JPH039291B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a valve switching control device for an engine that controls the number of cylinders and performs partial cylinder operation by suspending 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.
(Japanese Patent Laid-Open No. 55-1648, Japanese Patent Laid-open No. 57-38639) As an example of this type of engine, when cutting fuel supply to some cylinders in the light load range or idling range, As shown in FIG. 2, a system is known that restricts the opening operation of the intake valve 1 and exhaust valve (not shown) of the cylinder (inactive cylinder).

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.

The same valve mechanism as described above is provided for the exhaust valve (not shown). Therefore, by operating the actuator 15 according to the operating conditions of the engine, the intake and exhaust actions of the corresponding cylinder on the idle side are regulated.
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 ignition current to the spark plug of the cylinder on the idle side 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, if intake air is trapped in the cylinder on the idle side in this way, when returning from partial cylinder operation to normal operation (all cylinder operation), depending on the switching timing of the intake and exhaust valves, the intake air may remain unused. There was a problem that the exhaust gas composition was deteriorated because it was sometimes discharged into the exhaust system.

In addition, there was a problem in that exhaust gas after combustion could be trapped in the cylinder on the idle side, and this could flow backwards through the intake valve when returning to full-cylinder operation, potentially worsening the combustion state.

This invention was made with attention to such problems, and it provides a means for detecting the crank angle of the engine, and switches the operation of the intake and exhaust valves based on this crank signal, thereby achieving optimal switching. Valve switching that allows smooth switching of the number of cylinders while maintaining good engine performance by setting the timing and preventing unburned intake air from flowing into the exhaust system and burned gas from flowing back into the intake system. The purpose is to provide a control device.

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 amount of intake air as engine load state detection means and a throttle valve that detects the opening degree of the throttle valve 20 are connected to the intake passage 18 that connects to the idle cylinder #2 and the operating cylinder (not shown). A valve sensor 21 is interposed, and a fuel injection valve 23 (a carburetor may be used) 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 angle sensor 27 is attached to the distributor 25 as means for detecting the crank angle. The crank angle sensor 27 generates a pulse signal A at each exhaust top dead center of each cylinder, and is set to generate a wide pulse when a specific cylinder is selected.

This pulse signal A, the intake air amount signal, the throttle valve opening signal, the rotational speed signal from the rotation sensor (not shown), the water temperature signal from the cooling water temperature sensor 28, etc. are connected to input/output circuits (I/O )34,
The data is input to a control circuit 29 that includes a central processing circuit (CPU) 31, a read-only memory circuit (ROM) 32, and a readable/writable memory circuit (RAM) 33.

Then, in response to the pulse signal A, the control circuit 29 detects and discriminates the operating conditions and load condition of the engine from each operating signal at every predetermined crank angle, and also controls the fuel injection valve 23 with an injection signal B based on these. The switch 30 on the primary side of the ignition coil 26 is turned on and off in response to the ignition signal C to control the ignition operation, and the actuator 15 is switched and activated in response to the valve control signal D to switch the intake of cylinder #2 on the idle side. , controls the operating states of the exhaust valves 1 and 17.

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 rest 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.

Crank angle sensor 2 generated at each exhaust top dead center
Based on the pulse signal A from 7, each cylinder #1~
#4 operating order (ignition order #1-#3-#4-
#2), an injection signal corresponding to the intake air amount etc. is sequentially commanded to each fuel injection valve 23 so as to achieve the optimum fuel injection amount, and the fuel injection timing is set, for example, at the beginning of each intake stroke. Set.

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 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 cylinders #2 and #3 on the idle side perform normal opening and closing operations, respectively.

In addition, E responds to the falling edge of pulse signal A,
3 shows an interrupt signal that instructs the control circuit 29 to detect engine operating conditions, etc.

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

Based on the intake air amount signal, rotation speed signal, etc., in the engine's light load range or idling range, the injection signal B to the fuel injection valve 23 corresponding to cylinders #2 and #3 is cut off, and the corresponding ignition signal is also cut off. Signal C is cut.

Then, the valve control signal N turns ON, and each actuator 15 operates, and the opening operations of the intake and exhaust valves 1 and 17 of the cylinders #2 and #3 on the idle side are regulated, and the intake and exhaust operations are stopped.

At this time, both the intake and exhaust valves 1 and 17 are kept closed, but for example, if a carburetor is used as the fuel supply system, the intake valve 1 may be configured to open somewhat at the end of its intake stroke. good.

As a result, full-cylinder operation and partial-cylinder operation are performed, and FIG. 6 shows control commands and timing charts when switching from full-cylinder operation to partial-cylinder operation.

In response to the pulse signal A from the crank angle sensor 27, if a light load region etc. is determined at point A from the intake air amount signal, rotation speed signal, etc., action is taken from cylinder #3 where the intake stroke ends at point A. The ignition signal C and injection signal B are cut off, and the valve control signal D is also turned ON. Then, in response to the pulse signal A output at the end of the intake stroke of the next cylinder #2 (point B), the ignition signal C and injection signal B corresponding to cylinder #2 are cut off, and the valve control signal D is turned on. can be switched to

In addition, when it is determined that the light load area etc. is at point B,
Cylinder #2 precedes cylinder #3 and reaches point C and D.
In the case of points, the above-mentioned control is performed from points A and B, which are close to these points. The dotted line parts of injection signal B and ignition signal C indicate the cut-off state, and the intake and exhaust valves 1 and 1
The shaded area M in 7 indicates the switching region of the operation.

In this case, there is a response delay from the judgment of the light load range etc. to the issuance of each control command, but in particular, in order to avoid overlapping valve switching commands in the list of intake valve 1, it is necessary to The valve control signal D is set to turn ON after a certain period of time. Specifically, an angle sensor (not shown) that generates a pulse every several degrees of crank angle is used together with the crank angle sensor 27, and in response to this signal, the valve control signal 2 is turned ON by a predetermined pulse. delay. Alternatively, a timer (not shown) may be provided,
It is configured to delay by a predetermined time.

That is, when switching to partial cylinder operation, the combustion exhaust in the cylinders #2 and #3 on the inactive side, which had been operating up until then, is cleanly discharged from the exhaust valve 17, and the fuel and fresh air supplied during the intake stroke are discharged cleanly. The proper air-fuel mixture is trapped in cylinders #2 and #3 in an unburned state.

On the other hand, FIG. 7 shows control commands and timing charts when returning from partial cylinder operation to full cylinder operation.

When it is determined that the light load range has entered the high load range, for example, at point A, synchronizing with pulse signal A, from cylinder #3 whose intake stroke ends at point A,
The supply of the corresponding ignition signal C and injection signal B is resumed, and after a predetermined crank angle (predetermined time), the valve control signal D is also switched OFF. Then, the supply of ignition signal C and injection signal B to cylinder #2 is restarted, and valve control signal D is switched to OFF.
Further, at point B, cylinder #2 takes the lead, and at points C and D, control is performed from points A and B, which are close to these points.

Therefore, when returning to full-cylinder operation, the unburned air-fuel mixture trapped in the idle cylinders #2 and #3 is necessarily burned in the expansion stroke and then exhausted from the exhaust valve 15 as described above. Ru. The combustion cycle then continues from the next intake stroke.

In this way, by performing each control based on the pulse signal A of the crank angle sensor 27, the ignition, fuel injection, and operation switching timing of the intake and exhaust valves 1 and 17 can be optimally set. When transitioning to cylinder operation, the idle cylinder #2,
An unburned air-fuel mixture (appropriate air-fuel ratio) is trapped in #3, and when returning to full-cylinder operation, the air-fuel mixture is combusted before operation of cylinders #2 and #3 is started.

Therefore, when switching the number of cylinders, unburned air-fuel mixture is discharged and disturbs the exhaust composition, and exhaust gas after combustion flows back into the intake system, worsening sintering in active cylinders #1 and #4. It is possible to accurately switch between full cylinder operation and partial cylinder operation while maintaining good engine and exhaust conditions.

In addition, by trapping the air-fuel mixture in cylinders #2 and #3 on the idle side, torque fluctuations during partial cylinder operation are effectively reduced, and since this air-fuel mixture is combusted while returning to full-cylinder operation, smooth operation is achieved. This significantly improves engine response during acceleration.

Note that the intake and exhaust valves 1,
17 is determined by taking into consideration the switching response time. For example, if the exhaust valve 17 cannot be switched in time, separate operation switching actuators 15 are provided for the intake and exhaust valves 1 and 17, and the exhaust valve 1
Set the switching of 7 early.

FIGS. 8 and 9 show other embodiments of the present invention, which are applied to a six-cylinder engine and use a carburetor as the fuel supply device. However, #1 to #3 are operating cylinders,
#4 to #6 are the cylinders on the idle side, and the operating order is #1 to #5.
-#3-#6-#2-#4, FIG. 8 shows each timing chart during all cylinder operation, and FIG. 9 shows a timing chart when switching from partial cylinder operation to all cylinder operation.

A pulse signal A is generated from the crank angle sensor 27 at each exhaust top dead center of each cylinder, and in response to this, the operating state of the engine is detected and determined. For example, when switching from partial cylinder operation to full cylinder operation, if the light load range is entered at point a, the cutoff of the ignition signal c to cylinder #4, which is in the middle of the intake stroke, is released, and the next point b or In response to the pulse signal A at the next point c, the corresponding valve control signal D is switched OFF. After that, the cutoff of the ignition signal C to cylinder #5 is released at points b to d, and to cylinder #6 at points d to f, and c, d
At point #5, f, and point g, the valve control signal corresponding to cylinder #6 is switched OFF. If the engine enters the light load range at points b and c, similar control is performed starting from cylinder #5.

When the engine speed is relatively high, the switching response time of the intake and exhaust valves 1 and 17 becomes relatively long, so it is preferable to set each control early as shown in FIG. 10.

According to this, there is no particular need for fuel cutoff control, etc., making it easy to perform, and the above control can be performed only based on the pulse signal A output at each exhaust top dead center. Optimal switching control of the number of cylinders can be performed without using angle sensors or timers.

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 operations of the intake and exhaust valves of some cylinders,
A means for detecting the load state of the engine and a means for detecting the crank angle are provided, and the suction and intake based on the detected load are
Since the exhaust valve operation switching is controlled in synchronization with the crank signal, the optimal switching timing for ignition, fuel supply, etc. can be set, and the number of cylinders can be switched accurately while maintaining good driving performance and exhaust performance. There is an effect that it can be done.

[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. 7 to 7 are timing charts showing respective signal waveforms and operating states of the intake and exhaust valves of the present invention, and FIGS. 8 to 10 are timing charts of other embodiments of the present invention, respectively. 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,
26...Ignition coil, 27...Crank angle sensor, 29...Control circuit, 30...Switch.

Claims (1)

[Claims] 1. Means for detecting the load state of an engine in a multi-cylinder engine equipped with a dormant cylinder whose operation is suspended by restricting the opening operation of the intake valve and exhaust valve in a light load range, etc., and an operating cylinder which is constantly operated. , a means for detecting a crank angle is provided, and the load condition is detected at every predetermined crank angle according to the crank signal, and regulation and release of the opening operation of the intake and exhaust valves based on the detected load are synchronized with the crank signal. What is claimed is: 1. A valve switching control device for an engine that controls the number of cylinders, comprising a control circuit that issues commands based on the number of cylinders.