JPH07233717A - Engine controller - Google Patents

Abstract

PURPOSE:To perform ignition control by ignition timing which is suited for a cam in actual use during the switching control time of the cam. CONSTITUTION:The rate of change of an engine intake air quantity is monitored after outputting a command for switching from a cam for low speed to the cam for high speed or vice versa (S3, S6). The point of time when the engine intake air quantity shows more than the predetermined rate of change after outputting the switching command (S4, S7) is discriminated as to timing when the cam is actually switched, and the switching control of an ignition timing map is carried out by this timing (S5, S8).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device, and more particularly, in an engine in which valve opening characteristics are switched according to operating conditions, switching of engine control characteristics corresponding to switching of the valve opening characteristics is actually performed. The present invention relates to a technique for synchronizing with the switching of the valve opening characteristic of.

[0002]

2. Description of the Related Art Conventionally, the lift characteristic (opening characteristic) of an intake valve or an exhaust valve is changed to, for example, a high-speed cam for the purpose of achieving both high torque characteristics at low and medium speed operation and improved output at high speed operation. It is known that the low-speed cam and the low-speed cam are used differently depending on operating conditions, and thereby the intake / exhaust timing or the intake / exhaust amount is controlled (Japanese Patent Laid-Open Nos. 63-167016 and 63/63). -5780
5 and JP-A-5-171909).

[0003]

By the way, when the high-speed cam and the low-speed cam are selectively used as described above, if there is a difference in the required ignition timing characteristics depending on the cams used, the cam state and the ignition timing characteristics are incompatible. As a result, phenomena such as hesitation and knocking that impair drivability occur. Therefore,
In the above case, a plurality of ignition timing maps corresponding to the required ignition timings for each cam are provided in advance, and it is required to switch and use the ignition timing maps according to the switching of the cams.

However, the above-mentioned Japanese Patent Laid-Open No. 63-1670.
16, JP-A-63-57805, JP-A-5
In the system for switching the valve opening characteristic by controlling the hydraulic pressure as disclosed in Japanese Patent Application Laid-Open No. 171909, etc., after the switching command is output based on the operating condition (after the opening / closing of the hydraulic control solenoid valve is controlled, ) Before the valve opening characteristic (cam) is actually switched, an operation delay time occurs due to a delay in the response of the solenoid or a delay in the change in hydraulic pressure (see Fig. 8: switching control between high-speed cam and low-speed cam). ).

Therefore, if the ignition timing map is switched in synchronization with the switching command, the ignition timing map is switched before the valve opening characteristic is actually switched, and the valve opening characteristic is actually switched from the switching command. Since the ignition timing becomes unsuitable before the switching, troubles such as hesitation and knocking occur.

Even if the operation delay time is preset as a fixed constant and the ignition timing map is switched when a certain operation delay time elapses from the switching command, the operation delay time is also changed. Is the temperature of the hydraulic oil in the switching mechanism and the variation of each engine,
Furthermore, since it fluctuates due to changes over time of the variable valve mechanism, it is difficult to stably switch the ignition timing map at the optimum timing (at which the valve opening characteristic is actually switched).

The engine control parameter whose required characteristic changes due to the switching of the cam is not limited to the ignition timing. For example, the required operation characteristic such as the control operation amount when performing the air-fuel ratio feedback control also changes depending on the cam used. Even in this case, if the switching of the control operation amount is not accurately synchronized with the actual switching of the valve opening characteristics, the desired control cannot be executed and the operability of the engine is adversely affected. turn into.

The present invention has been made in view of the above problems, and in an engine in which the valve opening characteristics are switched and controlled according to operating conditions, switching of the engine control characteristics corresponding to each valve opening characteristic is performed by an actual valve. It is an object of the present invention to be performed in synchronization with switching of the open characteristic with high accuracy.

[0009]

Therefore, an engine control device according to the invention of claim 1 is constructed as shown in FIG. In FIG. 1, the valve opening characteristic switching means is
The switching command output means is a means for switching the valve opening characteristic of the engine to a plurality of preset values, and the switching command output means outputs a switching command of the valve opening characteristic to the valve opening characteristic switching means according to the operating conditions.

On the other hand, the switching timing determination means is the timing at which the valve opening characteristic is actually switched at the time when the intake air amount of the engine detected by the intake air amount detection means after the switching command shows a change rate of a predetermined value or more. Is determined as. The engine control value switching means switches the engine control value set in advance for each valve opening characteristic based on the switching timing determined by the switching timing determination means.

In the engine control device according to the second aspect of the present invention, the switching timing determination means sets a reference change rate of the intake air amount according to the valve opening characteristics before and after the change, and the reference change rate. And the rate of change of the intake air amount detected by the intake air amount detecting means are compared to determine the timing at which the valve opening characteristic is actually switched.

Further, in the engine control device according to the invention of claim 3, the engine control value switching means switches the ignition timing preset for each valve opening characteristic as the engine control value.

[0013]

In the engine control device according to the first aspect of the present invention, the valve opening characteristic is switched based on the switching command output according to the operating condition. The engine control set for each valve opening characteristic is performed. The value switching is not performed in synchronization with the switching command, but is performed when the engine intake air amount changes more than a predetermined amount after the switching command.

That is, in general, when the valve opening characteristic is switched, the same throttle valve opening,
The intake air amount changes even under the condition of the rotation speed. Therefore, if the switching of the actual valve opening characteristic is delayed with respect to the output of the switching command, a change in the engine intake air amount due to a change in the charging efficiency will occur after the switching command.

Therefore, the change in the engine intake air amount after the switching command is monitored, and when the intake air amount changes more than a predetermined value, it is considered that the change in the air amount is caused by the actual switching of the valve opening characteristic. The engine control value is switched at the timing when such a change in the air amount is detected. Here, the characteristic of the change in the intake air amount that occurs with the switching of the valve opening characteristic differs depending on the valve opening characteristic before and after the switching. Therefore, in the device according to the invention of claim 2, In determining the switching based on the change in the intake air amount, the reference change rate is set according to the valve opening characteristics before and after the switching, and the accuracy of determining the switching timing based on the change in the intake air amount is improved.

Further, in the apparatus according to the invention of claim 3,
The ignition timing is switched in synchronization with the actual switching of the valve opening characteristics, using the engine control value that is switched when a change in the intake air amount is detected after the switching command as the ignition timing. Ignition control can be ensured even when switching the valve opening characteristics.

[0017]

EXAMPLES Examples of the present invention will be described below. FIG. 2 is a block diagram showing the outline of the system configuration of this embodiment.
In FIG. 2, an engine (not shown) is provided with a variable valve mechanism 101 (valve opening characteristic switching means) that selectively switches the valve opening characteristic (lift characteristic) among a plurality of preset types.

The variable valve mechanism 101 is a hydraulic cam switching mechanism for switching cams as will be described later by operating hydraulic pressure, and the supply of the operating hydraulic pressure is drive-controlled by a control unit 102 as switching command output means. It is configured to be adjusted by the switching valve 103 (hydraulic control valve). The control unit 102 incorporating a microcomputer inputs detection signals from a rotation speed sensor 104 for detecting an engine rotation speed Ne, an air flow meter 105 (intake air amount detecting means) for detecting an intake air amount Qa of the engine, and the like. The valve opening characteristic (used cam) is determined based on these detection signals (operating conditions), and a switching command (open / close) is issued to the switching valve 103 to switch to the valve opening characteristic (cam) corresponding to the determination. Control signal).

Further, since the proper ignition timing changes according to the change of the charging efficiency due to the valve opening characteristic, the control unit 102 has an ignition timing map for each valve opening characteristic in advance, and can switch the valve opening characteristic. Accordingly, the ignition timing map is switched and set (engine control value switching means), the ignition timing (engine control value) is determined based on the selected ignition timing map, and the ignition signal is output to the ignition device 106.

As the ignition timing map, a map in which the ignition advance value is stored for each operating region divided by the engine load and the engine rotation speed Ne is used. The ignition device 106 is composed of an ignition plug, an ignition coil, a power transistor and the like. Here, FIG.
6 shows a specific example of the variable valve mechanism 101.

Explaining this, each cylinder is provided with a single rocker arm 1 corresponding to two intake valves V. The base end of the rocker arm 1 is swingably supported by the cylinder head through a hollow main rocker shaft 3 common to each cylinder, and the bifurcated ends of the rocker arm 1 abut the stem top of the intake valve V. . The rocker arm 1 is formed in a substantially bifurcated shape in a plan view, and the rocker arm 1 is provided with a single free cam follower 2 approximately above the center thereof. Further, in FIG. 4, rollers 11, 11 with which the low speed cams 21, 21 come into contact are provided on both sides of the free cam follower 2.

The base end of the free cam follower 2 is swingably (relatively rotatable) supported by the rocker arm 1 via a sub-rocker shaft 16. The free cam follower 2 does not have a portion that comes into contact with the intake valve V, and a cam follower portion 2A that slidably contacts the high speed cam 22 is formed at the tip of the free cam follower 2 so as to project in an arc shape. In addition, a recess 27 into which a spring retainer 29 is slidably fitted is provided below the free cam follower 2.
The base end of the spring retainer 29 is brought into contact with the rocker shaft 3 by the elastic biasing force of the coil spring 26 supported by the bottom surface of the recess 27.

Further, in the above-described free cam follower 2, a stepped portion 2B with which a later-described lever member 7 is engaged and an inclined portion 2C continuous with this are formed below the cam follower portion 2A. Further, below the rocker arm 1, there is provided a lever member 7 which is swingably supported by a pin 6 on the side of the rocker shaft 3. A protrusion 7A is integrally formed on the upper side of the lever member 7, and a return spring 9 and a spring retainer 10 housed in a recess 8 formed in the rocker arm 1 are used to engage the free cam follower 2 described above. It is urged to be released.

On the other hand, the lower end of the lever member 7 is in contact with the operating plunger 31 driven by the supply of operating hydraulic pressure to the hydraulic chamber 34 provided in the rocker arm 1.
An oil passage for guiding the working oil pressure to the oil pressure chamber 34 is provided through the insides of the rocker arm 1 and the main rocker shaft 3. The rocker arm 1 is formed with a through hole 41 having one end opened to the hydraulic chamber 34 and the other end penetrating the bearing surface for the main rocker shaft 3. An oil gallery 42 is axially formed inside the main rocker shaft 3, and the oil gallery 42 communicates with a through hole 41 of the rocker arm 1 through a through hole 43.

A discharge hydraulic pressure of an oil pump (not shown) driven by the engine is selectively introduced into the oil gallery 42 via a switching valve 103 whose operation is controlled by the control unit 102. Low speed cam 2
1, 21 and the high speed cam 22 between them are integrally formed on a common cam shaft 20, and satisfy the valve lift characteristics (open characteristics) required at low engine speed and high engine speed. Are formed in different shapes.
That is, the high speed cam 22 has a cam profile that makes at least one of the valve lift amount and the valve open period larger than the low speed cam 21. In this embodiment, the valve lift amount and the opening period are both increased, and the valve opening characteristic can be switched between two types by properly using the high speed cam 22 and the low speed cam 21. There is.

According to the variable valve mechanism 101 having the above structure,
In a state where the hydraulic pressure is not supplied to the hydraulic chamber 34 (the hydraulic relief state by the switching valve 103), the rocker arm 1 swings according to the cam profile of the low speed cam 21 to open / close each intake valve V. At this time, the free cam follower 2
Is swung by the high speed cam 22, but the spring 9
The lever member 7 is in the position shown by the solid line in FIG. Therefore, even if there is an input from the free cam follower 2, only the spring 26 bends and the movement of the rocker arm 1 is not affected.

On the other hand, when the working hydraulic pressure is supplied to the hydraulic chamber 34, the working plunger 31 swings the lever member 7 against the return spring 9 and returns it to the position shown by the broken line in FIG. . In this state, the end portion of the lever member 7 engages with the step portion 2B of the free cam follower 2 so that the rocker arm 1 and the cam follower 2 are connected and integrated, and swing about the main rocker shaft 3. become.

Since the high speed cam 22 is formed so that both the valve opening angle and the valve lift amount are larger than the low speed cam 21, the free cam follower 2 is integrated with the rocker arm 1. Rocker arm 1 when rocking
Roller 11 floats up from low speed cam 21, and each intake valve V is driven to open and close according to the profile of high speed cam 22, so that both the opening angle and the lift amount increase.

On the other hand, switching from the high speed cam 22 to the low speed cam 21 lowers the hydraulic pressure introduced into the hydraulic chamber 34 by the control of the switching valve 103, and the elastic restoring force of the return spring 9 causes the lever member 7 and the actuating plunger. This is performed by moving 31 to the original position (the position indicated by the solid line in FIG. 5) and releasing the lock of the rocker arm 1. In this way, the switching valve
By selectively supplying the hydraulic pressure to the hydraulic chamber 34 by the 103, the valve opening characteristic that conforms to the profile of the low speed cam 22 in the low speed range and the opening characteristic of the high speed cam 21 that is higher than that of the low speed cam 22 are provided. Either the angle or the valve opening characteristic suitable for the high speed range where the lift amount is large can be switched and selected.

In this embodiment, the valve opening characteristic switching means is composed of the rocker arm 1, the free cam follower 2, the lever member 7, the plunger 31, the hydraulic chamber 34, the switching valve 103 and the like. In the present embodiment, switching between the high speed cam 21 and the low speed cam 22 is performed depending on whether or not the rocker arm 1 and the cam follower 2 are connected by swinging the lever member 7 as described above. However, the cam switching mechanism is not limited to the above configuration.

For example, as disclosed in JP-A-63-167016 and JP-A-63-57805, a high speed rocker arm and a low speed rocker arm are fitted in a direction parallel to the rocker shaft. A configuration may be adopted in which the high speed cam and the low speed cam are switched by selectively connecting and disconnecting the hole and the plunger.

Further, instead of using a plurality of cams separately, it is possible to mount a cam sprocket capable of controlling the cam phase with a constant operating angle on the cam shaft and switch the intake valve opening / closing timing to an appropriate timing for each speed range. Variable valve timing controller ("New model vehicle manual (FGY32-
1) ", pages B-44 to B-45, edited and published by Nissan Motor Co., Ltd., published in August 1991, etc.), and does not limit the configuration of the variable valve mechanism 101.

Further, although two types of cams, one for high speed and the other for low speed, are provided and these are switched and used, three or more types of cams may be selectively used according to operating conditions. Here, the switching control of the valve opening characteristic (high speed cam and low speed cam) performed by the control unit 102 via the switching valve 103 and the ignition timing setting control associated with the switching control will be described with reference to FIG. It will be described in accordance with the flowchart of.

In this embodiment, the control unit 102 is provided with the functions of the switching timing discriminating means and the engine control value switching means by software as shown in the flow chart of FIG. In the flowchart of FIG. 7, first, at step 1 (denoted as S1 in the figure. The same applies hereinafter), it is determined whether or not a cam switching control permission condition is satisfied. For example, it is preferable that the permission condition is that the temperature of the hydraulic oil is equal to or higher than a predetermined temperature, or that a predetermined low speed operation region is experienced, and a sensor that directly detects the hydraulic oil temperature may be provided. Alternatively, it may be estimated from the cooling water temperature or the like.

If the permission condition is satisfied, the routine proceeds to step 2, where it is judged whether or not the driving condition is to use the high speed cam 22. For example, it is preferable to set that the engine speed Ne is equal to or higher than a predetermined speed as an operating condition using the high speed cam 22, but in addition to this, the operating condition of the high speed cam 22 is determined based on the absolute level of the cylinder intake air amount. However, the detection of the operating condition for switching the cam is not limited.

If it is determined in step 2 that the operating condition is that the high speed cam 22 is used, the process proceeds to step 3 to output a switching command to the high speed cam 22 to the switching valve 103. Then, in the next step 4, the high speed cam 22
After the switching command to output, the air flow meter
Change rate DQ of engine intake air amount Qa detected at 105
It is determined whether or not A (← the latest sampled intake air amount Qa−the sampled intake air amount Qa at the sampling timing before the predetermined time) has become equal to or higher than the reference change rate HQASL.

The reference rate of change HQASL is a low speed cam.
It is a preset value corresponding to the change in the intake air amount (change in the increasing direction) that occurs when switching from 21 to the high-speed cam 22, and the reference value is set after the switching command to the high-speed cam 22 is output. Until the change of the intake air amount exceeding the rate of change HQASL occurs, it is considered that the low speed cam 21 is still used due to the operation delay of the switching valve 103 and the response delay of the change of the operating oil pressure, and the ignition timing. The determination in step 4 is repeated without switching the map.

When a sudden increase in the intake air amount exceeding the reference change rate HQASL occurs after the switching command, the cam is actually switched from the low speed cam 21 to the high speed cam 22 at that time. Estimate and proceed to step 5 at this actual cam switching timing, and use the reference map for ignition timing control as the cam for low speeds up to that point.
21 ignition timing map (low speed ignition timing map)
To the ignition timing map (high-speed ignition timing map) suitable for the high-speed cam 22.

That is, the intake air amount Qa changes stepwise as the charging efficiency (intake efficiency) changes due to switching from the low speed cam 21 to the high speed cam 22. It is determined that the time when the air amount Qa shows a sudden change is the timing when the actual cam switching is performed and the change of the charging efficiency occurs, and the ignition timing map is switched at the timing, and the actual ignition timing map is changed. Step 9 with ignition timing that matches the cam being used
Ignition control is performed.

Similarly, at the time of switching from the high speed cam 22 to the low speed cam 21 (step 6), a reference change rate LQASL (minus indicating a decrease change in the air amount is set in advance corresponding to the change). Value) is the actual rate of change DQ
Until it is determined that A is below (step 7), in other words, until it is detected that the intake air amount has decreased at a predetermined rate or more, it is actually switched to the low speed cam 21. It is determined that the high speed ignition timing map is continuously used after the switching command is output.

On the other hand, when a change in the amount of intake air exceeding the reference change rate LQASL is detected,
It is determined that the low-speed cam 21 has actually been switched, and the low-speed ignition timing map is switched (step 8) at the timing of occurrence of such a change in the intake air amount. As described above, in the present embodiment, the actual switching timing is determined by utilizing the characteristic that the intake air amount changes due to the change in the charging efficiency when the cam is actually switched. Even if the switching is delayed and the delay time fluctuates, it is possible to reliably switch to the required control characteristic for each cam at the actual cam switching timing.

Here, instead of comparing the absolute value of the change rate with the fixed reference value, the reference change rates HQASL and LQASL that differ depending on the switching direction are set, and the charging efficiency (suction efficiency) due to the actual cam switching is set. Since the change is captured, it is possible to determine the actual switching timing with high accuracy regardless of the switching direction.

Further, since the actual cam switching is discriminated based on the change in the intake air amount and the ignition timing map is switched as described above, the ignition control is performed with respect to the required ignition timing of the actually used cam. It is possible to avoid the occurrence of knocking or hesitation due to the non-conformity of the ignition timing at, and it is possible to improve the drivability of the engine at the time of switching the cam.

In the above embodiment, the ignition timing is shown as the engine control value which is changed in accordance with the cam switching. However, in addition to this, the control operation amount in the air-fuel ratio feedback control (eg, proportional operation amount, integral operation amount), etc. May be Further, if the cam switching cannot be determined based on the change rate of the intake air amount within the predetermined time after the switching command is output, the ignition timing map is forcibly switched at the time when the predetermined time has elapsed. In addition, it is preferable to avoid that the ignition timing map is not switched because the change in the intake air amount cannot be detected.

Further, for example, a switch is provided for detecting that the plunger 31 of the variable valve mechanism 101 has moved to a predetermined position after the cam switching operation, and the switch moves the plunger 31 to the final position accompanying the switching operation. If it is not possible to determine the cam switching based on the change in the intake air amount before it is detected that the ignition timing map is switched in synchronization with the switch switching signal. May be.

[0046]

As described above, according to the engine control apparatus of the first aspect of the present invention, the valve opening characteristic is actually detected when the change in the intake air amount of the engine occurs after the valve opening characteristic switching command is output. When the characteristics are switched, the engine control value is switched at such timing, so when the actual valve opening characteristics are delayed in response to the switching command, the accuracy of the actual switching timing is improved. The engine control value can be switched in good synchronization, and the drivability of the engine at the time of switching the valve opening characteristic can be improved.

Further, in the apparatus according to the invention of claim 2,
Since the reference change rate of the intake air amount is set according to the valve opening characteristics before and after switching, even if the change characteristics of the intake air amount differ depending on the type of switching, the actual switching timing will be highly accurate. Can be discriminated. Furthermore, in the device according to the third aspect of the present invention, the ignition timing is switched based on the switching of the valve opening characteristic determined based on the change of the intake air amount. There is an effect that the ignition control can be performed even when the open characteristic is switched.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a system block diagram showing an embodiment of the present invention.

FIG. 3 is a diagram showing a variable valve mechanism of the embodiment.

FIG. 4 is a view showing a variable valve mechanism of the embodiment (IV- in FIG. 3;
IV cross section).

FIG. 5 is a view showing a variable valve mechanism of the embodiment (V- in FIG.
V sectional view).

FIG. 6 is a view showing a variable valve mechanism of the embodiment (VI- in FIG. 4;
VI cross section).

FIG. 7 is a flowchart showing cam / ignition timing switching control according to the embodiment.

FIG. 8 is a time chart for explaining problems of conventional control.

[Explanation of symbols]

 1 rocker arm 2 free cam follower 3 main rocker shaft 7 lever member 9 return spring 10 spring retainer 21 low speed cam 22 high speed cam 31 actuating plunger 34 hydraulic chamber 101 variable valve mechanism 102 control unit 103 switching valve 104 rotation speed sensor 105 air flow meter 106 Ignition device

Claims (3)

[Claims] 1. A valve opening characteristic switching means for switching a valve opening characteristic of an engine to a plurality of preset types, and a switching for outputting a valve opening characteristic switching command to the valve opening characteristic switching means according to an operating condition. An engine control device comprising: a command output unit; an intake air amount detection unit for detecting an intake air amount of the engine; and an intake air amount detected by the intake air amount detection unit after the switching command. Based on the switching timing discriminating means for discriminating the time point at which the rate of change exceeds a predetermined value as the timing at which the valve opening characteristic is actually switched, and the switching timing discriminated by the switching timing discriminating means, the valve opening characteristic And an engine control value switching means for switching the engine control value set to The engine control apparatus, characterized in that the. 2. The switching timing determination means sets a reference rate of change of the intake air amount according to the valve opening characteristics before and after the switching, and the reference rate of change and the intake air amount detected by the intake air amount detection means. 2. The engine control apparatus according to claim 1, wherein the timing at which the valve opening characteristic is actually switched is determined by comparing the change rate of the engine speed with the change rate. 3. The engine control value switched by the engine control value switching means is an ignition timing preset for each valve opening characteristic.
The engine control device according to any one of 1.