JPS5932641A - Engine control device - Google Patents

Abstract

PURPOSE:To prevent the pressure in cylinders from becoming too high, by providing a timer circuit for producing a signal for a prescribed while from the time when switching from ''full-cylinder operation'' to ''partial-cylinder operation'' is effected in a ''partial-cylinder operation'' maintaining section of an engine which is capable of switching the mode of operation from ''full-cylinder operation'' to ''partial-cylinder operation'' by controlling the number of cylinders in operation. CONSTITUTION:Timer circuits 8, 11 start measurement of time at the rising time of signals applied to them. In switching the mode of operation of an engine from four-cylinder operation to two-cylinder operation, the level of a signal S1 is changed from low (full-cylinder operation) to high (partial-cylinder operation), and resultantly, the level of an output signal S2 of an OR-circuit 4 is rendered high. By the ''high level'' of the signal S2 and that of a signal S6 produced from a ''full-cylinder operation'' maintaining timer circuit 8 via a NOT-circuit, the level of a valve stopping signal S3 produced from an AND-circuit 5 is rendered high. In response to this, a ''partial-cylinder operation'' signal is applied to a valve stopping means 6, so that switching from ''full-cylinder operation'' to ''partial-cylinder operation'' is effected at an appropriate timing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a deactivated engine that can control the number of operating cylinders to perform all-cylinder operation (all-cylinder operation) or partial cylinder operation (deactivated cylinder operation). The present invention relates to a device for controlling switching to an all-cylinder operating state.

In conventional deactivated engines, for example, during low-load operation, some of the cylinders are turned off in order to increase combustion efficiency and prevent the generation of harmful gases, or to improve fuel efficiency by increasing the load factor and reducing pumping loss. The engine is operated with the cylinders in a deactivated state.

By the way, for example, in a 4-cylinder engine, switching from a 4-cylinder operating state (all-cylinder operating state) to a 2-cylinder operating state (cylinder-deactivated operating state), and from a 2-cylinder operating state to a 4-cylinder operating state is accomplished by changing the intake and exhaust valves. In a conventional control device that performs control by stopping cylinders b and c, if intake valve b stops before exhaust valve c when the cylinders are put into a deactivated operation state, the pressure inside cylinder a will not become high, so intake valve b will stop. It also operates without any problems, and there is no backfire caused by blowback.

However, in a conventional cylinder-deactivated engine, when stopping intake valve b and exhaust valve c, the order of stop priority for intake valve b and exhaust valve c is not defined. When the exhaust valve c stops before the intake valve b, the combustion gas in the cylinder a is not exhausted but is trapped in the cylinder a, and the pressure inside the cylinder a becomes high. [See Figure 1 (b)] When a cylinder in a dormant state has a high pressure inside its cylinder a, the trapped combustion gas moves between the piston d and the inner wall of cylinder a as the piston d reciprocates. It gradually slips out into the crank room from between.

However, in conventional cylinder deactivation engine control devices, the cylinders that are switched from the operating state to the cylinder deactivation state are in a high pressure state, and before this high pressure is released, a differential signal for canceling cylinder deactivation (all cylinders state If intake valve b is released when a switching signal (switching signal) to intake valve b is transmitted, the following problems will occur.

In other words, the extremely high pressure inside cylinder a must be overcome to operate intake valve b, which causes problems such as damage to rocker arm e and backfire caused by blowback when the intake valve is activated. .

This damage to the rocker arm e occurs when the rocker arm load exceeds the rocker arm fatigue limit A, as shown in Figure 2. Figure 2 shows the rocker arm load versus interval (number of ignition pulses). It shows the interval and time (m sec
) shows the relationship when the engine speed is 3000 (rpm).

Therefore, as can be seen from FIG. 2, in the conventional cylinder-deactivated engine control device, for example, when the engine speed is 3000,
(rpm), if a cylinder that has been switched from an operating state to a deactivated state creates a high pressure state in cylinder a, control is performed to return it to an operating state again within 180 (m sec) from the time of switching. , there is a problem that the load applied to the rocker arm e exceeds the rocker arm fatigue limit A.

The present invention aims to solve these problems, and by maintaining a cylinder-deactivated operation state for a predetermined period of time, it is possible to prevent the inside of the cylinder from becoming high-pressure when the intake valve starts operating. The object of the present invention is to provide a cylinder deactivation engine control device.

For this reason, the deactivated engine control device of the present invention switches some of the cylinders between an active state and a deactivated state in a deactivated engine that can perform full cylinder operation or partial cylinder operation by controlling the number of activated cylinders. In order to control, the cylinder deactivation determining unit is provided with a deactivation determining unit capable of transmitting an activation signal or deactivation signal to the cylinder deactivation means of the same cylinder, and the activation signal from the cylinder deactivation determination unit is transmitted for some of the cylinders in the cylinder deactivation state. In order to maintain the deactivated state of the same cylinder with priority even when the cylinder is deactivated, a deactivated cylinder maintenance section is provided which can send a deactivated cylinder maintenance signal to the cylinder deactivation means. It is characterized by having a cylinder deactivation maintenance timer circuit which transmits the cylinder deactivation maintenance signal for a predetermined period of time from the time when some cylinders are switched from the operating state to the cylinder deactivation state.

Hereinafter, an ignition timing control device for a deactivated engine as an embodiment of the present invention will be explained with reference to the drawings. FIG. 3 is a graph showing its operation, FIG. 4 is a block diagram showing its overall configuration, and FIG. Its electrical circuit diagram, Figures 6(a) to (i)
) are graphs showing the effect.

In order to control such a cylinder deactivation engine, as shown in FIGS. 4 and 5, a cylinder deactivation determination circuit (deactivation determination section) 1 is provided. In response to a signal indicating the operating state such as an engine load signal or a water temperature signal from the sensor 3, an activation signal or cylinder deactivation signal is transmitted to a valve stop device 6 as cylinder deactivation means.

Then, the valve stop device 6 controls some cylinders (hereinafter referred to as;
It's called a "control cylinder." ) are deactivated and activated at appropriate times.

In addition, even if a cylinder deactivation signal (S2 is at high level) is transmitted from the cylinder deactivation determination circuit 1 to a controlled cylinder in an operating state, the valve stop device 6 An operation maintenance section 15 is provided that can send an operation maintenance signal (S6 is low level) to the cylinder. An operation maintenance timer circuit 8 is provided which transmits a maintenance signal.

Furthermore, even if an activation signal (S1 is low level) is sent from the cylinder deactivation determination unit 1 to a controlled cylinder in a deactivated state, the valve is stopped in order to maintain the deactivated state of the controlled cylinder with priority. A cylinder deactivation maintaining section 14 capable of transmitting a cylinder deactivation maintaining signal (S9 is high level) to the device 6 is provided. A cylinder deactivation maintenance timer circuit 11 is provided which transmits a cylinder deactivation maintenance signal for a predetermined period of time.

The operation maintenance unit 15 stores vehicle speed (including engine rotation speed).
A signal Sa for increasing/decreasing the transmission interval of the operation maintenance signal is supplied from a vehicle speed determination circuit 9 that determines the vehicle speed (or engine rotation speed). (not shown), when the vehicle speed signal is above a predetermined value (during high speed driving), the vehicle speed determination signal Sa is set to high level, and when it is below the predetermined value (during low speed driving), The signal Sa is set to low level.

Incidentally, the cylinder deactivation maintaining section 14 receives the cylinder deactivation signal or activation signal S1 from the cylinder deactivation determination circuit 1 at one input terminal of the OR circuit 4, and also sends the valve stop signal S3 to the controlled cylinder to the cylinder deactivation maintenance timer circuit. The output signal S9 of the timer circuit 11 for maintaining cylinder deactivation is sent to the other input terminal of the OR circuit 4.

Further, the operation maintaining section 15 transmits the cylinder deactivation signal or the activation signal S1 from the cylinder deactivation determining circuit 1 to the OR circuit 4 of the cylinder deactivation maintaining section 14.
is received at one input terminal of the AND circuit 5 via
The valve stop signal S3 to the controlled cylinder is received via the knot circuit 7 at the input end of the operation maintenance timer circuit 8, and the output signal of the operation maintenance timer circuit 8 is received via the knot circuit 10. , and is sent to the other input terminal of the AND circuit 5.

Note that each timer circuit 8, 11 is a circuit that starts measuring time when the signal input to each circuit 8, 11 rises, and the details of the circuit including these timer circuits 8, 11 are described in the fifth section. These are indicated by reference numerals 8, 10 and 14' in the figure.

Since the deactivated engine control device of the present invention is configured as described above, when switching from the four-cylinder operating state (all-cylinder operating state) to the two-cylinder operating state (deactivated-cylinder operating state) (the reference numerals shown in FIG. 6 t1), the signal S1 is at low level (see t1).
As a result, the output signal S2 of the OR circuit 4 changes from the cylinder deactivation signal) to a high level (operation signal) (see FIG. 6(a)).
becomes a high level [see FIG. 6(b)], and the high level of this signal S2 and the high level of the signal S6 from the operation maintenance timer circuit 8 via the NOT circuit 10 cause the AND circuit 5 to The valve stop signal S3 from becomes high level.

[See FIG. 6(c)] When this valve stop signal S3 becomes high level, a cylinder deactivation signal is sent to the valve stop device 6, and the controlled cylinder changes from the operating state to the cylinder deactivation state at an appropriate timing. Switching control is performed.

Furthermore, the cylinder deactivation maintenance signal (signal S9 is at a high level) is maintained at the cylinder deactivation maintenance section 14 for the cylinder deactivation maintenance time Tb (here, 0.2 seconds) from the switching time t1 from the four cylinder operating state to the two cylinder operational state. ' is transmitted from the comparator 13 to the AND circuit 16. [See FIG. 6(i)] This cylinder deactivation maintenance time Tb is when the valve stop signal S3 is at a high level and the output signal S8 from the comparator 13 is
This is the time during which the AND circuit 16 is at a high level when S is at a high level, and corresponds to the time during which the valve stop signal S3 is maintained at a high level.

[See Figure 6 (h)] The output signal S8 from the comparator 13 becomes high level from the time when the valve stop signal S3 switches from low level to high level until the cylinder deactivation maintenance time Tb elapses. It is.

That is, when the valve stop signal S3 is at a low level, the transistor Tr1 as the NOT circuit 7 is turned on, the signal S4 is at a high level, and the transistor Tr2 is turned on, which causes the signal S7 to be at a low level. Then, this signal S7 and the reference voltage V2 are connected to the comparator 1.
3, and the output signal S8 of the comparator 13 becomes high level. [See Figures 6(d) and (g)] Furthermore, during the period from when the valve stop device S3 switches from low level to high level until the cylinder deactivation maintenance time Tb, the transistor Tr1 is turned off and the signal S4 is low. level. Therefore, the transistor Tr2 is turned off, the voltage S7 is gradually charged by the capacitor C2, and when the charged voltage S7 becomes lower than the reference voltage V2, the output signal S8 of the comparator 13 becomes high level.

During this cylinder deactivation maintenance time Tb, when a signal for switching from the 2-cylinder operating state to the 4-cylinder operational state is transmitted from the cylinder deactivation determination circuit 1 (time indicated by reference numeral t5 in FIG. 6), the 2-cylinder operating state is immediately 0 from the time of the immediately previous switching from the 4-cylinder operating state to the 2-cylinder operating state (time indicated by reference symbol t4 in FIG. 6) without switching from the cylinder operating state to the 4-cylinder operating state.
．． The cylinder remains inactive for 2 seconds.

With this cylinder deactivation maintenance signal, even if the exhaust valve stops first when the cylinder is deactivated, the cylinder deactivation state is maintained for at least 0.2 seconds, and the combustion gas trapped in the cylinder is released as the piston reciprocates. It escapes into the crank chamber from between the piston and the inner wall of the cylinder.

Therefore, in the control device of the present invention, as shown in FIG. 2, even when the engine speed is 3000 (rpm) or less and the cylinder is switched from the operating state to the deactivated state, the pressure inside the cylinder is high. The load applied to the rocker arm is within the rocker arm strength range below the rocker arm fatigue limit A, and the rocker arm is not damaged.

In addition, in this embodiment, the two-cylinder operating state (cylinder deactivated operating state)
When switching to a four-cylinder operating state (all-cylinder operating state) (see symbol t0 shown in Fig. 6), the signal S1 changes from a high level (cylinder deactivation signal) to a low level (operating signal), and as a result, the , the output signal S2 of the OR circuit 4 becomes low level, and the low level of this signal S2 and the high level or low level of the signal S6 from the operation maintenance timer circuit 8 via the NOT circuit 10 cause the AND circuit 5 The valve stop signal S3 from becomes low level. [Figure 6(c), (
See f)] As the valve stop signal S3 becomes low level in this way, an activation signal is sent to the valve stop device 6, and the controlled cylinder is controlled to switch from the deactivated state to the activated state at an appropriate timing. It is possible.

Furthermore, the operation maintenance signal (signal S is at a low level) is transmitted from the operation maintenance timer circuit 8 to the AND circuit 5 for the operation maintenance time Ta from the switching time t0 from the two-cylinder operation state to the four-cylinder operation state. It has become.

This operation maintenance time Ta changes according to the vehicle speed determination signal Sa from the vehicle speed determination circuit 9, and when this signal Sa is at a high level (during high-speed driving), the transistor Tr3 shown in FIG. is on and capacitor C
The discharge voltage S5 from the reference voltage V1 and the comparator 1 is shown by the solid line in FIG. 6(e).
2, and as a result, the signal S6 becomes low level for a period of time corresponding to the high vehicle speed, as shown by the solid line in FIG. 6(f).

Furthermore, when the vehicle speed determination signal Sa is at a low level (during low speed driving), the transistor Tr3 is turned off, and the discharge voltage S5 from the capacitor C1 becomes as shown by the broken line in FIG. 6(e). S5 is compared with the reference voltage V1 by the comparator 12, and as shown by the solid line and broken line in FIG. ) is at low level.

In other words, when the vehicle speed is high, the consumption rate of the accumulated fuel is high, so the maintenance time of the 4-cylinder state is shortened (here,
0.2 seconds) to prevent over-rich conditions; when the vehicle speed is low, conversely, the consumption rate of the accumulated fuel is small, so the 4-cylinder state is maintained for a long time (0.2 seconds). 2 seconds) to prevent an overrich condition.

During this operation maintenance time Ta, when a signal for switching from the 4-cylinder operating state to the 2-cylinder operating state is transmitted from the cylinder deactivation determination circuit 1 (time indicated by reference numeral t3 in FIG. 6), the 4-cylinder operating state is immediately activated.
0.2 seconds (during high-speed driving) from the time of switching from the 2-cylinder operating state to the 4-cylinder operating state (time indicated by reference numeral t2 in Fig. 6), instead of switching from the cylinder operating state to the 2-cylinder operating state. Or, for 2 seconds (when driving at low speed), all cylinders are kept in operation.

In addition, in the above embodiment, a monostable multivibrator may be used as each timer circuit.

Furthermore, this timer circuit connects the output end of a two-input AND circuit to the input end of a medium-stable multivibrator, and
An output signal is supplied from the output end of the medium-stable multivibrator to one input end of the input AND circuit via the NOT circuit, and the other input end of the two-input AND circuit is used as the output end of this timer circuit. The output end of the stable multivibrator may be configured as the output end of this timer circuit.

As detailed above, according to the deactivated engine control device of the present invention, it is possible to maintain the deactivated state of some cylinders for a predetermined period of time from the time when the activated state of some cylinders is switched to the deactivated state. Therefore, when the intake valve resumes operation due to switching from the operating state to the cylinder deactivation state, there is an advantage that it can sufficiently prevent the high pressure state in some cylinders from becoming high pressure state in the cylinder. This avoids problems such as damage to the rocker arm due to intake valve operation and backfire caused by blowback.

[Brief explanation of drawings]

Figures 1 (a) and (b) are both schematic diagrams showing the internal state of a cylinder that is deactivated in a conventional deactivated engine control system, and Figure 2 is a diagram showing the internal pressure of a cylinder that is deactivated. Figures 3 to 6 are graphs showing a deactivated engine control system as an embodiment of the present invention, Figure 3 is a graph showing its operation, and Figure 4 is its overall configuration. FIG. 5 is an electric circuit diagram thereof, and FIGS. 6(a) to (i) are graphs showing its operation. 1. Cylinder deactivation determination circuit as cylinder deactivation determination section, 2. Load sensor, 3. Water temperature sensor, 4. OR circuit, 5. AND circuit, 6. Valve stop device as cylinder deactivation means, 7・・Knot circuit, 8・・Timer circuit for maintaining operation, 9・・Vehicle speed judgment circuit, 10・・Knot circuit, 11・・Timer circuit for maintaining cylinder deactivation, 12, 13・・Comparator, 14, 14'・・・・deactivation Cylinder maintenance section, 15... Operation maintenance section, 16... AND circuit, A
...Rocker arm fatigue limit, C1, C2...Capacitor, Tr1, Tr2, Tr3...Transistor.

Claims (1)

[Claims] In a deactivated engine that can control the number of active cylinders to perform all-cylinder operation or partial cylinder operation, an activation signal is sent to the cylinder deactivation means for the cylinder in order to control switching of some of the cylinders between the activated state and the deactivated state. The cylinder deactivation determination unit is equipped with a cylinder deactivation determination unit capable of transmitting a cylinder deactivation signal, and even if an activation signal is transmitted from the cylinder deactivation determination unit for some of the cylinders in the deactivated state, the cylinder deactivation is given priority over this. In order to maintain the cylinder state, a cylinder deactivation maintaining section capable of transmitting a cylinder deactivation maintenance signal to the cylinder deactivation means is provided, and the cylinder deactivation maintaining section changes the cylinder state from the operating state of some of the cylinders to the cylinder deactivation state. A cylinder deactivation engine control device comprising a cylinder deactivation maintenance timer circuit that transmits the cylinder deactivation maintenance signal for a predetermined period of time from the time of switching.