JPS61169641A - Valve timing control device for internal-combustion engine with knocking control device - Google Patents

Abstract

PURPOSE:To correct the control center of an ignition timing to the center of a control range and to improve fuel consumption and prevent the occurrence of transient knocking, by a method wherein, when the control center of the ignition timing is displaced from the center of a control range to the delay side, delay correction is applied on a valve timing. CONSTITUTION:Lead angle control or delay angle control is effected on the ignition timing of an internal-combustion engine 2 by a knocking control device 1 by means of a signal from a knocking sensor 1', and this prevents the occurrence of knocking. In this device, a valve timing control means 3 is provided for controlling the valve timing of the variable valve timing mechanism of the internal-combustion engine 2. Additionally,, a detecting means 5 is provided for detecting that an ignition timing controlled by the knocking control device 1 is regulated closer to the angle of delay side than a given value. The valve timing control means 3 is controlled by a valve timing delay setting means 6 so that the ignition time is adjusted to a valve timing on the angle of delay side by means of a signal from the detecting means 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an internal combustion engine that uses a variable valve timing mechanism and a knock control device that controls knocking by controlling ignition timing.

BACKGROUND OF THE INVENTION Conventional knocking control devices are known that control knocking by controlling ignition timing. In this type of device, a knock sensor, which is a converter that converts the engine's mechanical vibrations into electrical vibrations, is installed in the internal combustion engine, and when knocking is detected by the knock sensor signal, the ignition timing is retarded. When knocking is not occurring, the ignition timing is advanced, and this is repeated to control knocking.

Problems to be Solved by the Invention In the aforementioned knock control device that controls knocking by controlling the ignition timing, the basic ignition timing determined by the basic operating conditions of the engine is set to the most advanced side, and this basic ignition timing is set to the most advanced side. The ignition timing is calculated by subtracting the delay correction value corresponding to knocking from the timing, and control is performed so that ignition is performed at the corrected ignition timing. In this case, the correction amount is centered around the average value to prevent knocking.
It is increased or decreased depending on the presence or absence of knocking within the correctable range. Therefore, the ignition timing, which is the difference between the basic ignition timing and the corrected value, is repeatedly retarded and advanced around the average ignition timing. The central value of the ignition timing varies depending on the engine, and the central value may be significantly retarded. In this case, the fuel consumption rate deteriorates, which is not preferable. Furthermore, as mentioned above, the range of corrections that can be made to the ignition timing is limited because it is a measure against failures, and there is no margin to retard the ignition timing in the event of a sudden change in load, making it impossible to retard the ignition timing sufficiently. , transient knocking occurs.

Means for Solving the Problems The present invention attempts to solve the above-mentioned problems by combining a knocking control device with a valve timing control device. That is, in FIG. 1 showing the configuration of the present invention, reference numeral ``2'' is a knocking control device, which controls the ignition timing of the internal combustion engine 2 based on a signal from a knock sensor 1' to control knocking. The valve timing control device is
Valve timing control means 3 controls the valve timing of the engine; detection means 5 detects that the ignition timing controlled by the knocking control device l is on the retard side than a predetermined value; Valve timing control means 3 so that the valve timing is on the corner side.
and a valve timing retard setting means 6 for setting the valve timing obtained by.

The knock control device 1 advances or retards the ignition timing in response to a signal from the knock sensor 1'.

When the ignition timing is on the retarded side based on the signal from the ignition timing retard detection means 5, the valve timing is set to a value on the retarded side by the setting means 6. By retarding the valve timing, a margin for knocking is created, and the knocking control device can efficiently perform knocking control.

Example FIG. 2 shows the overall configuration of this invention.

10 is a cylinder block, 12 is a piston, 14 is a connecting rod, 16 is a crankshaft, 18 is a cylinder head, 20 is an intake valve, 22 is an intake boat, 24 is a spark plug, 26 is an exhaust valve, 28 is an exhaust boat, 30 32 is an intake camshaft, 32 is an exhaust camshaft, 34 and 36 are valve springs, and 38 is a distributor. In this embodiment, two camshafts 30 and 32 are installed, so-called DOHC.
This invention can also be applied to SOHC engines. Crankshaft 16, intake camshaft 30
, timing pulleys 44 and 46 on the exhaust camshaft 32, respectively.
are provided, and these pulleys 44, 46 are connected to the crank pulley 42 by a timing belt 48.

A variable valve timing mechanism 52 is connected to the intake side camshaft 30. Various known types of variable valve timing mechanisms can be employed, and for example, the configuration shown in FIG. 3 can be adopted. The variable valve timing mechanism 52 is of a type that controls valve timing by twisting the intake cam 30 relative to the crankshaft 16. This variable valve timing mechanism was developed in Japanese Patent Application Laid-open No. 58-
135310. To explain this, as shown in FIG. 3, an inner sleeve 6o is attached to one end of the camshaft 30 by a bolt 62, and an outer sleeve 64 is rotatably attached to the inner sleeve 60 by a bearing 66. The boo IJ44 that transmits rotation from the crankshaft 16 is provided on the outer sleeve 64. inner sleep 6o
, arcuate projections 60A, 64A from the outer sleeve 64.
extend alternately over about 90 degrees as shown in FIG. Opposing edges 6o' of adjacent protrusions.

As shown in FIG. 5, one side of 64' is straight, but the other side is inclined with respect to the axis of camshaft 30. Bearings 70, 72 are arranged in separate contact between the opposing edges 60', 64'. Bearing 70.72
There are four sets, and they are attached to the sleeve 74. The sleeve 74 is rotatable on a NAND 76 via a bearing 75, and the nut 76 is fitted into a threaded portion of a drive shaft 78A of a step motor 78. The nut 76 has an axial groove 76A which serves as an axial guide 78B on the motor housing.
is fitted. Therefore, the rotation of the step motor 78 is converted into an axial movement of the nut 76, and the bearings 70, 72 on the sleeve 74 move in the direction of the arrow in FIG.
(in the axial direction). Opposite edges 60', 64' of inner sleeve 60 and outer sleeve 64 are mutually angled, thereby causing relative rotation of these sleeves. As a result, relative rotation occurs between the pulley 44, ie, the crankshaft 16, on the outer sleeve 60 side and the camshaft 30 on the inner sleeve 64 side. Rotation of the step motor 78 in one direction (referred to as normal rotation) causes the shaft 30 to be twisted in a direction in which it advances relative to the crankshaft 16, and rotation in the other direction (referred to as reverse rotation) causes the camshaft 30 to twist relative to the crankshaft 16. Twisted in the direction of being late.

Figure 6 (a) is a valve timing diagram at the most advanced position, where the intake valve 20 begins to open at an angle of α (1,0) before top dead center TDC, and at an angle of β after bottom dead center BDC. Finish closing at an angle (1.C). On the other hand, (b) is the valve timing diagram at the most delayed position, where the intake valve is α'(<α) before TDC.
It begins to open at an angle of (1°0) and finishes closing at an angle of β'(>β) after BDC (1.C). As will be described later, the step motor 78 is driven to provide optimum valve timing between positions (a) and (b) depending on operating conditions.

In this embodiment, the valve timing of the exhaust valve 26 is (
It is common to A) and (0), and it starts opening in front of BDC (E
.

0), and finishes closing after TDC (E, C).

In FIG. 2, reference numeral 86 indicates a control circuit for controlling ignition timing and valve timing according to the present invention, and is configured as a microcomputer. The control circuit 86 receives signals from the following sensors. That is, the first and second crank angle sensors 79 are connected to the distributor 38.
．． 80 are provided. The first crank angle sensor 79 cooperates with a permanent magnet piece 38b installed on the distribution shaft 38a of the distributor 38 to generate a pulse every revolution of the engine and generate a basic signal for ignition timing control to be described later. A second crank angle sensor 80 cooperates with a second permanent magnet piece 38c on the distribution shaft to provide a predetermined crank angle, e.g. 30"CA.
A pulse is generated every time, the engine rotation speed Ne is known, and it also serves as an interrupt signal in ignition control.

The air flow meter 82 generates a signal corresponding to the intake air IQ entering the engine from the intake pipe, and may be of a well-known type consisting of a temporary damper and a potentiometer attached to its center shaft.

Further, the knock sensor 84 is attached to the sill block 10, and can be of a type that converts mechanical vibrations of the engine into electrical vibrations.

The control circuit 86 calculates ignition timing and valve timing according to a program to be described later, and applies control signals to the igniter 88 and the step motor 78 of the variable valve timing mechanism 52 described above. The igniter 88 consists of an ignition coil and a drive circuit, and a high voltage current is generated in the ignition coil by the fall of the ignition pulse to the drive circuit, and a spark is formed at the ignition plug 24 of the cylinder designated by the distributor 38. Operate.

The control circuit 86 consists of a microprocessing unit (MPU) 861, a memory 862, an input port 863, and an output port 864, as shown in FIG. Input port 86
3 is connected to crank angle sensors 79 and 80, and
It has an analog-digital (A/D) conversion function and is connected to an air flow meter 82 and a knock sensor 84. A band pass filter (BPF) 865 and a peak hold circuit 8 are provided between the knock sensor 82 and the input port 863.
There is a knocking detection circuit comprising 68 and a gate not shown. Among the signals from the knock sensor 84, only signals in a frequency band related to knocking are extracted by the BPF 865 (FIG. 7(a)). At a certain crank angle after top dead center (TDC), which is the knocking detection period,
The gate (8) opens, and the peak hold circuit 868 holds the peak in the knock sensor signal (a) (
B). The presence or absence of knocking is determined by comparing this peak signal with a predetermined background level.

Output port 864 is connected to stepper motor 78 and nogniter 88 . A valve timing control signal and an ignition control signal are set to the output port 864 according to a program described later. As a result, step motor 78 and igniter 88 are operated to achieve the calculated valve timing and ignition timing.

A program for controlling ignition timing and valve timing according to the present invention is stored in the memory 862 of the control circuit 86. This program will be explained below using a flowchart. FIG. 8 is a flowchart schematically showing the ignition timing control routine as far as it is related to the present invention. The point 100 indicates the start of this program, and this routine starts with the first crank angle sensor 79.
This shows an interrupt routine that is started to be executed by a pulse signal every 30'CA from . At 102, it is determined whether or not there is a crank angle region in which knocking detection processing is to be performed. In combination with the signal from the first crank angle sensor 79, it is possible to know which cylinder is experiencing knocking. If Yes, the process proceeds to step 103, where the peak signal held in the peak hold circuit 868 is A/D converted, and the peak value N is stored in a predetermined area of the memory 862. In step 104, it is determined whether or not knocking has occurred by comparing a predetermined level (referred to as a background level) b, which is a reference for determining whether knocking has occurred, with a peak level N. For example, if N≧kb (k: positive constant), it is determined that knocking has occurred, and the process proceeds to 106, where the ignition timing retardation correction amount Δθ is incremented by ao.

In step 107, it is determined whether △θ is larger than the maximum value X° of the retard angle correction width, and if it exceeds the maximum value, the process proceeds to 108, where Xo is entered in △θ, and the retard angle correction value is set to be larger than Xo. It is designed not to grow large.

If there is no knocking, it will be determined as No at 104, and 10
The process proceeds to step 9, where the retard angle correction amount Δθ is decremented by ao. In step 110, it is determined whether 80 is smaller than Oo, which is the lower limit of the retard angle correction amount.

If Yes, Oo is inserted into 80 in step 111. Through the above control, the retard angle correction amount Δθ is increased or decreased within the range between the maximum value X° and the minimum value 0°, depending on the presence or absence of knocking.

In step 112 of Fig. 8, the basic ignition timing θBASH
The ignition timing θ is obtained by subtracting the retardation correction amount Δθ calculated as described above. Here is the basic ignition timing θBA
As is well known, SE is calculated from the intake air amount Q from the air flow meter 82 and the rotational speed Ne calculated by the second crank angle sensor 80.

Step 114 indicates an ignition processing step, in which a signal is supplied to the igniter 88 so that the next time the cylinder is ignited, the ignition is performed at the timing θ calculated in 116. This process is well known and is not directly related to the features of the present invention, so its explanation will be omitted.

FIG. 9 shows a valve timing control routine, which starts execution from point 200 at every predetermined time interval (for example, 5 m5ec). At 202, the ignition timing retardation correction amount Δθ calculated at 106 and 109 in FIG. 8 reaches the predetermined value. It is determined whether or not the correction amount on the delayed side is smaller than that, that is, the correction amount on the delayed side is larger. This △θ. The value of should be set to an appropriate value that is slightly larger. No in 202, that is, the ignition timing retard correction is △θ. (If not, normal valve timing control is performed. In other words, at 204, the engine speed,
N e In 5206, the intake air amount to rotational speed ratio Q/Ne is input, and in step 208, the actually measured Ne, Q
A step motor shaft position setting value Vstep, which determines the valve timing, is calculated from /Ne. Here Vs te
p=0 corresponds to the step motor shaft position that takes the most retarded valve timing shown in FIG. 6 (b), and Vs step
As becomes larger, the step motor shaft position approaches the valve timing shown in FIG. As is clear from the explanation of FIG. 3, the valve timing changes depending on the position Vs step of the rotating shaft 78A of the step motor 78, but in the memory 862, Vstep is determined by the rotation speed Ne and the ratio Q/Ne. For example, it is mapped as shown in Figure 10. MPU361 has actually measured Ne, Q/
The target value of Vs step (for example, point X in FIG. 10) is calculated from Ne. In the next step 209, the value obtained by subtracting δ from Vstep is set as Vs step. δ is the valve timing delay correction amount corrected by the ignition timing delay correction amount Δθ, and will be described in detail later.

In the next step 210, the target value Vs step is compared with the current axial position 1Vveal of the step motor 78, and if there is a deviation, the process branches to NO, and in 212 Vstep is
>Vreal, that is, whether the deviation is on the plus side or not is determined. If Yes, it is recognized that it is necessary to turn the step motor 78 to the advance side of the valve timing, and the V
After incrementing rea 1, the step motor 78 is rotated forward by one step at 216.

When 212 is NO, it is recognized that it is necessary to turn the step motor 78 to the valve timing delay side, and 218 is set to V.
After decrementing real, step motor 78 is reversed by one step at 220.

By controlling the rotation of the step motor 78 in this manner, the valve timing is controlled to a predetermined value according to the map shown in FIG.

Due to variations in the engine, the center value of the ignition timing may shift to the delayed side; in this case, △θ becomes △θ. It becomes larger and closer to X.

Therefore, the determination at step 202 in FIG. 9 is YES. In this case, the process proceeds to 226, where the valve timing delay correction amount δ is corrected to the retard side. In other words, when the amount of deviation of the ignition timing from the control center to the delay side increases as shown on the horizontal axis in Figure 11, if the delay of the valve timing is increased as shown on the vertical axis, the control center of the ignition timing can be changed. Any deviation from the center of the range is eliminated. That is, when the valve timing is delayed, the effective compression ratio becomes smaller, which makes knocking less likely, and the ignition timing returns to the advanced side, so the ignition timing is controlled around the center of the variable range.

To explain this with reference to FIG. 6, the step motor 78
moves between the leading side extreme position (a) and the lagging side extreme position (b). In the position (a), effective compression in the compression process starts from the crank angle of BDCβ at which the intake valve closes, and the effective compression stroke is 2. On the other hand, in (o), the effective compression starts from BDCβ′ and the effective compression stroke is j! z(<l1l). Comparing (a) and (0), the former has a larger effective compression ratio than the latter and is more likely to cause knocking. Therefore, when the control center of ignition timing deviates from the center of its control range, by delaying the valve timing in accordance with the deviation, it is possible to bring the control center of ignition timing into line with the center of its controllable range. .

That is, in step 226, the current δ plus b is set to δ. Therefore, by executing the routines 209 and below, the valve timing is corrected to be delayed by b from the value determined by the map in FIG. By repeating such an operation several times, the determination at 202 is switched to NO, and the ignition timing correction amount Δθ is in the middle of the variable range or Δθ close to it.

It will be corrected and controlled to be equal to .

Note that the area of the memory 862 that stores the value of δ is a non-volatile RA.
If M, the corrected value of δ is retained even after the engine key is turned off. Therefore, the ignition timing is approximately in the middle of its control range from the start of the restart, and the ignition timing is optimally controlled immediately after the restart, eliminating unnecessary retardation.

Further, the valve timing control device is not limited to that of the embodiment, and the present invention can equally be applied to devices equipped with other types of valve timing control devices.

Effects of the Invention When the control center of ignition timing deviates to the lag side from the center of its control range, the control center of ignition timing is corrected to the center of the control range by delaying and correcting the valve timing. As a result, the fuel consumption rate is improved and the occurrence of transient knocking is prevented.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of this invention. FIG. 2 is a configuration diagram of the embodiment. FIG. 3 is an axial cross-sectional view of the variable valve timing mechanism in the embodiment. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. FIG. 5 is a view taken from the ■ direction arrow in FIG. Figure 6 is a valve timing diagram. FIG. 7 is a diagram illustrating signal processing of the knock sensor. FIGS. 8 and 9 are flowcharts illustrating the software of the present invention. Figure 10 is a valve timing map. FIG. 11 is a graph schematically showing the relationship between the ignition timing delay correction amount and the valve timing delay amount necessary to maintain the delay correction amount at an intermediate value. 20-Intake valve, 22-Exhaust valve, 30.32-Camshaft, 52-Variable valve timing mechanism, 78--Step motor, 84--Knock sensor, 86-Control circuit. Fig. 1 1-m-Knock sensor 2-m-Engine body 3-1-Valve timing control means Fig. 4 Fig. 5■ Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 311 Fig. Toward the momme lag direction amount of deviation

Claims (1)

[Claims] In an internal combustion engine equipped with a knocking control device that controls knocking by controlling ignition timing, the engine includes a valve timing control means that controls engine valve timing, and an ignition timing controlled by the knocking control device that is retarded from a predetermined value. an internal combustion engine comprising: a detection means for detecting that the valve timing is on the retarded side; and a valve timing retard setting means for setting the valve timing obtained by the valve timing control means so that the valve timing is on the retarded side based on a signal from the detection means. valve timing control device.