JP3102227B2 - Cylinder operation control method for multi-cylinder engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder-stop operation control method for a multi-cylinder engine, and more particularly, to a cylinder-stop operation for preventing a shock caused by an output fluctuation when switching between an all-cylinder operation mode and a cylinder-stop operation mode. It relates to an operation control method.

[0002]

2. Description of the Related Art During a partial load operation such as a steady driving operation or a deceleration driving operation, the fuel supply to some of the cylinders is stopped, and the operation of the valve operating mechanism of the cylinders is stopped to execute an all cylinder operation mode. From the cylinder-stop operation mode to reduce fuel consumption and reduce harmful exhaust gas components.
A cylinder operation control method for a multi-cylinder engine is disclosed in, for example,
-150412.

In the conventional cylinder stop operation control method, a load is detected by an intake pipe pressure (boost pressure) sensor or an air flow sensor, and a threshold value for switching determination using the engine speed as a parameter is set. The switching between the all-cylinder operation mode and the closed-cylinder operation mode is performed by comparing the load with the set load. Comparing the engine torque characteristics with respect to the throttle opening in the cylinder-stop operation mode and the all-cylinder operation mode, higher torque is obtained in the cylinder-stop operation mode in the low throttle opening range, and the cylinder-stop in the high opening range. It is known that the torque in the operation mode is lower than that in the all-cylinder operation mode, and the torque difference between the all-cylinder operation mode and the cylinder-stop operation mode gradually increases as the opening increases. In the high opening range, the shaft torque is required for accelerating operation or the like. Will occur. Therefore, when switching between the all-cylinder operation mode and the closed-cylinder operation mode is performed at a point (cross point) where the engine torque characteristic with respect to the throttle opening in the closed-cylinder operation mode and the all-cylinder operation mode intersects, no torque difference occurs, and the Will not occur. Since such a cross point changes with a change in the engine speed, the above-described switching determination threshold is set using the engine speed as a parameter.

[0004]

However, even if the engine speed is the same, the vehicle speed differs depending on the selected shift speed. If the vehicle speed is different, the running load during steady running will be different. Therefore, when switching between the all-cylinder operation mode and the cylinder-stop operation mode is performed using the switching determination threshold set according to the engine speed, a shock occurs at the time of switching depending on the shift speed, and such a shock is accelerated. There is a problem that if it occurs during the course of deceleration or during deceleration, the driver may feel uncomfortable or feel unpleasant.

In order to solve this problem, a threshold map for setting a mode switching determination threshold value is prepared in advance for each shift speed, and the established shift speed is detected to correspond to the detected shift speed. A method of setting a determination threshold based on a threshold map to be performed has been proposed. However, this method requires a sensor for detecting the gear position. In a vehicle equipped with an automatic transmission, detection of the D range, the second speed, and the first speed range can be performed by a normal shift sensor, but if a special gear position detection sensor is not used,
The third speed and the fourth speed need to be estimated from the engine speed and the vehicle speed. Further, threshold maps are required for the number of gears, and the work of matching these map values requires labor and time. For this reason, there is a problem that the system construction becomes complicated in terms of hardware and software. .

The present invention has been made to solve such a problem, and when switching between the all-cylinder operation mode and the closed cylinder operation mode, the driver does not feel uncomfortable due to the switching shock, and furthermore, It is another object of the present invention to provide a method for controlling the cylinder-stop operation of a multi-cylinder engine that does not require addition of new hardware such as a sensor and a complicated control program.

[0007]

According to the present invention, there is provided, in accordance with the present invention, a method of stopping the supply of fuel to a predetermined cylinder when a predetermined cylinder closing condition is satisfied based on an operating state of a vehicle. At the same time, the operation of the valve operating mechanism of the cylinder is stopped to shift from the all-cylinder operation mode to the closed cylinder operation mode,
In the cylinder-stop operation control method for a multi-cylinder engine, a parameter value related to an actual engine shaft output is detected, a vehicle speed is detected, a determination threshold is set in accordance with the detected vehicle speed, and the determined parameter value is set as the determined parameter value. Switching between the all-cylinder operation mode and the closed cylinder operation mode by comparing a threshold value,
The determination threshold for traveling while maintaining the vehicle speed has detected
The amount of horsepower that should be generated against running load resistance
It is set to a value corresponding to the value.

As the parameters related to the engine shaft output, an intake air amount per unit time of the engine, a throttle opening, and the like are preferable.

[0009]

The present invention detects a parameter value related to the vehicle speed and the shaft output of the engine, for example, the amount of intake air per unit time, and the running load resistance (consumption horsepower) for the vehicle to maintain the current vehicle speed; By determining whether the vehicle is in an accelerating traveling state, a steady traveling state, or a decelerating traveling state, the all-cylinder operation mode is determined at the time of transition from the steady traveling state to the acceleration traveling state or vice versa. And switching the cylinder-stop operation mode, it is based on the knowledge that even if a small switching shock occurs, the occurrence of the shock coincides with the switching point from the steady running to the acceleration running, so that the driver does not feel uncomfortable. is there.

[0010] The running load resistance can be substantially unambiguously estimated based on the vehicle speed even at different speeds, and the discrimination threshold set according to the vehicle speed is determined by the running load at which the vehicle can run while maintaining the vehicle speed. It can be set to a value corresponding to the resistance. Therefore, when the detected parameter value related to the shaft output of the engine exceeds the determination threshold value set in this way, it can be determined that the vehicle is accelerating (requesting output). When it is determined that the vehicle is in the accelerating state, it is operated in the all-cylinder operation mode. When it is determined that the vehicle is not in the accelerating state, but is in the steady driving state or the decelerating driving state, it is operated in the closed cylinder operation mode. Switching between the cylinder operation mode and the cylinder-stop operation mode is performed extremely smoothly without a sense of incongruity.

[0011]

An embodiment of the present invention will be described below with reference to the accompanying drawings. First, an outline of a control device to which the method of the present invention is applied and which controls the fuel supply control and the operation of the valve operating mechanism will be described with reference to FIG. The engine E is, for example, a 6-cylinder gasoline engine (hereinafter, simply referred to as an engine), and a valve mechanism 1 for opening and closing the intake valve 8 and the exhaust valve is disposed in the cylinder head. Details of the valve train 1 will be described later.

An intake passage (intake pipe) 16 is provided on the intake side of the engine E, and an air cleaner 16a is attached to the open end of the engine E on the atmosphere side. A throttle valve 18 is provided in the middle of the intake pipe 16, and a rear end of the intake pipe 16 is connected to a surge tank 16b. In addition, from the surge tank 16b, an intake manifold 16c connected to the intake passage 7a of each cylinder is provided. A boost pressure sensor 28 for detecting an intake passage pressure (boost pressure) Pb is attached to the surge tank 16b, and this sensor 28 is electrically connected to an electronic control unit (ECU) 25 to be described later. The detection signal Pb is supplied to the ECU 25
To supply. Intake passage 7a immediately upstream of each intake valve 8
Injection valves 15 are provided respectively, and each injection valve 15 is
5 is driven to open by a drive signal from the ECU 25 to supply a required amount of fuel to each cylinder.

FIGS. 2 to 5 show details of the above-described valve operating mechanism 1. The valve operating mechanism 1 includes a rocker shaft 2 and a primary rocker arm (hereinafter simply referred to as a "rocker arm").
3, a rocker arm 4, a cam 5, and the like.
The rocker arm 3 has a base end 3a fixed to the rocker shaft 2 and distal ends 3b, 3b having a substantially T-shape divided into two branches, and lash adjusters 6, 6 at the distal ends 3b, 3b.
Is installed. The rocker arm 4 has a base end 4a rotatably supported on one side of the base end 3a of the rocker arm 3 of the rocker shaft 2. Both ends of the rocker shaft 2 are supported by bearings 7 a provided on a cylinder head 7, and the distal ends 3 b of the rocker arm 3 are connected to the stem heads of the intake valves 8 via lash adjusts 6. Is in contact with

The rocker shaft 2 has a piston hole 2a (FIG. 3) diametrically formed in a portion supporting the base end 4a of the rocker arm 4, and one end of the piston hole 2a is formed in the shaft center.
And an oil passage 2b having the other end opened at one end surface. The other end of the oil passage 2b is connected to a hydraulic circuit 20, so that a predetermined hydraulic pressure P is supplied. The hydraulic circuit 20 is controlled by the ECU 25.

The rocker arm 4 has a piston hole 4c formed in the base end 4a in a radial direction corresponding to the piston hole 2a of the rocker shaft 2, and a lid 9 is fitted to the open end thereof in a liquid-tight manner. I have. A roller 10 is rotatably supported at the tip 4b. The roller 10 is in contact with the cam 5 and rotates with the rotation of the cam 5. The base end 4a of the rocker arm 4 is provided with a projection 4d (FIG. 4) on the side opposite to the roller 10, so that the lost motion assembly 1
One tip 11a is pressed.

A piston 12, a spring seat 13, and a spring 14 are housed in a piston hole 2a of the rocker shaft 2. The spring 14 is contracted between the base end of the piston 12 and the spring seat 13, and acts in a direction to push the piston 12 out of the piston hole 2a. The piston 12
When the hydraulic pressure P is not supplied, as shown in FIGS. 3 and 4, the piston 14 is pushed out of the piston hole 2a by the spring force of the spring 14 and its tip is fitted into the piston hole 4c of the rocker arm 4, and the rocker arm 4 and the rocker shaft 2 are connected. Join. Thus, the rocker arm 3 swings together with the rocker arm 4 with the rotation of the cam 5 to drive the intake valves 8.

When the hydraulic pressure P is supplied from the hydraulic circuit 20, the piston 12 receives a spring 14 as shown in FIG.
Is pulled into the piston hole 2a of the rocker shaft 2 against the spring force of the rocker arm 2 and the tip thereof is disengaged from the piston hole 4c of the rocker arm 4 so that the rocker arm 4 and the rocker shaft 2
The bond with is released. As a result, the rocker arm 4
Even when the cam 5 rotates, the cam 5 rotates idly with respect to the rocker shaft 2, and the rocker arm 3 does not drive the intake valves 8, 8 and holds the valve closed. As a result, the cylinder is closed. At this time, the rocker arm 4 is
1, the roller 10 is brought into contact with the cam 5 to prevent the roller 10 from jumping up.

The exhaust-side valve operating mechanism (not shown) has the same structure as the intake-side valve operating mechanism 1. When the cylinder is closed, the operation of the exhaust valve of the cylinder is stopped to maintain the closed state. I do.
The switching control of such a valve operating mechanism is, for example, three cylinders # 1, # 3, and # 5 in the case of a six-cylinder engine (three cylinders in one bank in the case of a V-type engine). 3
When the engine is in the cylinder closed operation mode, the intake and exhaust valves are both stopped from driving and are closed.

The ECU 25 is a central processing unit (CP) for performing fuel injection control and operation control of the valve mechanism 1 in the all-cylinder operation mode and the closed cylinder operation mode of the engine.
U), a storage device such as a ROM or a RAM for storing control procedures (programs), various program variables, coefficient values, etc., an input / output interface for controlling input / output of various detection signals and drive signals, a counter device, etc. It is configured.

On the input side of the ECU 25, in addition to various sensors for detecting the operating state of the engine, for example, the above-described boost pressure sensor 28, a throttle opening sensor 29 for detecting the valve opening (θ) of the throttle valve 18; A crank angle sensor (Ne sensor) 26 for detecting a predetermined crank angle position of each cylinder, a vehicle speed sensor 27 for detecting a vehicle speed V, and an engine coolant temperature (Tw) sensor attached to a cylinder block of the engine E and detecting an engine coolant temperature Tw. An atmospheric pressure sensor or the like for detecting the atmospheric pressure is connected, and each sensor supplies a detection signal to the ECU 25.

Next, the operation of the control device configured as described above will be described with reference to the flowcharts of FIGS. First, a method of calculating the vehicle speed V based on the vehicle speed pulse signal supplied from the vehicle speed sensor 27 will be described. The ECU 25 interrupts and executes the subroutine of FIG. It is determined whether the vehicle speed pulse signal from the vehicle speed sensor 27 is at a high level (Hi). If the result of the determination is negative (No), the subroutine ends without doing anything.
If so, the value of the vehicle speed counter NV is incremented by one, and the routine ends.

Next, the ECU 25 interrupts and executes the subroutine shown in FIG. 7 with a clock signal input at a predetermined cycle from the T2 timer. The clock signal generation cycle of the T2 timer is larger than that of the T1 timer of FIG. EC
U25 converts the counter value NV into a vehicle speed conversion value Vs by the following equation (A1) in step S20. Vs = Kvs × NV (A1) Here, Kvs is a conversion coefficient for converting the counter value NV into a vehicle speed conversion value Vs.

Next, the vehicle speed conversion value Vs is filtered by the following equation (A2) to obtain smooth and stable vehicle speed information V which is not affected by noise or the like (step S22). V (n) = Kav × V (n−1) + (1−Kav) × Vs (A2) where Kav is a smoothing coefficient, and is set to a positive appropriate value smaller than 1. When the calculation of the vehicle speed V is completed, the vehicle speed counter value NV is reset to 0 (step S2).
4), the subroutine ends.

FIG. 8 shows a main routine repeatedly executed by the ECU 25. The ECU 25 first executes step S
In step 30, a boost pressure determination threshold value Pmkt corresponding to the engine speed Ne is read from the cylinder-stop operating region pressure map.
FIG. 9 shows the relationship between the engine speed Ne and the determination threshold Pmkt. In the operating region where the boost pressure (intake pipe pressure) Pb detected by the boost pressure sensor 28 becomes smaller than the boost pressure determination threshold value Pmkt set according to the detected engine speed Ne, the cylinder-stop operation is performed. This shows an area where the engine E has room for output. In other words, the boost pressure determination threshold value Pmkt indicates the output limit of the engine E during the cylinder deactivated operation. If the detected boost pressure Pb is higher than the boost pressure determination threshold value Pmkt, the driver requests a larger engine output. This means that the engine output cannot be obtained in the cylinder-stopped operation mode in spite of the above, and the operation must be performed in the all-cylinder operation mode.

The ECU 25 can execute the cylinder-stop operation mode control in consideration of whether or not the boost pressure Pb detected in step S32 is equal to or less than the boost pressure determination threshold value Pmkt, that is, the engine-side output limit. It is determined whether or not. If the determination result is negative (No), the process proceeds to step S39, in which the cylinder-stop operation is prohibited, and the all-cylinder operation mode control is executed.

In the all-cylinder operation mode control, the ECU 25
The output of the drive signal to the hydraulic circuit 20 (FIGS. 1 and 3) is stopped, the solenoid valve is deenergized, and the oil passage 2 of the rocker shaft 2 is turned off.
The supply of the hydraulic pressure P to b is stopped. At this time, as shown in FIG. 4, the piston 12 protrudes from the piston hole 2a of the rocker shaft 2 by the spring force of the spring 14, the tip is fitted into the piston hole 4c of the rocker arm 4, and the rocker shaft 2 and the rocker arm 4 are connected. ing. When the cam 5 rotates in this state, the rocker arm 4 swings, and the rocker arm 3 swings together with the rocker arm 4 to drive the valve 8. Then, the ECU 25 calculates the valve opening time of the fuel injection valve according to the engine operating state, outputs a drive signal to the fuel injection valve 15 over the calculated valve opening time, and supplies a required amount of fuel to the fuel injection valve. To the engine E.

On the other hand, if the determination result of step S32 is affirmative (Yes), the process proceeds to step S34, and the intake air amount Qair is calculated as a parameter value related to the engine shaft output. The calculation of the intake air amount Qair is based on the boost pressure sensor 2
Pressure (intake pipe pressure) Pb detected by 8
And the engine speed Ne detected by the crank angle sensor 26 is calculated by the following equation (M1).

Qair = Pb × Ne × Kair (M1) where Kair is a conversion coefficient (constant) for converting into an intake air amount. Next, the ECU 25 proceeds to step S36, and reads an intake air amount determination threshold value Qcr corresponding to the vehicle speed V from the cylinder-inactive region intake air amount map. FIG. 10 shows the relationship between the vehicle speed V and the determination threshold value Qcr. The setting of the determination threshold value Qcr is set only by the vehicle speed V without being related to the gear position or the like.

Qcr = g (V) (M2) The intake air amount determination threshold value Qcr set in accordance with the vehicle speed V is substantially the same as the intake air amount necessary for running the vehicle at the vehicle speed V at a constant speed. Is set, and the discrimination threshold Qcr set in this way is set.
Therefore, in the region where the intake air amount Qair calculated by the above equation (M1) is small, the engine shaft output corresponding to the intake air amount Qair cannot overcome the traveling load resistance, and the constant speed traveling state cannot be maintained. The operation area is shown. In this region, the driver intends to perform deceleration operation, and may operate in the cylinder-stop operation mode. Conversely, a region where the intake air amount Qair is larger than the determination threshold value Qcr can be determined to be a region where the driver intends to accelerate.

In step S36, it is determined whether or not the calculated intake air amount Qair is equal to or smaller than a determination threshold value Qcr.
If the determination result is negative (No), the aforementioned step S
Proceed to 39 to prohibit control in the cylinder-stop operation mode. On the other hand, if the decision result in the step S36 is affirmative (Yes), the process proceeds to a step S38, in which the control in the cylinder-stop operation mode is permitted, and the routine ends.

As described above, when the control in the cylinder-stop operation mode is permitted in step S38 and the operation mode shifts from the all-cylinder operation mode to the cylinder-stop operation mode, the ECU 25 outputs a drive signal to the hydraulic circuit 20 to output the electromagnetic signal to the electromagnetic circuit 20. The valve is urged to supply the oil pressure P to the oil passage 2b of the rocker shaft 2 to release the connection between the rocker arm 3 and the rocker arm 4 and cut off the fuel supplied to the fuel injection valve 15.

In the above embodiment, the intake air amount Q to the engine E is used as a parameter related to the engine shaft output.
Although air is used, the parameters related to the output of the engine shaft are not limited to these, and the throttle valve opening, accelerator pedal depression, intake pipe pressure, and the like can be used. Further, the valve operating mechanism for realizing the cylinder-stop operation is not limited to the one in the above-described embodiment, and can switch between the cylinder-stop operation mode and the all-cylinder operation mode, and also switch the valve lift and the valve opening timing. Possible valve operating mechanism (for example, see JP-A-56-15123)
No. 0) and the valve train disclosed in Japanese Patent Application Laid-Open No. 63-167016 are also applicable to the method of the present invention.

[0033]

As is apparent from the above description, according to the method for controlling the cylinder deactivation operation of the multi-cylinder engine of the present invention, the parameter value related to the actual engine shaft output is detected, and the vehicle speed is detected. set the determination threshold value corresponding to the detected vehicle speed is compared with the determination threshold set between the detected parameter value after switching between all cylinder operation mode and the cylinder deactivation operation mode, the determine specific threshold, it detects the vehicle speed for traveling to maintain, since so as to set to a value corresponding to the magnitude of the consumption horsepower to be generated against the running load resistor, rest at a timing to shift to the acceleration running operation from the constant-speed driving operation It is possible to switch from the cylinder operation mode to the all-cylinder operation mode. Even if a slight switching shock occurs during this switching, the driver does not feel uncomfortable due to the shock. Further, the control method of the present invention does not need to detect the shift speed, so that it can be applied to both manual transmission vehicles and automatic transmission vehicles. Further, there is an advantage that stable acceleration determination can be performed even in an operation state in which the change in the throttle valve opening is small, such as during slow acceleration.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which a method for controlling a cylinder closed operation of a multi-cylinder engine according to the present invention is applied.

FIG. 2 is a perspective view of an essential part showing one embodiment of a valve train for carrying out the method of the present invention.

FIG. 3 is a sectional view taken along the line AA of FIG. 2;

FIG. 4 is a partial cross-sectional view showing an operation state of the valve train of FIG. 2 in an all-cylinder operation mode.

FIG. 5 is a cross-sectional view of a main part showing an operating state of the valve operating mechanism of FIG. 2 in a pause operation mode.

FIG. 6 shows a vehicle speed sensor 27 to an electronic control unit (ECU) 2
5 is a flowchart illustrating a procedure for counting pulse signals input to a counter 5;

7 is a flowchart showing a procedure for calculating a vehicle speed V based on a vehicle speed pulse counted out in the subroutine shown in FIG. 6;

FIG. 8 is a flowchart illustrating a procedure for determining whether or not execution of a cylinder-stop operation mode is permitted;

FIG. 9 shows the engine speed Ne and the boost pressure determination threshold value Pmk.
6 is a graph showing a relationship with t.

FIG. 10 is a graph showing a relationship between a vehicle speed V and a suction amount determination threshold value Qcr.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve operating mechanism 8 Intake valve 12 Intake passage 15 Fuel injection valve 20 Hydraulic circuit 25 Electronic control unit (ECU) 26 Crank angle sensor 27 Vehicle speed sensor 28 Boost pressure sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-198337 (JP, A) JP-A-57-195835 (JP, A) JP-A-57-198336 (JP, A) JP-A-56-198336 29034 (JP, A) JP-A-60-138234 (JP, A) JP-A-60-138235 (JP, A) JP-A-60-138236 (JP, A) JP-A-60-138237 (JP, A) 63-171636 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 13/00-45/00 F01L 13/00 302

Claims (1)

(57) [Claims] When a predetermined cylinder closing condition is established based on an operation state of a vehicle, fuel supply to a predetermined cylinder is stopped, and operation of a valve operating mechanism of the cylinder is stopped to change from a full cylinder operation mode. In the cylinder-stop operation control method of the multi-cylinder engine to shift to the cylinder-stop operation mode, a parameter value related to an actual engine shaft output is detected, a vehicle speed is detected, and a determination threshold value according to the detected vehicle speed is set. Switching between the all-cylinder operation mode and the closed-cylinder operation mode is performed by comparing the detected parameter value with a set discrimination threshold, and the discrimination threshold is set so that the traveling load is maintained to maintain the detected vehicle speed. Should occur against resistance
A method for controlling the cylinder-stop operation of a multi-cylinder engine, which is set to a value corresponding to the magnitude of the consumed horsepower .