, and stored in the storage means by the comparison means. Each integrated value is compared with each other. When the number of operating cylinders is set to a decreasing side, that is, a side in which the number of cylinders to be deactivated increases by the operating cylinder number setting means, the deactivated cylinder priority among the operating operating cylinders based on the comparison result of the comparing means. Is determined by the cylinder selection means, the cylinders to be cylinder-stopped are selected in accordance with the cylinder priority, and the control means controls at least fuel supply and spark ignition of each cylinder. On the other hand, when the number of operating cylinders is set to an increasing side, that is, a side where the number of cylinders to be deactivated is reduced by the operating cylinder number setting means, the return cylinder priority order among the deactivated cylinders is also based on the comparison result of the comparison means. Is determined by the return cylinder selecting means, and the cylinder to be returned is selected according to the return cylinder priority order, and the control means controls at least fuel supply and spark ignition of each cylinder.

Thus, the optimum number of operating cylinders is set according to the load condition, the number of cylinders to be deactivated is increased as much as possible, so that it is possible to improve fuel efficiency and suppress deterioration of the internal combustion engine. At times, the most effective cylinder for the cylinder at that time is selected as the cylinder to be preferentially closed according to the integrated value of the maintenance factor, i.e., the number of spark ignitions or the operation time accompanied by combustion, while the cylinder that has been deactivated is selected. When returning
Again, the cylinder most effective for the cylinder at that time is selected as the cylinder to be preferentially restored according to the integrated value of the maintenance factor, thereby preventing the bias of deterioration among the cylinders, that is, the degree of deterioration of each cylinder is equalized. Therefore, the maintenance interval can be extended by minimizing the frequency of maintenance as much as possible, and the running cost can be reduced as a whole.

In the invention of claim 2, the cylinder selection means determines that the cylinder with the larger integrated value has the higher cylinder priority, and selects the cylinder to be preferentially cylinder-stopped. It is characterized in that a cylinder having a smaller integrated value is determined to have a higher cylinder priority, and is selected as a cylinder to be preferentially restored. Therefore, when the cylinder is closed, it is determined that the cylinder with the larger integrated value among the operating cylinders in operation has the higher cylinder priority, and the cylinder is preferentially closed, and when the cylinder is returned, the integrated value among the cylinders in the closed cylinder is smaller. It is determined that the higher the cylinder, the higher the cylinder priority, and the cylinder is preferentially returned.

As a result, the degree of deterioration of each cylinder is leveled extremely satisfactorily, the frequency of maintenance can be minimized, and the maintenance interval can be extended to the maximum, and the running cost can be extremely suppressed. Can be

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration diagram in a case where an internal combustion engine with a cylinder deactivation function according to the present invention is applied as a stationary internal combustion engine used in an air conditioner. The configuration of an internal combustion engine with a cylinder deactivation function according to the present invention will be described.

The engine body of the internal combustion engine with the cylinder deactivation function, that is, the engine 1 is, as shown in a longitudinal sectional view in FIG. 1, a spark-ignition type four-cycle, two-valve, four-cylinder engine. # 1 cylinder, # 2 cylinder, # 3 cylinder, # 4
They are arranged in series like cylinders. Describing a cylinder # 1 as a representative, a piston 4 is slidably fitted along a liner (inner wall) in a cylinder 3 of each cylinder formed in the cylinder block 2, and the piston 4 is connected. It is connected to a crankpin 8 a of a crankshaft 8 via a rod 6. That is, when the piston 4 slides in the cylinder 3, the crankshaft 8 supported by the cylinder block 2 rotates accordingly.

On the other hand, the cylinder head 10 is provided with an intake port 12 and an exhaust port 14 and the cylinder 3 and the piston 4
The intake port 12 is connected to an intake pipe 13, and the exhaust port 14 is connected to an exhaust pipe 15. Intake port 1
2 is provided with an intake valve 18 for performing communication and shutoff between the intake port 12 and the combustion chamber 16.
An exhaust valve 20 is provided to perform communication and cutoff between the exhaust port 14 and the combustion chamber 16. Incidentally, the intake valve 18 and the exhaust valve 20 are normally connected to the valve spring 2 which is contracted between the cylinder head 10 and the valve spring retainer 21.
2 to shut off both ports.

The cams 28 of the camshaft 26 which is supported by the second cylinder head 11 on the cylinder head 10 via the valve lifters 24 with built-in suspension devices respectively contact the heads of the valve stems of the intake valve 18 and the exhaust valve 20. Usually, when the crankshaft 8 rotates, the crank pulley 30, the belt 32, the camshaft pulley 3
4, the camshaft 26 rotates, and the intake valve 18 and the exhaust valve 20 are opened and closed via a valve lifter 24 with a built-in suspension device in response to the movement of a cam 28 that rotates together with the camshaft 26. The opening and closing operation of the intake valve 18 and the exhaust valve 20 is a general operation, and a detailed description thereof will be omitted.

Referring to FIG. 2, there is shown a detailed view of the valve lifter 24 with a built-in suspension device. Hereinafter, the configuration of the valve lifter 24 with a built-in suspension device will be described with reference to FIG. A node 41 is formed substantially at the center of the cylindrical lifter body 40 of the valve lifter 24 with a built-in suspension device.
A cylinder 42 having an axis extending in the same direction as the axis of the lifter main body 40 is drilled at a substantially central portion of the cylinder 42. A sliding rod 44 slidable in the cylinder 42 is fitted in the cylinder 42.

As shown in FIG. 1, the sliding rod 44 is positioned such that the tip thereof is in contact with the head of the valve stem of the intake valve 18 or the exhaust valve 20. A circumferential groove for locking 44a is formed. A cam 28 is provided on the upper edge of the lifter body 40.
And a pad 46 that is in contact with the
A spring 48 is provided between the
Has been curtailed. That is, the sliding rod 44
Is biased by a spring 48 so that the flange 45 and the upper end of the cylinder 42 come into contact with each other. In the figure,
Reference numeral 47 denotes a guide for a spring 48 and reference numeral 49 denotes a guide.
Is a sheet member that is provided in contact with the pad 46 and pressed against the lifter main body 40 and supports the guide 47 and the spring 48.

An oil passage 50 is formed in the node 41 so as to be orthogonal to the axis of the lifter main body 40. The oil passage 50 has a circumferential groove 52 formed in the cylinder 42. Also, it communicates with a cylinder 54 that is also formed so as to be orthogonal to the axis of the lifter main body 40. The cylinder 54 is provided with a lock piston 5 slidable in the cylinder 54.
6 is fitted, and a lock portion 62 of the lock piston 56 protrudes from the tip of the lock piston 56.
Further, a spring 60 is contracted between the lock piston 56 and a spring seat 58 for closing the cylinder 54, whereby the flange 45 and the cylinder 42 are closed.
The lock portion 62 is engaged with, ie, locked with, the locking circumferential groove 44 a of the sliding rod 44 in a state where the upper end of the sliding rod 44 is in contact with the upper end of the sliding rod 44. That is, the lock portion 62
Is locked in the locking circumferential groove 44a,
The lifter body 40 and the sliding rod 44 are integrated.

Then, the valve lifter 2 with a built-in suspension device is provided.
4, the locking portion 62 is thus locked with the locking circumferential groove 44.
a and a slight clearance between the sliding rod 44 and the heads of the valve stems of the intake valve 18 and the exhaust valve 20 with the cam 28 not pressing the pad 46 as shown in FIG. Is caused to occur. In other words, the valve lifter 24 with a built-in rest device has a predetermined tappet clearance when the lock portion 62 is locked in the lock circumferential groove 44a.

A spring 64 is contracted between the joint 41 and the cylinder head 10. The spring 64 constantly presses the lifter main body 40 and the pad 46 against the cam 28 to reduce a so-called tappet sound. It is possible to do. Reference numerals 66 and 68 are both sheet members. The second cylinder head 11 has
A guide portion 70 for slidably holding the lifter main body 40 is provided, and an oil passage 72 is formed on the inner periphery of the guide portion 70. The second cylinder head 11 is the cylinder head 1
0, and the lifter body 40 is
Is pressed, the lifter main body 40 is guided by the guide portion 70 and reciprocates.

As shown in the figure, an oil passage 72 on the inner periphery of the guide 70 communicates with the oil passage 50 in the node 41.
The oil passage 72 is formed to have a predetermined width in the sliding direction, so that the oil passage 72 and the oil passage 50 always communicate even if the lifter body 40 reciprocates with respect to the guide portion 70. Maintained in state. An oil passage 80 extends from the guide portion 70, and a hydraulic supply source and an oil reservoir are connected to the oil passage 80 via an electromagnetic three-way valve 82. actually,
Here, since engine oil is shared as hydraulic oil, the oil pressure supply source is an engine oil circulation mechanism provided in the engine 1, and the oil reservoir is an oil pan (reference numeral 8 in FIG. 3).
3). The electromagnetic three-way valve 82 is provided for each of the valve lifters 24 with a built-in rest device, and is attached to the cylinder head cover 10a as shown in FIG.

Referring to FIG. 3, an engine oil circulation mechanism is shown. As shown in the figure, in the engine oil circulation mechanism, when the low-pressure pump (OP1) 84 is operated by the driving force of the engine 1, the engine oil in the oil pan 83 is passed through an oil filter 85 to an oil passage 86.
And distributed from the oil passage 86 to the cam journals (J1 to J4) 87, the crank journals (J1 to J4) 88, the crankpins (P1 to P4) 89, and the like via the respective galleries. I have. further,
In the engine oil circulation mechanism, a high-pressure pump (OP2) 93 driven by the driving force of the engine 1 through an oil passage 86
The engine oil that has been pressurized by the high-pressure pump 93, that is, the operating oil, is supplied to the electromagnetic three-way valve 8.
2 and the intake valve 18 side (IN1, IN2, IN3, IN
4) and the exhaust valve 20 side (EX1, EX2, EX)
3 and EX4) are supplied to the valve lifters 24 with built-in rest devices.

The three-way valve 82 is higher than the high-pressure pump 93.
An accumulator (ACC) 95 is interposed in the oil passage 86 on the side together with the one-way valve 94, so that even when the engine 1 rotates at a low speed and the discharge pressure of the high-pressure pump 93 decreases, the suspension device is built in. A sufficient hydraulic pressure (line pressure) is supplied to the valve lifter 24 so that the lock piston 56 can be operated. Also, in the figure, reference numeral 96,
Reference numeral 97 denotes a regulator valve provided in parallel with the low-pressure pump 84 and the high-pressure pump 93.

The operation of the thus-configured valve lifter 24 with a built-in rest device will be briefly described. Normally, the valve lifter 24 with a built-in suspension device is in the state shown in FIG. 2, and the three-way valve 82 is at a switching position for communicating the oil passage 80 with the oil pan 83. That is, normally, the hydraulic oil in the oil passage 80 is discharged to the oil pan 83, and the oil pressure in the oil passage 80, the oil passage 50, and the circumferential groove 52 is released.

Therefore, at normal times, the lock piston 56
Is urged by the spring 60, and the lock portion 62 is locked in the lock circumferential groove 44a. When the cam 28 presses the pad 46 in this state, as shown in FIG. The sliding rod 44 reciprocates integrally with the lifter main body 40, and the intake valve 18 and the exhaust valve 20 open and close.

On the other hand, when the three-way valve 82 is switched to the switching position where the oil passage 80 and the hydraulic supply source communicate with each other, the hydraulic oil from the hydraulic supply source passes through the oil passage 80 and the oil passage 50 in a circle. Supplied to the circumferential groove 52, the lock piston 56 is pushed back against the spring 60, so that the lock portion 62 is disengaged from the lock circumferential groove 44a. in this way,
When hydraulic oil is supplied from a hydraulic supply source and the lock between the lock portion 62 and the lock circumferential groove 44a is released, the spring 48 is sufficiently weaker than the urging force of the valve spring 22. Presses the pad 46, as shown in FIG.
4 is a spring 4 regardless of the reciprocation of the lifter body 40.
8 slides in the cylinder 42 while expanding and contracting, and the intake valve 1
8 and the exhaust valve 20 are held in the same position without opening and closing. That is, in this case, the cam 28 is
Even if 6 is pressed, the intake valve 18 and the exhaust valve 20 are kept open without being opened at all.

Referring again to FIG. 1, the intake pipe 13 includes:
An electromagnetic throttle valve 100 driven by a step motor 144 is provided, and a fuel pipe 10 for fuel supply is provided upstream of the throttle valve 100.
2 are connected. That is, the throttle valve 100
Is adjusted, the amount of air is adjusted, and fuel is supplied from the fuel pipe 102 into the intake pipe 13 by the negative pressure generated according to the opening of the throttle valve 100. The intake pipe 13 is also provided with an air cleaner 13a.

In the present embodiment, a fuel gas (city gas, propane gas, etc.) that can be continuously supplied for a long period of time is used as fuel for the engine 1, thereby making it easy to use and relatively clean of fuel-efficient exhaust gas. A simple internal combustion engine has been realized. A fuel control linear valve 104 for adjusting the supply amount of the fuel gas is interposed in the fuel pipe 102, and a fuel passage is opened and closed upstream of the fuel control linear valve 104 in accordance with the operation / stop of the engine 1. A fuel gas solenoid valve 106 is provided.

A spark plug 90 is provided on the cylinder head 10 at a position substantially at the center of the cylinder 3 of each cylinder. The spark generating portion of the spark plug 90 has an electrode protruding toward the combustion chamber 16. ing. And the spark plug 9
0 is connected to an ignition coil 92, and the ignition coil 92 is attached to the cylinder head cover 10a.

The crankshaft 8 has a pair of large gears 1.
A starter motor 114 is connected via a small gear 10 and a jump-type small gear 112.
The rear end is connected to an input shaft 124 of a compressor 122 provided in the heat exchange unit 120 via a clutch 126 that is disengaged when the engine 1 is started.

The heat exchange unit 120 is connected to an indoor unit 130 provided in the room via a liquid pipe 132 and a gas pipe 134 for circulating a refrigerant liquid. still,
The heat exchange unit 120 and the indoor unit 130 themselves are common and well-known in an air conditioner, and a detailed description thereof will be omitted. As shown in the figure, an intake pipe 13 is provided with an intake pressure sensor 140 capable of detecting an intake system pressure and a pulsation waveform, and an exhaust pipe 15 is provided with an exhaust pressure sensor 142 capable of detecting an exhaust system pressure and a pulsation waveform. Is provided. Further, in the vicinity of the large gear 110, the crank angle θ
A crank angle sensor 146 for detecting cr and the engine speed Ne is provided. The throttle opening can be detected from the number of steps of the step motor 144 for driving the throttle valve 100. And
The indoor unit 130 is provided with a room temperature sensor 148 for detecting the temperature in the room.

Electronic control unit (ECU) 15
Reference numeral 0 denotes a control device that controls the entire air conditioner, and the ECU 150 controls the operation of the heat exchange unit 120 and the engine 1. In FIG. 1, the engine 1
The control related to the above is mainly extracted and described. ECU
On the input side of 150, various sensors (not shown) of the heat exchange unit 120, the intake pressure sensor 140, the exhaust pressure sensor 142, the crank angle sensor 146, the room temperature sensor 14
8 etc. are connected. Further, an operation control switch 152 of the air conditioner including an operation mode selector and the like is also connected to the input side.

On the other hand, on the output side of the ECU 150, the electromagnetic three-way valve 82, the ignition coil 92, the step motor 144 for driving the throttle valve 100, the fuel control linear valve 104, the fuel gas electromagnetic valve 106, the starter motor 114, Various control valves (not shown) of the heat exchange unit 120 and the indoor unit 130 are connected.

Referring to FIG. 5, there is shown a block diagram showing the input / output relationship of signals around ECU 150 in the control of the number of operating cylinders according to the present invention. Referring also to FIG.
The operating cylinder number control function of the operating cylinder number control unit 151 in the CU 150 is also shown in a block diagram. As shown in the figure, in the internal combustion engine with the cylinder deactivation function of the present invention, as the operating cylinder number control function, It is characteristically provided with a cylinder-by-cylinder maintenance factor management means 160, an operation state management means 162, an operation cylinder number determination means 164, and an operation cylinder number change instruction means 166.

The operation of the internal combustion engine with the cylinder deactivation function configured as described above according to the present invention, that is, the control of the number of operating cylinders will be described below. Referring to FIGS. 7 to 13, a control routine for controlling the number of operating cylinders according to the present invention is shown in a flowchart. Hereinafter, referring to the block diagrams of FIGS. 5 and 6, the flowcharts of FIGS. The control of the number of operating cylinders according to the present invention will now be described.

First, in step S10 of FIG. 7, it is determined whether an engine start request has been issued. That is, the operation switch 152 is operated, or the thermostat function in the ECU 150 is activated based on the information from the room temperature sensor 148, and it is determined whether or not the start signal is input as the air conditioner operation information. If the determination result is false (No),
The execution of step S10 is repeated.

On the other hand, if the determination result is true (Yes) and there is an engine start request, the engine 1 is started. More specifically, the electromagnetic three-way valves 82 are connected to all cylinders in FIG.
(A), the fuel control linear valve 104 is set to an appropriate opening according to the type of fuel gas, the electromagnetic throttle valve 100 is opened, and the fuel gas electromagnetic valve 1 is opened.
The valve 06 is opened, the starter motor 114 is operated, and the ignition is performed by the spark plug 90. That is, at the time of starting, operation in all cylinders, that is, all cylinder operation is performed. Then, the process proceeds to step S12.

In step S12, it is determined whether or not the engine has been started, that is, whether or not the engine 1 has been operated reliably. The completion of the engine start is determined, for example, by the engine speed Ne.
Is determined based on whether or not reaches a predetermined number of revolutions. If the determination result is false (No) and the engine has not been started,
Returning to step S10, on the other hand, the determination result is true (Yes)
In the case of, the process proceeds to step S14.

In step S14, it is determined whether or not a stop request has been issued, that is, the operation switch 152 has been operated, or the thermostat function in the ECU 150 has been activated based on information from the room temperature sensor 148. It is determined whether or not is input. If the determination result is false (No), and there is no stop request, for example, immediately after the start, the process proceeds to step S16.

In step S16, the cylinder maintenance factor management means 160 measures, accumulates, and stores the maintenance factor for each cylinder (accumulation means, storage means). Here, the cylinder-by-cylinder maintenance factor is the operating time for each cylinder when spark ignition is performed by the spark plug 90 and the combustion operation is performed, or
It refers to the number of spark ignitions for each cylinder. That is, when performing cylinder closing, spark ignition and fuel supply are suspended, but the cylinder-by-cylinder maintenance factor refers to an integrated value of the operating time or the number of spark ignitions of the operating cylinder that has not been closed. .

That is, in this case, each cylinder (# 1 cylinder, # 1 cylinder)
The operation time or the number of spark ignitions is measured, integrated, and stored for each of the two cylinders, the # 3 cylinder, and the # 4 cylinder. The operation time is measured by, for example, a microcomputer provided in the ECU 150. The cylinder-by-cylinder maintenance factor is used as a discriminating value for determining a cylinder priority order and a cylinder priority order (return cylinder priority order) described later.

Since the operation involving combustion is performed in all cylinders at the time of starting, the maintenance factor is integrated in all cylinders immediately after the start of the engine. The cylinder-by-cylinder maintenance factor management means 160 also measures, accumulates, and stores the idle maintenance factor for each idle cylinder. In other words, when the cylinders are closed, the suspension maintenance factor, that is, the suspension time, is measured, integrated, and stored for each cylinder that has been closed, in addition to the cylinder-by-cylinder maintenance factor. The operation time is measured, for example, by the ECU 150 as described above.
The time is measured by a microcomputer provided in the inside.

This pause maintenance factor is used as a determination value for performing a preventive cylinder described later. In step S18, the operating state management means 162 monitors and stores the load state of the engine 1, and further monitors and stores the number of operating cylinders. Specifically, a step motor drive signal, that is, information on a throttle opening degree step nth is stored, and the cylinder and the number of cylinders that are currently performing a combustion operation are stored.

In step S20, the operating cylinder number determining means 1
At 64, the load change is calculated to determine the number of operating cylinders (operating cylinder number setting means). That is, a throttle opening step change rate Δnth, which is a time change of the throttle opening step nth, is calculated based on the throttle opening step nth information which is a step motor drive signal, and the throttle opening step nth and the throttle opening step change are calculated. The number of operating cylinders is determined according to the calculated value of the speed Δnth. Specifically, the number of operating cylinders is determined based on the maps of FIGS.

FIG. 14 shows a map of the required number of operating cylinders according to the engine speed Ne and the output torque. In FIG. 14, the solid line indicates the switching torque to the increased cylinder side, and the broken line indicates the reduced cylinder side. 5 shows the switching torque to. In general, as the output torque is larger and the engine speed Ne is smaller and the number of cylinders is smaller, the engine 1 vibrates and causes noise and the like. Here, the vibration limit is set for each cylinder. In the operating cylinder number map, the vibration limit of each cylinder is also indicated by a solid line.

Further, referring to FIG. 15, there is shown a cylinder number switching map which is set in advance in consideration of the balance between the exhaust gas and the output according to the engine speed Ne and the throttle opening step nth at each cylinder number. ing. 14, a solid line indicates a throttle opening degree step nth corresponding to the increased cylinder side torque (solid line) in FIG. 14, and a broken line indicates a throttle opening degree step n corresponding to the reduced cylinder side torque (dashed line) in FIG.
indicates th. That is, the throttle opening step nth
When the throttle opening degree step nth increases based on the cylinder number switching map and exceeds the solid line, the number of cylinders increases by one cylinder, while the throttle opening degree step nth
Is decreased below the broken line, the number of cylinders is switched so as to decrease by one cylinder.

In the meantime, as schematically shown by radial arrows in FIG.
The time required for the throttle opening step nth to reach the solid line or the broken line differs depending on the change speed of th. That is,
When the throttle opening step change speed Δnth is large, the speed immediately reaches the solid line or the broken line.
However, on the other hand, when the number of operating cylinders is reduced, that is, the cylinders are stopped, or increased, that is, the number of operating cylinders is increased (return cylinder), in this embodiment, in addition to performing the stop and restart of the spark ignition, As will be described later, locking of the valve lifter 24 with built-in suspension device is performed to stop and restart the operation of the intake valve 18 and the exhaust valve 20 for the purpose of suppressing the fuel efficiency reduction of the engine 1 and stopping and restarting the fuel supply. Since the piston 56 is operated, a response delay for switching occurs in the throttle valve 100 and the valve lifter 24 with a built-in suspension device. This means that proper control cannot be performed if cylinder closing or cylinder increase is started after the throttle opening degree step nth reaches the solid line or the broken line.

Therefore, when the throttle opening step change speed .DELTA.nth is large, control is performed such that the start of cylinder closing and cylinder increase is accelerated in accordance with the throttle opening step change speed .DELTA.nth. In this way, when the throttle opening step nth reaches the solid line or the broken line, a stable cylinder stop or cylinder increase is always realized. As a result, it is possible to suitably avoid a reduction in fuel efficiency due to an engine stop due to a delay in increasing cylinders or a prematurely reduced cylinder, or a delay in increasing or prematurely decreasing a cylinder.

In this case, it is effective to monitor the throttle opening step nth and the throttle opening step change speed Δnth, and determine the switching timing using, for example, fuzzy calculation. Although the throttle opening step nth information, which is a step motor drive signal, is used here, a boost pressure sensor is provided, and the number of cylinders is switched based on the boost pressure information from the boost pressure sensor. Is also good. In this case, boost pressure change speed information may be used for the throttle opening step change speed Δnth.

Since the relationship between the throttle opening step nth and the engine speed Ne actually changes due to individual variations, aging deterioration, atmospheric pressure fluctuations, etc., the cylinder number switching map is learned and corrected according to these. To More specifically, the throttle opening degree step nth is controlled based on the required rotation speed of the engine 1, and correction is performed by checking the difference between the required engine rotation speed and the current actual engine rotation speed Ne.

Since the relationship between the throttle opening step nth and the engine speed Ne differs depending on the type of fuel gas, the cylinder number switching map is corrected in advance in accordance with the type of fuel gas. In step S22, in order to perform a preventive cylinder, the deactivated maintenance factor integrated value obtained as described above is compared with a predetermined reference value, and among deactivated cylinders, deactivated cylinders that exceed the predetermined reference value, The right to restart the operation, that is, the right to perform the preventive cylinder change, is generated.

The preventive cylinder means an operation of forcibly resuming a cylinder which has been stopped by a cylinder deactivation, that is, an operation of returning the cylinder. In the engine 1, even when the cylinder is closed and spark ignition and fuel supply are stopped, engine oil is always supplied to the sliding surface between the cylinder 3 and the piston 4, and the engine oil adheres to and remains in the combustion chamber 16. The spark plug 90 may become dirty, and in some cases, the intake valve 18 and the exhaust valve 20 may form a so-called valve stick. Therefore, in this case, if the cylinder rest state continues for a certain period of time, the cylinder is forcibly returned in order to burn and remove deposits such as engine oil.

In step S24, it is determined whether or not the change is prohibited. In other words, based on the execution results of steps S16 to S22, the cylinders to be closed, increased, or prevented are changed, but are the restriction conditions for changing the number of cylinders not satisfied? It is determined whether or not. More specifically, the engine speed Ne such as at the time of engine start, idling, low-speed high-load operation, etc.
Is lower than the vibration limit shown in FIGS. 14 and 15, the restriction condition is satisfied, and the change is prohibited.

The determination result of step S24 is true (Yes).
If the change prohibition is satisfied, the process returns to step S12 without changing the number of operating cylinders. On the other hand, when the determination result is false (No) and does not correspond to the change prohibition, the process proceeds to step S26. In step S26, it is determined whether or not to change the number of cylinders or preventive cylinders. That is, it is determined whether or not to change the number of cylinders based on the execution result of step S20, that is, the cylinder number switching map in FIG. 15, and whether or not to forcibly return the cylinder based on the execution result of step S22. . If the determination result is false (No), it is not necessary to change the number of cylinders, and if the integrated value of the suspension maintenance factor has not reached the predetermined reference value and there is no need to perform preventive cylinder shifting, the step Returning to S14, the execution of steps S16 to S22 is repeated. On the other hand, if the determination result is true (Ye
If it is determined in s) that it is necessary to change the number of cylinders or preventive cylinders, the process proceeds to step S28.

In step S28, control that leads to a sudden change in load is prohibited. In other words, when the number of cylinders is changed from now on, the operation mode is set so that the number of operating cylinders does not further change during the cylinder change even if the operation mode selector of the operation switch 152 is operated. And the change control is temporarily suspended, so that the load applied to the engine 1 during the change, that is, the output torque required of the engine 1 does not suddenly change.

In step S30, it is determined whether the requested change in the number of cylinders is a closed cylinder, an increased cylinder (return cylinder), or a preventive cylinder. If the result of determination is that the change in the number of cylinders is a closed cylinder, the process proceeds to step S32. In step S32, the cylinder to be cylinder-stopped is selected by the cylinder-to-cylinder selection function of the operating cylinder number change instructing means 166 (comparison means, cylinder-to-cylinder selection means).

More specifically, among the cylinder-by-cylinder maintenance factor integrated values accumulated and stored in step S16, the cylinder-by-cylinder maintenance factor integrated values of the currently operating operating cylinders are compared with each other, and the value of the cylinder-by-cylinder maintenance factor integrated value is compared. Are set in order from the cylinder having the largest number. In other words, when all the cylinders # 1 to # 4 are operating, for example, when the operating time of the # 1 cylinder is longest and the cylinder-by-cylinder maintenance factor integrated value is large, the # 1 cylinder is most likely to operate. The priority is set as a high priority. Then, based on the cylinder priority order, the cylinders with the highest cylinder priority order are selected as the cylinders to be suspended in order.

At this time, cylinder closing is selected in consideration of priority restrictions. This priority restriction is mainly performed in order to prevent deterioration of engine vibration. Considering that the combustion order of the engine 1 is in the order of # 1 cylinder- # 3 cylinder- # 4 cylinder- # 2 cylinder. Here, the priority restrictions are as follows (1) to (3). (1) In the case of 1-cylinder idle cylinder: No limit (2) In the case of 2-cylinder idle cylinder: (# 1 cylinder and # 4 cylinder),
Among the combinations of (# 2 cylinder and # 3 cylinder), the combination having the largest integrated value of the maintenance factor for each cylinder is closed. (3) In the case of 3-cylinder closed cylinder: In addition to the selection of the above-described two cylinders,
Cylinders with a large cylinder-to-cylinder maintenance factor integrated value of the remaining cylinders are deactivated. Immediately after starting the engine 1 for the first time, there is no difference in the cylinder-by-cylinder maintenance factor integrated value. I will keep it.

As described above, if the cylinders with the largest cylinder-to-cylinder maintenance factor values are preferentially closed based on the cylinder number switching map shown in FIG. 15, the number of cylinders to be closed can be increased as much as possible without restriction. By preventing the cylinders to be cylinder-stopped from being always the same, it is possible to eliminate the bias of deterioration in all the cylinders, level the degree of deterioration, and prolong the life of the engine 1 as a whole. In other words, it is possible to improve the fuel efficiency and to suppress the deterioration of the engine 1, and it is possible to extend the maintenance interval by minimizing the frequency of maintenance as much as possible. As a result, it is possible to suppress the running cost as a whole. You can do it.

Specifically, in addition to improving fuel efficiency by using a large number of closed cylinders, by eliminating the bias of the cylinders to be closed,
With respect to the spark plug 90, deterioration can be delayed by reducing the number of ignitions and eliminating the bias as compared with the case without the cylinder deactivated, and deterioration of the engine oil due to blow-by gas is reduced by reducing the amount of blow-by gas. , The life of the oil filter 85 and the oil separator (not shown) can be extended,
Furthermore, the life of the air filter 13a can be extended by reducing the amount of intake air. In addition, the opportunity to stop the operation of the intake valve 18 and the exhaust valve 20 for all cylinders increases, so that the tip of the sliding rod 44 and the intake valve 1
8. The wear of the exhaust valve 20 or the peripheral members can be reduced, and the tappet clearance and the like can be favorably maintained for a long period of time without frequent adjustments and component replacements.

After selecting the cylinders as described above,
In the next step S34, a cylinder closing command is issued, and in step S36, a cylinder number changing operation for cylinder closing is performed (control means). Specifically, in the cylinder number changing operation for the cylinder to be closed, the subroutine of FIG. 12 is executed. In step S60 of FIG. 12, first, the engine speed Ne is adjusted to the cylinder-stop operation speed. That is, as described later, when the cylinder is closed, the three-way valve 82 is switched to the position shown in FIG.
The lock portion 62 is released by pressing the lock piston 56 of the valve lifter 24 with the suspension device with hydraulic oil so as not to open the intake valve 18 and the exhaust valve 20. This unlocking operation can be completed within one cycle. , The engine rotation speed Ne is kept at a relatively low cylinder deactivation operation rotation.

In step S62, the ignition timing is adjusted to the retard side, and the throttle opening step nth is adjusted to the opening after cylinder closing. That is, when the cylinder is closed, the throttle opening step nth is controlled to increase to secure the engine speed Ne. At this time, the ignition timing is set to the retard side in consideration of the response delay of the throttle valve 100. , The throttle opening step nth, that is, the opening of the throttle valve 100 is previously adjusted to the predicted opening after the cylinder closing is completed.

In step S64, the opening and closing of the intake valve 18 of the cylinder to be stopped is stopped. That is, in the present embodiment, when the cylinder is closed, the spark ignition is stopped,
The intake valve 18 and the exhaust valve 20 are closed to suppress the pumping loss and cut off the fuel supply. Here, the opening and closing of the intake valve 18 is first stopped. Specifically, as described above, the three-way valve 82 is switched to the position shown in FIG.
6 is pressed with hydraulic oil to release the engagement of the lock portion 62, and the sliding rod 44 does not push the intake valve 18.

When the opening and closing of the intake valve 18 is stopped as described above, the fuel gas is not supplied into the combustion chamber 16 at the same time, and the fuel supply is stopped at the same time. In step S66, it is confirmed whether or not the intake valve 18 whose opening and closing has been stopped in this way has actually stopped reliably. Specifically, based on the information from the intake pressure sensor 140, the pressure pulsation in the intake pipe 13 and the like are monitored.

Then, in step S68, it is determined whether or not the intake valve 18 has stopped reliably. If the determination result is false (No), the process proceeds to step S69, where the intake valve 18 in step S64 is determined. It is determined whether or not the opening / closing stop operation has exceeded a predetermined number of trials. If the result of the determination in step S69 is false (No) and the number of trials has not yet exceeded the limit, the process returns to step S64 to continue the opening / closing stop operation of the intake valve 18. On the other hand, step S69
If the determination result is true (Yes) and it is determined that the number of tries has been exceeded, the routine exits from the routine.

The determination result of step S68 is true (Yes)
If it is determined that the intake valve 18 has stopped without fail, the process proceeds to step S70. In step S70,
The operation of the ignition coil 92 of the cylinder to be closed is stopped, and the spark ignition is stopped. Then, in step S72, the opening and closing of the exhaust valve 20 of the cylinder to be stopped is stopped. The opening / closing stop of the exhaust valve 20 is performed by switching the three-way valve 82 to the position shown in FIG. That is, the sliding rod 44 of the valve lifter 24 with the suspension device is prevented from pushing the exhaust valve 20.

In step S74, it is checked whether the exhaust valve 20 whose opening and closing has been stopped in this way has actually stopped reliably. Specifically, based on information from the exhaust pressure sensor 142, the pressure pulsation in the exhaust pipe 15 is monitored and the like.
Then, in step S76, it is determined whether or not the exhaust valve 20 has stopped reliably. If the determination result is false (No), the process proceeds to step S77, and the process proceeds to step S72.
It is determined whether or not the opening / closing stop operation of the exhaust valve 20 has exceeded the predetermined number of trials.

If the result of the determination in step S77 is false (No) and the number of tries has not yet exceeded the limit, the procedure returns to step S72 to continue the opening / closing stop operation of the exhaust valve 20. On the other hand, if the result of the determination in step S77 is true (Yes) and it is determined that the number of tries has been exceeded, the routine exits from the routine. If the decision result in the step S76 is true (Y
If it is determined in es) that the exhaust valve 20 has stopped without fail, the process proceeds to step S78.

In step S78, since the operation for closing the cylinder has been completed as described above, step S62 is performed.
The ignition timing, which has been retarded in the above, is returned to the normal state.
At this time, the throttle opening step nth is the throttle opening step nth after the cylinder is closed by the retard control in step S62. Then, in step S79, in response to the end of the operation for cylinder deactivation, a cylinder deactivation completion declaration is transmitted, and the operation for changing the number of cylinders for cylinder deactivation is terminated.

When the opening and closing of both the intake valve 18 and the exhaust valve 20 are stopped as described above, the air in the combustion chamber 16 is compressed by the piston 4, and this compression work is thereafter performed by the compression work. Since the work is expanded by performing the expansion work on the piston 4, the energy is not lost. Also, here, first, the intake valve 18
After stopping the opening of the exhaust valve 20, the opening of the exhaust valve 20 is stopped. This is because if the exhaust valve 20 is closed first and spark ignition is performed, then the intake valve 18 is opened. This is because the combustion gas may flow back to the intake system to generate a so-called backfire, or the in-cylinder pressure may rise abnormally, causing the engine 1 to stop or be damaged. This is because the intake air may flow backward to affect the flow of intake air to other cylinders or the air-fuel ratio.

When the operation for changing the number of cylinders for the closed cylinder is completed,
Proceeding to step S38 in FIG. 8, it is determined whether the change has been completed. That is, it is determined whether or not the cylinder number changing operation for cylinder closing shown in FIG. If the result of the determination is false (No) and the cylinder number change operation for closing the cylinder has not been completed by transmitting the cylinder closing completion declaration, that is, if the operation has exceeded the limit number of tries, then the process proceeds to step S40. Proceed to.

In step S40, it is further determined whether or not the number-of-cylinder changing operation for the closed cylinder has exceeded a predetermined number of change try limits. If the determination result is false (No) and the cylinder number change operation does not exceed the change try limit number,
Returning to step S36, the operation of changing the number of cylinders for closing cylinders is continued. On the other hand, if the determination result is true (Yes) and it is determined that the number-of-cylinder change operation has exceeded the change try limit number,
Proceed to step S42.

In step S42, a malfunctioning portion is displayed on a display device (not shown) and an abnormality is declared, the operation for changing the number of cylinders is stopped, and an all-cylinder operation command is issued. In other words, if the change is not completed even if the change try limit is exceeded, there is some abnormality, and it is preferable that the cylinders are no longer closed. In this case, the operation is performed with all cylinders.

In step S44, as in the case of the cylinder number changing operation, it is determined whether or not the operation for all cylinder operation has exceeded the all cylinder try limit number. If the determination result is false (No),
If the operation for all-cylinder operation is completed within the all-cylinder try limit number, the process proceeds to step S46, in which an all-cylinder operation declaration due to an abnormality is made, and the process returns to step S14 in FIG. On the other hand, if the determination result is true (Yes) and the operation for all-cylinder operation exceeds the all-cylinder try limit number, it can be determined that there is an abnormality in the engine 1, and in this case, step S4
In step 8, the abnormality declaration made in step S42 is updated as it is, and the process returns to step S14. In addition, even if such an abnormal declaration is made, the control of the number of operating cylinders is continued,
In this case, it is necessary to repair the abnormal part immediately based on the display of the malfunctioning part of the display device.

On the other hand, if the decision result in the step S38 is true (Y
es), if it is determined that the change has been completed successfully,
In step S50, the completion of the change in the number of cylinders is declared, and the process returns to step S14. As a result of the determination in step S30,
If the change in the number of cylinders is to increase the number of cylinders (return cylinder), the process proceeds to step S80 in FIG.

In step S80, the cylinder to be increased (returned cylinder) is selected by the increased cylinder selection function (return cylinder selection means) of the operating cylinder number change instructing means 166 (comparing means, return cylinder selection means). Specifically, among the cylinder-by-cylinder maintenance factor integrated values accumulated and stored in step S16, the cylinder-by-cylinder maintenance factor integrated values of the cylinders that are currently closed are compared with each other, and the cylinder-by-cylinder maintenance factor integrated value is the smallest. , The priority order of additional cylinders is set in order. That is, in a case where three cylinders # 1 to # 3 are in a closed state, for example, when the operation time of the # 1 cylinder is short and the maintenance factor integrated value per cylinder is small, the # 1 cylinder is the most The priority is set as a high priority. Then, based on the cylinder addition priority, the cylinders with the higher cylinder priority are selected as cylinders to be added in order.

At this time, as in the case of the above-mentioned closed cylinder, the additional cylinder is selected in consideration of the priority restriction. For the same reason as described above, the priority restrictions are as follows (1) to (3). (1) In the case of cylinder extension from cylinder 1 to cylinder stop: no restriction (2) In the case of cylinder extension from cylinder 2 to cylinder extension: no restriction (3) In the case of cylinder extension from cylinder 3 to cylinder extension: (# 1 cylinder and # 4)
Among the combinations of (cylinders) and (# 2 cylinders and # 3 cylinders), the cylinders with the smallest cylinder-by-cylinder maintenance factor integrated value are added to the cylinders. If you try to
As in the case of the above-mentioned cylinders, the degree of deterioration can be equalized for all cylinders without the bias of deterioration, and the maintenance interval can be extended by minimizing the frequency of maintenance. Thus, the running cost can be reduced as a whole.

When the cylinder to be increased is selected as described above, a cylinder increase command is issued in the next step S82, and a cylinder number changing operation for increasing the cylinder is performed in step S84 (control means). Specifically, in the cylinder number changing operation for increasing the number of cylinders, a subroutine in FIG. 13 is executed. In step S100 of FIG. 13, first, the engine speed Ne is adjusted to the cylinder increasing operation speed. The change to the cylinder increasing operation speed is performed based on the same reason as in the case of the cylinder deactivation operation, and is as low as the cylinder deactivation operation speed.

In step S102, the ignition timing is adjusted to the advanced side, and the throttle opening step nth is adjusted to the opening after the increased cylinder. In other words, when adding cylinders,
The throttle opening step nth is controlled to decrease because the engine speed Ne suddenly increases. At this time, the throttle opening step nth is increased after the cylinder is increased in consideration of the response delay of the throttle valve 100. The ignition timing is controlled to the advanced side to match the degree. Due to the increase in the output of the engine 1 due to the ignition advance, the throttle valve 100 automatically operates to the valve closing side, and is adjusted to the predicted opening degree after the increase in the number of cylinders.

In step S104, the operation of the exhaust valve 20 which has stopped the cylinder to be increased is restarted. Specifically, as described above, the three-way valve 82 is returned to the normal position as shown in FIG.
Hydraulic oil that has pressed the lock piston 56 is released to engage the lock portion 62 with the lock circumferential groove 44a.

In step S106, it is confirmed whether or not the exhaust valve 20 thus operated has actually operated reliably. Specifically, based on information from the exhaust pressure sensor 142, the pressure pulsation in the exhaust pipe 15 is monitored and the like. Then, in step S108, it is determined whether or not the exhaust valve 20 has been operated reliably. If the determination result is false (No), the process proceeds to step S109, and the process proceeds to step S10.
It is determined whether or not the operation of restarting the operation of the exhaust valve 20 in Step 4 has exceeded a predetermined number of times of try.

The determination result of step S109 is false (No)
If the number of tries has not exceeded the limit number of times yet, the flow returns to step S104 to continue the operation of restarting the operation of the exhaust valve 20. On the other hand, the determination result of step S109 is true (Yes).
If it is determined that the number of tries has exceeded the limit number of times, the routine exits the routine. If the result of the determination in step S108 is true (Yes), and it is determined that the exhaust valve 20 has been reliably operated, the process proceeds to step S110.

In step S110, the operation of the ignition coil 92 of the cylinder to be increased is restarted to perform spark ignition. Then, in step S112, the operation of the intake valve 18 of the cylinder to be increased is restarted. Intake valve 1
8, the three-way valve 82 is operated as shown in FIG.
This is performed by returning to the normal position as shown in FIG. That is, the hydraulic oil that has pressed the lock piston 56 of the valve lifter 24 with the suspension device is drained, and the lock portion 62 is engaged with the lock circumferential groove 44a.

When the operation of the intake valve 18 is restarted in this way, fuel gas is simultaneously supplied into the combustion chamber 16, and fuel supply is restarted at the same time. In step S114, it is confirmed whether or not the intake valve 18 whose operation has been restarted as described above actually operates reliably. Specifically, the intake pressure sensor 140
The pressure pulsation in the intake pipe 13 and the like are monitored based on the information from.

Then, in step S116, it is determined whether or not the intake valve 18 has been operated reliably. If the determination result is false (No), the process proceeds to step S117, where the intake valve 18 in step S112 is determined. It is determined whether or not the operation restart operation has exceeded the predetermined number of times of try. If the result of the determination in step S117 is false (No) and the number of tries has not exceeded the limit number of times, the process returns to step S112, and the operation of restarting the operation of the intake valve 18 is continued. On the other hand, if the result of the determination in step S117 is true (Yes) and it is determined that the number of times of try has been exceeded, the routine exits the routine.

If the decision result in the step S116 is true (Ye
If it is determined in s) that the intake valve 18 has been reliably operated, the process proceeds to step S118. Step S118
Then, after the operation for increasing the number of cylinders is completed as described above, the ignition timing advanced in step S102 is returned to the normal state. At this time, the throttle opening step nth is the throttle opening step nth after the cylinder is increased by the advance control in step S102.

Then, in step S119, the completion of the operation for increasing the number of cylinders is transmitted in response to the completion of the operation for increasing the number of cylinders, and the operation for changing the number of cylinders for increasing the number of cylinders ends. Here, the opening of the intake valve 18 is restarted after the opening of the exhaust valve 20 is restarted. However, this is similar to the case of the cylinder closing operation, in which the intake valve 18 is opened first. When the valve spark ignition is performed, the exhaust gas 20 does not open, so that the combustion gas flows back to the intake system to generate a so-called backfire, or the in-cylinder pressure abnormally increases, and the engine 1 may be stopped or damaged. This is because, even when spark ignition is not performed, intake air may flow backward to affect the flow of intake air to another cylinder or the air-fuel ratio.

After completing the operation for changing the number of cylinders for increasing the number of cylinders,
Proceeding to step S86 in FIG. 9, it is determined whether the change has been completed. That is, it is determined whether or not the cylinder number changing operation for increasing the number of cylinders in FIG. If the determination result is false (No) and the cylinder number change operation for increasing the number of cylinders has not been completed after transmitting the cylinder addition completion declaration, that is, if the number of tries has exceeded the limit number of tries, the process proceeds to step S88. Proceed to.

Note that step S88 after step S88
Steps S98 to S98 are the same as those in the case of the cylinder rest operation described above (steps S40 to S50), and a description thereof will be omitted. If the result of determination in step S30 is that the change in the number of cylinders is a preventive cylinder, the process proceeds to step S120 in FIG.

In step S120, in the preventive cylinder function of the operating cylinder number change instructing means 166, an operation command for the relevant cylinder is issued in order to perform the preventive cylinder of the relevant cylinder. Then, in step S122, a cylinder increase operation is performed, and in step S124, a preventive cylinder operation is performed.
In step S126, the maintenance factor for each cylinder after the completion of the preventive variable cylinder is integrated, and a comparison operation between the integrated value and a specified value is performed. That is, it is monitored whether or not the preventive cylinder has been operated for a period effective enough to sufficiently prevent the trouble by sufficiently burning and removing the deposit such as the engine oil.

Then, in step S128, it is determined whether or not the cylinder-by-cylinder maintenance factor integrated value after completion of the preventive cylinder change is equal to or greater than a prescribed value. If the determination result is false (No), the flow proceeds to step S124. Return preventive cylinder operation is continued. On the other hand, if the determination result is true (Yes), the process proceeds to step S130, in which a preventive cylinder complete declaration is transmitted, and the process returns to step S14 in FIG.

As a result, deposits such as engine oil can be satisfactorily burned off and troubles can be prevented.
After the preventive cylinder change is performed, the number of operating cylinders is determined on the basis of the cylinder number switching maps shown in FIGS. 14 and 15, and the above-described control of increasing cylinders or closing cylinders is performed as usual. Further, even when the preventive cylinder is being changed, the operation of increasing the number of cylinders or closing the cylinder is performed individually based on the cylinder number switching map. Thus, it is possible to suitably prevent the engine from being stopped due to the overload of the engine 1 during the preventive cylinder change.

If the operation switch 152 is stopped or the thermostat function is activated and a stop signal is input as air conditioner operation information, the result of the determination in step S14 becomes true (Yes), and it is determined that there is a stop request. Proceeds to step S140 in FIG. As described above, when starting the engine 1, all-cylinder operation is performed. Therefore, when the engine 1 is stopped, it is necessary to return the operation state to the all-cylinder operation state in preparation for the next start.

Therefore, if there is a stop request, an all-cylinder operation command is issued in step S140 to execute all-cylinder operation. Then, in step S142, it is determined whether or not the all-cylinder operation has been completed. If the determination result is true (Yes), the engine 1 is stopped in step S148, and the process returns to step S10. On the other hand, if the determination result is false (No), the process proceeds to step S144.

In step S144, it is determined whether or not the operation for all-cylinder operation has exceeded the all-cylinder try limit number. If the determination result is false (No), the operation for all-cylinder operation is limited to the all-cylinder try limit. If the number is within the number, the process proceeds to step S148 via step S142, and after stopping the engine 1,
It returns to step S10. On the other hand, if the result of the determination in step S144 is true (Yes) and the operation for all-cylinder operation exceeds the all-cylinder try limit number, then step S146 is performed.
The engine 1 is stopped in step S148 after issuing the abnormality declaration, and the process returns to step S10. However, also in this case, it is necessary to repair the abnormal part immediately after receiving the abnormality declaration.

In the engine 1, when the oil pressure of the engine oil decreases, for example, when the engine 1 stops, the lock piston 56
Is urged to engage with the sliding rod 44. Therefore, in the engine 1, regardless of the above operation, all cylinders are automatically configured when the engine is stopped.

As described above, in the internal combustion engine with the cylinder deactivation function of the present invention, the opportunity of cylinder deactivation is increased as described above, and the concept of a maintenance factor for each cylinder is introduced to perform cylinder deactivation or cylinder expansion (return cylinder). The cylinders are effectively dispersed. Therefore, according to the internal combustion engine with the cylinder deactivation function of the present invention, it is possible to improve the fuel efficiency and suppress the deterioration of the internal combustion engine, and to maintain the maintenance by eliminating the bias of the deterioration between the cylinders and leveling the degree of the deterioration. In this case, the maintenance interval can be extended by minimizing the frequency of the operation and the running cost can be reduced as a whole.

In the above embodiment, a spark ignition type internal combustion engine using a stationary fuel gas (city gas, propane gas, or the like) used for an air conditioner as an example of the internal combustion engine with a cylinder deactivation function. However, the present invention is not limited to this, and any internal combustion engine may be used as long as it is a stationary spark ignition type internal combustion engine, and a liquid fuel such as a gasoline engine is used as a fuel. It may be something.

[0101]

As described above in detail, according to the internal combustion engine with the cylinder deactivation function of the first aspect of the present invention, the cylinder is deactivated by setting the optimum number of operating cylinders according to the load condition. By increasing the number of cylinders as much as possible, it is possible to achieve a dramatic improvement in fuel efficiency and suppression of deterioration of the internal combustion engine.Furthermore, when performing cylinder deactivation, the integrated value of the maintenance factor, that is, the number of spark ignitions and the operating time accompanying combustion , While the cylinder most effective for the cylinder at that time is selected as the cylinder to be preferentially closed,
When returning a cylinder that has been deactivated, the cylinder that is most effective for the cylinder at that time is selected as the cylinder to be returned with priority according to the integrated value of the maintenance factor. Thus, the degree of deterioration of each cylinder can be leveled, the frequency of maintenance can be minimized, the maintenance interval can be extended, and the running cost can be reduced as a whole.

According to the internal combustion engine having the cylinder deactivation function of the second aspect, when performing cylinder deactivation, it is determined that the cylinder with the larger integrated value among the operating cylinders in operation has the higher cylinder deactivation priority. When cylinders that have been deactivated are to be cylinder-reactivated, cylinders that have a smaller integrated value among cylinders that have been deactivated are determined to have a higher priority for cylinder deactivation, and cylinders that have been deactivated are given priority. Therefore, it is possible to extremely effectively prevent the bias of deterioration among cylinders, level the degree of deterioration of each cylinder, minimize the frequency of maintenance, maximize the maintenance interval, and run The cost can be extremely suitably reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram when an internal combustion engine with a cylinder deactivation function according to the present invention is applied as a stationary internal combustion engine used in an air conditioner.

FIG. 2 is a detailed view showing a valve lifter with a built-in rest device in FIG. 1;

FIG. 3 is a view showing an engine oil circulation mechanism.

FIGS. 4A and 4B are diagrams illustrating an operation state of a normal valve lifter with a built-in suspension device when the cam rotates, and an operation state of the valve lifter with a built-in suspension device when the cylinder is closed; FIGS.

FIG. 5 is a block diagram showing an input / output relationship of signals around an ECU in controlling the number of operating cylinders according to the present invention.

FIG. 6 is a block diagram showing an operating cylinder number control function according to the present invention of an operating cylinder number control unit in an ECU.

FIG. 7 is a part of a flowchart showing a control routine for controlling the number of operating cylinders according to the present invention.

FIG. 8 is the remaining part of the flowchart showing the control routine for controlling the number of operating cylinders, following the flowchart of FIG. 7;

9 is the remaining part of the flowchart showing the control routine for controlling the number of operating cylinders, following the flowchart in FIG.

FIG. 10 is the remaining part of the flowchart showing the control routine for controlling the number of operating cylinders, following the flowchart of FIG. 8;

11 is the remaining part of the flowchart showing the control routine for controlling the number of operating cylinders, following the flowchart of FIG. 7;

FIG. 12 is a flowchart showing a subroutine of a cylinder number changing operation for rest cylinder in FIG. 8;

FIG. 13 is a flowchart showing a subroutine of a cylinder number changing operation for increasing the number of cylinders in FIG. 9;

FIG. 14 is a diagram showing a map of the required number of operating cylinders according to the engine speed Ne and the output torque.

FIG. 15 is a diagram showing a cylinder number switching map according to the engine speed Ne and the throttle opening degree step nth for each number of cylinders.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine (engine main body) 3 Cylinder 18 Intake valve 20 Exhaust valve 24 Valve lifter with built-in deactivation device 90 Ignition plug 92 Ignition coil 150 Electronic control unit (ECU) 151 Operating cylinder number control unit 160 Cylinder maintenance factor management means (integration means, storage Means 162 operating state management means 164 operating cylinder number determining means (operating cylinder number setting means) 166 operating cylinder number change instructing means (comparing means, closed cylinder selecting means, return cylinder selecting means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/02 320 F02D 41/02 320 325 325C 43/00 301 43/00 301B 301H 301Z 45/00 314 45 / 00A 345A 345 345L F02P 5/15 F02P 5/15 B F term (reference) 3G022 AA04 BA01 CA01 DA01 DA02 EA07 FA08 FA09 GA01 GA02 GA05 GA07 GA08 3G084 BA05 BA13 BA17 BA23 CA01 CA03 CA04 CA07 CA09 DA14 DA19 EB02 FA00 FA02 FA10 FA11 FA33 FA35 FA36 FA38 FA39 3G092 AA01 AA14 AB07 AB08 AC07 BA09 BA10 BB01 CA04 CA05 CA07 CA08 CA09 DA01 DA02 DA06 DA11 DA14 DC03 DF04 DF09 DF10 DG05 DG08 DG09 EA04 EA09 EA11 EA12 EA13 EA12 EA13 EA13 EA12 EA13 EA12 EA12 EA12 EA12 FA50 GA01 GA03 GA14 HA05Z HA07Z HA13X HA13Z HB01X HC09X HD08Z HE01Z HE03Z 3G301 HA01 HA07 HA19 HA22 JA02 JA15 KA01 KA06 LA03 LA07 LB01 LC01 LC04 LC08 LC10 MA11 NA04 NC02 NE12 NE17 NE23 NE24 NE26 PA07Z PA12Z PB03A PD14Z PE01Z PE03Z PE10A PE10Z

Claims (2)

[Claims] At least a part of a multi-cylinder spark ignition type internal combustion engine is stopped by stopping at least fuel supply and spark ignition by a spark plug to stop combustion in the part of the cylinders and operate only with the remaining cylinders. In an internal combustion engine with a possible cylinder deactivation function, operating cylinder number setting means for setting the number of operating cylinders according to the load condition, and the number of spark ignitions or the operating time accompanying combustion in each cylinder as a maintenance factor, the maintenance factors being Accumulating means for accumulating for each cylinder, storage means for storing an integrated value by the accumulating means, comparing means for comparing the integrated values for each cylinder stored in the storing means with each other, and the operating cylinder number setting means When the number of operating cylinders is set to the decreasing side, the cylinder priority of the operating cylinder which is in operation is determined based on the comparison result of the comparing means, and the cylinder priority is determined according to the cylinder priority. Cylinder selection means for selecting a cylinder to be cylinder-stopped, and when the number of operating cylinders is set to an increasing side by the number of operating cylinders setting means, the return cylinder priority order for the cylinders in the cylinders being ceased based on the comparison result of the comparison means And a cylinder selection means for selecting a cylinder to be cylinder-returned in accordance with the cylinder return priority order; and cylinder rest information from the cylinder rest selection means and cylinder return information from the cylinder return selection means. An internal combustion engine with a cylinder stall function, comprising: a control unit that controls at least fuel supply and spark ignition of a cylinder. 2. The cylinder selection means determines that a cylinder having a larger integrated value has a higher cylinder priority, and selects a cylinder to be preferentially closed. 2. The internal combustion engine with a cylinder deactivation function according to claim 1, wherein a cylinder having a smaller cylinder is determined to have a higher cylinder priority and is selected as a cylinder to be preferentially restored.