JP2697520B2 - Automotive engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile engine and, more particularly, to a vehicle engine having a structure capable of suspending operation of a valve device for intake and exhaust in a selected one of a plurality of cylinders. Automobile engine.

[0002]

2. Description of the Related Art Generally, in an automobile engine,
The maximum opening amount of the valve corresponds to the maximum lift amount from the cam profile of the valve opening / closing cam, and since this amount is always constant, the load from the engine speed and the throttle opening is not affected. At present, it is not possible to set an appropriate intake / exhaust efficiency. That is, for example, in the case of an engine that requires high-speed rotation, the above-described cam profile is set in consideration of increasing the intake ratio and the exhaust efficiency of the air-fuel mixture. Fuel consumption rate tends to be sacrificed. On the other hand, when the cam profile is set in consideration of the fuel consumption rate, the output may not be sufficiently obtained at the time of high-speed rotation or high-load operation.

In order to satisfy such operating conditions of the engine, it is necessary to satisfy both of the reduction of fuel consumption at low speed and low load operation and the securing of output at high speed and high load operation. A cam with a cam profile for low speed and high speed is prepared as a valve opening / closing cam, and a rocker arm provided with a cam follower that is in abutting contact with each of the cams, and a swing fulcrum of the arm is formed. The rocker shaft is separated from the rocker shaft, and the rocker shaft is integrally provided with a sub rocker arm that is in contact with the valve stem. And the uncoupled position are selected, and the swing of the rocker arm on the connected side is Structure as to transmit open and close control of the valve has been proposed in Kkaamu
(For example, Japanese Patent Application No. 2-18, which was filed earlier by the present applicant.
No. 2131). In this structure, in addition to switching the valve opening / closing amount by the valve opening / closing cam at the time of low-speed operation and high-speed operation, the connection of the plunger to each rocker arm is not performed, and so-called valve closing on the cylinder side is performed. It is also possible to stop the operation and close the cylinder.

In the above-described cylinder rest state, for example, in the case of a four-cylinder engine, the first cylinder and the fourth cylinder having the same piston operation stroke correspond to each other to reduce the fuel consumption. This cylinder rest setting is executed by a map determined by determining the volumetric efficiency of air in the cylinder corresponding to the engine speed and the load information.

[0005]

By the way, in an engine using such a cylinder-stop system, for example, when the engine is switched from the all-cylinder state to the cylinder-stop state during idling operation in which the rotation of the engine tends to become unstable. In, the rotation speed in the cylinder rest state is set higher than that in the case of all cylinders, so that stability on the vibration surface and a sharp drop in rotation are prevented. As the above-mentioned idle speed, for example, the full cylinder state is set to 750 rpm, and the idle cylinder state is set to 850 rpm. For this reason, in the engine using the cylinder-stop system, when switching from the all-cylinder state to the cylinder-stop state during idle operation, the opening and closing valve of the idle speed control mechanism is temporarily opened and the air /
After the air amount is increased via the control valve and the rotation is increased, the cylinder is switched to the cylinder-stop state.

On the other hand, when the air amount is increased at the time of switching to the cylinder rest state, the air is increased in order to prevent the output from becoming abnormally large in the explosion stroke by the normal ignition timing setting. The ignition timing is retarded in accordance with the amount to prevent the occurrence of torque shock in the transitional period at the time of switching (for example, Japanese Patent Application No. 3-346709, which is a prior application of the present applicant). ).

However, in such a structure for correcting the ignition timing, even if an attempt is made to avoid a drop in rotation by increasing the amount of air at the time of switching from the all-cylinder state to the closed-cylinder state, the number of rotations due to the increased amount of air is reduced. The retard of the ignition timing is executed in response to the increase in the ignition timing. Therefore, there is a possibility that the number of revolutions at the time of switching to the cylinder rest state decreases, and the idle rotation becomes unstable with the decrease in output.

In view of the above, an object of the present invention is to solve the above-described problems in an automobile engine using the cylinder deactivation system.
An object of the present invention is to provide an automobile engine having a structure capable of preventing an extremely low idle rotation from occurring when the cylinder is switched from the all-cylinder state to the closed cylinder state during idling.

[0009]

SUMMARY OF THE INVENTION In order to achieve this object, the present invention comprises a valve opening / closing cam provided with a cam profile for low speed and high speed, and switches a driven state of the cam on the rocker arm side. Thus, in an automobile engine equipped with a valve mechanism capable of setting a valve opening / closing amount and a valve rest state, a rotational speed sensor for detecting an engine rotational speed, and a volumetric efficiency of air in a cylinder according to a throttle opening. Pressure sensor, an idle speed control mechanism, an ignition timing setting device, a crank angle sensor, the rotation speed sensor, the boost pressure sensor and the crank angle sensor are connected to the input side, and the output side A drive unit of the valve mechanism,
A control unit to which the drive unit of the idle speed control mechanism and the ignition timing setting device are connected, wherein the control unit operates the valve of all cylinders based on load information based on the engine speed and the volumetric efficiency of air. A map is provided for setting the all-cylinder state to be opened and closed and the closed cylinder state by stopping the opening and closing of some valves of all the cylinders. At the time of switching, the idle speed control mechanism issues a command to increase the amount of air, and also issues a command to prohibit retard correction of the ignition timing executed in accordance with the increase, and then switches to the cylinder stopped state. I have.

[0010]

According to the present invention, when switching from the all-cylinder state to the closed-cylinder state, an increase in the amount of air by the idle speed control mechanism is set, while an increase in the output torque due to the increase in the amount of air is suppressed. By performing the switching to the cylinder stop state after prohibiting the retard correction of the ignition timing to be performed for performing the operation, it is possible to prevent an abnormal decrease in the rotation speed at the time of switching to the cylinder stop state.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to FIGS.

FIG. 1 is a system configuration diagram of an automobile engine according to an embodiment of the present invention. In FIG. 1, an intake / exhaust port of an engine 1 is provided with a valve mechanism 2 described in the above specification. The hydraulic drive unit of the valve mechanism 2 is set to a working position by a control unit, which will be described later, and is operated to open and close the valve in all the cylinders and open and close the valve only in some of the cylinders. An operation for suspending the opening and closing of the valve in the cylinder is performed. On the other hand, a control unit (indicated by an indication "ECU" in the figure) 3 is constituted by a microcomputer for comprehensively performing various controls related to engine combustion such as setting of a fuel injection amount. The input side via an interface (not shown) is a rotation speed sensor 4 for detecting the engine rotation speed, and a boost pressure sensor for detecting the boost pressure located upstream of the intake port, as related to the present embodiment. 5, a crank angle sensor 6 is connected, and a hydraulic drive of the valve mechanism 2, a drive of the idle speed control mechanism 7, and a distributor 8 as an ignition timing setting device are connected to the output side. I have.

In the control unit 3, based on the water temperature, the engine speed 4 and the volumetric efficiency of the air obtained by the boost pressure sensor 5, the state of all cylinders / closed cylinders according to the load is determined from the map shown in FIG. Although not shown, the torque correction map described in the above specification suppresses a decrease in output torque when switching from the all-cylinder state to the closed-cylinder state during traveling. ing. This torque correction map is applied when the operation mode is switched from the all-cylinder state to the closed-cylinder state, and the air amount is once increased to increase the rotation speed. The retard amount of the ignition timing is set according to the increase in the number.

When the condition for switching from the all-cylinder state to the closed-cylinder state during idle operation is satisfied, the control unit 3 increases the air amount in the idle speed control mechanism 7 as shown in FIG. On the other hand, the ignition timing is corrected based on the increase in the air amount. In this case, the retard is prohibited. This is executed in order to suppress a decrease in the output during the explosion stroke due to the retard of the ignition timing and to easily increase the rotation speed. The ignition timing correction prohibition period is a period until the increase of the air in the idle speed control mechanism 7 ends, in other words, a period until the idle rotation speed at the time of cylinder deactivation is obtained. I have.

Since the present embodiment is configured as described above,
Now, the operation will be described with reference to a flowchart showing the operation of the control unit, as shown in FIG. That is, it is determined whether or not the engine is idling (ST1), and if it is the idle operation, it is determined whether or not all cylinders are in operation.
(ST2). And, in the case of the all cylinder state, the cylinder closing condition,
That is, it is determined whether or not the condition for switching to the cylinder-stop state based on the relationship shown in FIG. 2 is satisfied (ST3). If so, the opening degree of the on-off valve is increased with respect to the idle speed control mechanism 7. Then, a command to increase the air amount is output, and a command to prohibit the correction of the ignition timing is output to the distributor 8 in accordance with the increase in the opening of the on-off valve (ST4). Therefore, in the cylinder executing the combustion stroke, the explosion stroke with the air amount increased at all times is performed by the same ignition timing as in the normal operation, and the output increases rapidly, so that the rotation speed also increases. Will be.

On the other hand, the control unit 3 detects an increase in the number of revolutions due to an increase in the amount of air and prohibition of correction of the slight ignition timing, and determines whether or not the number of revolutions has reached or exceeded the cylinder-stop switching determination revolution number (A). Then, a signal is output to the hydraulic drive unit of the valve mechanism 2 (ST6) to switch the cylinders off when the rotation speed is equal to or higher than the rotation speed (ST5). As described above, when it is determined that a decrease in the number of revolutions is not expected when the cylinder is switched to the closed cylinder state, the opening degree of the on-off valve in the idle speed control mechanism 7 is changed from the air amount increasing state to the normal operation state. In order to match, it is returned to the decreasing tendency (ST7), and further, the ignition timing correction prohibition is released (ST8). Therefore, the distributor 8 adjusts the ignition timing based on the signal from the crank angle sensor 7 input to the control unit 3.

[0017]

As described above, according to the present invention, when switching from the all-cylinder state to the closed-cylinder state during idling operation, the intake air amount is increased to increase the rotational speed, and the rotational speed is increased. Since the ignition timing correction executed to suppress the torque shock due to the above is prohibited and the increase in the rotation speed is promoted and the switching to the cylinder stop state is executed, at the time when the cylinder is switched to the cylinder stop state, It is possible to prevent a sharp drop in the idle speed of the engine.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a system configuration of an automobile engine according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining an all-cylinder / rest-cylinder determination map in a control unit used in the system configuration shown in FIG. 1;

FIG. 3 is a graph showing a relationship between all cylinders / rest cylinders, a change in boost pressure, a change in torque, and an ignition timing adjustment for explaining a control method executed by a control unit in the system configuration shown in FIG. 1; FIG.

FIG. 4 is a flowchart for explaining the operation of a control unit in the system configuration shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Valve mechanism 3 Control part 4 Speed sensor 5 Boost pressure sensor 7 Idle speed control mechanism 8 Distributor

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location F02D 41/08 310 F02D 41/08 310 43/00 301 43/00 301B 301K

Claims (1)

(57) [Claims] 1. A valve opening / closing cam having a low-speed and high-speed cam profile set therein, and a driven state of the cam on the rocker arm side is switched.
For an automobile engine equipped with a valve mechanism that can set the opening and closing amount of the valve and the rest state of the valve, to determine the rotation speed sensor that detects the engine rotation speed and to determine the volumetric efficiency of air in the cylinder according to the throttle opening A boost pressure sensor, an idle speed control mechanism, an ignition timing setting device, a crank angle sensor, the rotation speed sensor, the boost pressure sensor, and the crank angle sensor connected to an input side, and an output side connected to the valve mechanism. A drive unit, a drive unit of the idle speed control mechanism, and a control unit to which the ignition timing setting device is connected.The control unit controls all cylinders based on load information based on engine speed and volumetric efficiency of air. The state of all cylinders that open and close valves as targets and the opening of some valves in all cylinders A map is provided for setting the closed cylinder state by closing and closing. When switching from the all cylinder state selected by the map to the closed cylinder state during idling operation, the idle speed control mechanism issues an air increase command, An engine for an automobile, characterized in that a command is issued to prohibit retard correction of the ignition timing executed in accordance with an increase in the amount of fuel, and then the cylinder is switched to a cylinder-stop state.