JPH0338414B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder number switching control device for a cylinder number controlled engine that performs partial cylinder operation by suspending the operation of some cylinders in a light engine load range or the like.

In general, fuel efficiency tends to improve when an engine is operated under a high load. For this reason, in a multi-cylinder engine, when the engine load is light, fuel supply to some cylinders is cut off to stop operation. An engine with controlled number of cylinders was devised that relatively increases the load on the remaining active cylinders by that amount, thereby improving overall fuel efficiency in the light load range.

As an example of this type of engine, conventionally, when cutting fuel supply from the fuel injection valve to some cylinders in the light load range or idling range, as shown in Figs. Intake valve 1 of side cylinder)
Also known are devices that restrict the opening operation of an exhaust valve (not shown).

In the figure, 2 is a cylinder head, 3 is a rocker arm, 4 is a rocker shaft, 5 and 6 are brackets that support the rocker shaft 4 on the cylinder head 2, and 7 is a camshaft.

This camshaft 7 has a valve spring 8
The first cam 9 is provided with a profile for opening and closing the intake valve 1 via the Rocker arm 3 during the intake stroke during operation, and the first cam 9 has a perfect circular shape that is the same shape as the base circle of this cam 9. A second cam 10 is formed adjacent to the second cam 10.

On the other hand, the rocker arm 3 is supported so that it is not only swingable relative to the rocker shaft 4 but also movable in the axial direction between the two brackets 5 and 6.

A switching ring 11 that is slidable in the axial direction between the rocker arm 3 and one of the brackets 5 is fitted into the rocker shaft 4. The axial positioning is performed according to the tension balance between the spring 12 of the bracket 6 and the second spring 13 interposed between the bracket 6 of the other bracket.

This switching ring 11 is driven by an actuator 15 composed of a solenoid or a hydraulic cylinder through a rod 14, and when the actuator 15 is not in operation, the intake valve 1 is opened and closed according to the first cam 9. rotsker arm 3
The initial position of is set.

When the actuator 15 is operated, the switching ring 11 moves toward the bracket 6 due to its driving force, and as the springs 12 and 13 are compressed, the rocker arm 3 is pushed, and its follower portion 16 moves toward the base circle of the cam 9. the second cam 1 while in the area
Transfer to 0. The second cam 10 is the first cam 9
Since it has a perfect circular shape with the same diameter as the base circle, the rocker arm 3 does not swing in this state, and therefore the intake valve 1 is held closed and in a resting state.

Although not shown, the exhaust valve is also provided with a valve mechanism similar to the above, and therefore the actuator 15
By operating the engine according to the operating conditions of the engine, the intake and exhaust actions of the corresponding cylinder on the inactive side are regulated and controlled.

The operation of the actuator 15, that is, the regulation of the opening operation of the intake valve 1 and the exhaust valve, is controlled by a command from a control circuit (not shown), such as a load sensor or rotation sensor (not shown) that detects the operating conditions of the engine. In response to signals from the engine, etc., the intake and exhaust valves are kept closed in the light load range or idling range. At this time, the fuel injection valve corresponding to the idle cylinder is kept fully closed, and
Similarly, the ignition current to the spark plug is cut off.

In this way, the supply of fuel and fresh air to the cylinders on the idle side is cut off to suspend their operation, and partial cylinder operation is performed by operating only the remaining cylinders on the active side.

According to this, the intake air trapped in the cylinder on the idle side is repeatedly compressed and expanded, which not only improves fuel efficiency, but also suppresses increases in torque fluctuations and rotational fluctuations during partial cylinder operation to a relatively low level. There is an advantage.

However, even if the intake air is trapped in the cylinder on the idle side in this way, blow-by to the crankcase side occurs during repeated compression and expansion, and the compression pressure in the cylinder gradually decreases, resulting in a drop in the compression pressure in the cylinder. There was a problem in that the effect of suppressing torque fluctuations etc. could not be obtained, and instead, irregular vibrations increased.

Also, depending on the timing of fuel cutoff of the fuel injection valve when transitioning to partial cylinder operation, and the timing of regulating the opening operation of intake and exhaust valves, the exhaust gas after combustion may be trapped in the cylinder on the idle side. This becomes blow-by gas and has a negative effect on the engine oil.
There was a concern that carbon etc. would deteriorate and adhere to the cylinder wall, causing stains.

This invention was made with a focus on these problems, and it cuts off the fuel supply before the intake stroke when transitioning to partial cylinder operation, and restricts the opening operation of the intake and exhaust valves immediately after the intake stroke. The above-mentioned problem is solved by confining only fresh air (air) in the cylinder on the idle side and replenishing the fresh air in a timely manner to keep the compression pressure in the cylinder stable. The purpose is to provide a multiple switching control device.

In order to achieve the above object, the present invention has two cylinders in which the fuel supply from the fuel injection valve is cut off under light load, etc., and the opening of the intake valve and exhaust valve is regulated to suspend operation, and the other in which the cylinder is inactive at all times. In a cylinder number control engine having an operating cylinder that continues to operate, the above-mentioned means for supplying fresh air to the inactive cylinder when the operation is stopped, and a fuel injection valve of the corresponding inactive cylinder before the intake stroke when the operation is stopped. A control means is provided to cut off the fuel supply to the engine and restrict the opening operations of the intake and exhaust valves immediately after the intake stroke.

Further, in the present invention, the control means is configured to supply a predetermined amount of fuel to the cylinder on the idle side, prior to the return of the opening operation of the intake and exhaust valves when the operation is restarted, and in synchronization with the fresh air supply. In addition, improvements are being made in drivability and exhaust performance upon resumption of operation.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 3 is a cross-sectional view showing an embodiment of the present invention.
#2 is the cylinder on the idle side, 1 and 17 are the intake valve and exhaust valve,
Reference numeral 15 denotes an actuator (solenoid) that switches the operating states of the intake and exhaust valves 1 and 17.

An air flow sensor 19 that detects the intake air amount and a throttle valve sensor 21 that detects the opening degree of the throttle valve 20 are interposed in the intake passage 18 connected to the idle cylinder #2 and the active cylinder (not shown). A fuel injection valve 23 serving as a fuel supply device is provided in the intake port 22 corresponding to each cylinder.

Further, 24 is a spark plug, 25 is a distributor, 26 is an ignition coil, and a crank sensor 27 for detecting the crank position is attached to the distributor 25. This crank sensor 27 generates a pulse signal A at each exhaust top dead center of each cylinder, and is set so that it generates a wide pulse when a specific cylinder is selected.

Then, this signal A and the intake air amount signal,
Throttle valve opening signal and rotation sensor (not shown)
The rotation speed signal from the cooling water temperature sensor 28, the water temperature signal from the cooling water temperature sensor 28, etc. are input to the control circuit 29, and the control circuit 2
Based on these signals, 9 drives and controls the fuel injector 23 with the injection signal B, and controls the primary side switch 3 of the ignition coil 26 with the ignition signal C.
0 intermittently to control the ignition operation, and the actuator 15 is switched in response to the valve control signal D to control the operating state of the intake/exhaust valves 1 and 17 of the idle cylinder #2.

This control circuit 29 is a central processing circuit (CPU)
31, a read-only memory circuit (ROM) 32, a readable/writable memory circuit (RAM) 33, and an input/output circuit (I/O) 34.

FIG. 4 shows the signal waveforms during all-cylinder operation and the operating states of the intake and exhaust valves 1 and 17 on the idle side. However, in the example applied to a 4-cylinder engine, #1, #4
is the active cylinder, and #2 and #3 are the idle cylinders.

Based on the pulse signal A from the crank sensor 27 generated at each exhaust top dead center, each cylinder #1~
#4 operating order (ignition order #1-#3-#4-
According to #2), an injection signal corresponding to the amount of intake air, etc. is sequentially commanded to each fuel injection valve 23 so that the optimum fuel injection amount can be obtained, and the fuel injection timing is set at the beginning of each intake stroke. be done.

Similarly, the ignition signal C is sequentially commanded based on the pulse signal A, and the ignition timing is set by the distributor 25 so that the optimum ignition is performed near the compression top dead center of each cylinder #1 to #4. .

Further, the valve control signal D is OFF, and each actuator 15 is maintained at the initial position, so that the intake and exhaust valves 1 and 17 of the idle cylinders #2 and #3 perform normal opening and closing operations, respectively.

On the other hand, FIG. 5 shows signal waveforms during partial cylinder operation in which the operations of cylinders #2 and #3 are suspended, and the operating states of the intake and exhaust valves 1 and 17.

Based on the intake air amount signal and rotation speed signal, cylinder #2,
The injection signal B to the fuel injection valve 23 corresponding to #3 is cut off to maintain the fully closed state, and the corresponding ignition signal C is also cut off.

Then, the valve control signal D is turned ON, and each actuator 15 operates, and the opening operation of the intake/exhaust valves 1 and 17 of the idle cylinders #2 and #3 is regulated.

At this time, the exhaust valve 17 is kept closed, but the intake valve 1 is configured to open somewhat at the end of its intake stroke, as shown. That is, as shown in FIG. 6, the second cam 10 corresponding to the intake valve 1
The lift portion 9a of the first cam 9 is placed at the predetermined position.
The lift section 10 has a much smaller overall height and operating angle.
A is provided to form a means for supplying fresh air to the cylinder intakes #2 and #3 on the idle side.

As a result, all-cylinder operation and partial-cylinder operation are performed, and when transitioning from this all-cylinder operation to partial-cylinder operation, the fuel supply to the fuel injection valves 23 of the corresponding idle cylinders #2 and #3 is stopped before the intake stroke. Immediately after the suction stroke, the intake and exhaust valves 1 and 1 are
Control means (control circuit 29) for regulating the opening operation of 7
is provided.

Specifically, based on the pulse signal A from the crank sensor 27 input to the control circuit 29,
Injection signal (b) and ignition signal (c) for cylinders #2 and #3 on the idle side are cut off, and valve control signal (d) is switched to ON.

FIG. 7 shows each timing chart at this time. Based on the intake air amount signal from the air flow sensor 19, the rotation speed signal from the rotation sensor, etc.
For example, when a light load region is determined at point A, the pulse signal A of the crank sensor 27 is output during the exhaust stroke of cylinder #2 near point A, that is, at the exhaust top dead center of cylinder #4. Before the intake stroke of cylinder #2, the corresponding injection signal RO is cut off, cutting off the fuel supply. Then, in response to the pulse signal A, the corresponding ignition signal C is cut off immediately after the intake stroke, and the valve control signal D is switched ON.

Cylinder #3 is delayed from this, and in response to pulse signal A output at the exhaust top dead center of cylinder #1, injection signal B is also cut off before the intake stroke (during the exhaust stroke), and immediately after the intake stroke. The ignition signal C is cut off, and the valve control signal D is switched ON.

Further, when the point A is close to the exhaust stroke of cylinder #3, the above-described control is performed on cylinder #3 earlier than cylinder #2.

That is, when switching to partial cylinder operation, the fuel exhaust in the cylinders #2 and #3 on the inactive side, which had been in operation until then, is cleanly discharged from the exhaust valve 17, and the supply of fuel is cut off in the next intake stroke, Only fresh air is guided from the intake valve 1 into the cylinders #2 and #3. In this state, the ignition is stopped, the opening of the intake and exhaust valves 1 and 17 is restricted, and partial cylinder operation is started while supplying fresh air to the idle cylinders #2 and #3 as described above. be.

Note that FIG. 8 shows each timing chart when returning from partial cylinder operation to full cylinder operation. For example, when entering a high load area at point B from a light load area, etc.,
In response to pulse signal A corresponding to the end of the intake stroke of cylinder #2 (or #3) near point B, the supply of the corresponding ignition signal C and injection signal B resumes immediately after the intake stroke of cylinder #2. and valve control signal D is switched OFF. Then, the supply of the ignition signal C and the injection signal B to the cylinder #3 (or #2) is resumed, and the valve control signal D is switched OFF.

However, prior to switching of the valve control signal D, a predetermined amount of fuel is injected and supplied to the cylinder on the idle side so as to be synchronized with the timing when the intake valve 2 of the cylinder on the idle side is slightly lifted. This fuel is sucked into the cylinder together with the make-up air during the small lift, mixes with the air in the cylinder, and is ignited and combusted immediately after the return to operation. Incidentally, the fuel injection is performed by the crank angle sensor 27 after the decision to switch the number of cylinders is made at point B.
This is performed only once prior to each control operation while referring to the pulse signal A. Furthermore, the broken lines in the middle of the signals B and D represent the original injection and ignition timings, respectively.

With such fuel supply control, when returning to all-cylinder operation, responsive and smooth operation of the idle cylinders #2 and #3 can be obtained, and acceleration performance and the like can be improved. Also, at the time of return, the idle side cylinder #2,
Since the fresh air in #3 is not directly discharged to the exhaust system, the conversion efficiency can be maintained well when a three-way catalyst is used.

With this configuration, when transitioning from full cylinder operation to partial cylinder operation, the idle side cylinder #2,
Fresh air is always trapped in #3, which prevents engine oil from deteriorating even if blow-by occurs, and prevents unburned gas, gasoline in the combustion exhaust, tar, etc. from adhering to the cylinder wall and staining it. be done.

During partial cylinder operation, the idle side cylinder #2,
Since fresh air is replenished to #3 at each end of the suction stroke, even if it decreases during repeated compression and expansion, it can be filled and a stable high compression pressure can be maintained at all times. As a result, torque fluctuations and rotational fluctuations during partial cylinder operation can be sufficiently reduced, and good drivability can be obtained.

In addition, the control of each of the above-mentioned signals is performed by the crank sensor 2.
The command is given based on the pulse signal A of 7,
The timing is selected in consideration of the response time of the intake/exhaust valves 1, 17, and if, for example, the switching of the exhaust valve 17 cannot be done in time, separate operation switching actuators 15 are provided for the intake/exhaust valves 1, 17, respectively.
The switching of the exhaust valve 17 may be set early.

As explained above, according to the present invention, in a cylinder number control engine in which partial cylinder operation is performed by regulating the opening operation of the intake and exhaust valves of some cylinders,
Fresh air (air) enters the cylinder that is stopped during partial cylinder operation.
This method prevents contamination of the inside of the cylinder and other parts due to blow-by, sufficiently suppresses torque fluctuations during partial cylinder operation, and significantly improves engine performance and driving performance. It has the effect of being able to improve.

Furthermore, in the present invention, when returning from partial cylinder operation to full cylinder operation, a predetermined amount of fuel is supplied to the cylinder on the idle side in advance, and this is mixed with the air that had been introduced into the cylinder and combusted. As a result, it is possible to improve the response, acceleration, and exhaust performance of the engine when returning to full-cylinder operation.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of a valve mechanism that regulates the opening operation of an intake valve or an exhaust valve, FIG. 2 is a schematic front view thereof, FIG. 5, 7, and 8 are timing charts showing signal waveforms and operating states of the intake and exhaust valves of the present invention, respectively, and FIG. 6 is a partial perspective view of the intake valve cam. 1...Intake valve, 3...Rotzker arm, 9...
First cam, 10... Second cam, 11... Switching ring, 15... Actuator, 17... Exhaust valve, 19... Air flow sensor, 20... Throttle valve,
21... Throttle valve sensor, 23... Fuel injection valve, 24
...Spark plug, 25...Distributor,
27... Crank sensor, 29... Control circuit, 3
0...Switch.

Claims (1)

[Claims] 1 Equipped with a dormant cylinder that stops operating when the fuel supply from the fuel injection valve is cut off under light loads, etc., and the opening of the intake valve and exhaust valve is restricted, and an active cylinder that continues to operate at all times. In the cylinder number control engine, there is a means for supplying fresh air to the cylinder on the idle side when the operation is suspended, and a means for cutting off the fuel supply to the fuel injection valve of the corresponding cylinder on the idle side before the intake stroke when the operation is suspended, and immediately after the intake stroke. Similarly, the opening operation of the intake and exhaust valves is regulated, and when the operation resumes, the intake and exhaust valves are
A control device for switching the number of cylinders, comprising: control means for supplying a predetermined amount of fuel to the cylinder on the idle side prior to the return of the opening operation of the exhaust valve and in synchronization with the fresh air replenishment.