JP2810411B2 - Engine ignition timing control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ignition timing control device for an engine.

(Prior Art) In many engines, particularly automobile engines, the ignition timing is retarded when knocking of the engine is detected by a knock sensor.

The ignition timing control using the knock sensor is not sufficient to completely prevent knocking because it is performed after knocking occurs once. From such a viewpoint, it is considered that when an operation state in which knocking is likely to occur is detected, the ignition timing is retarded by a predetermined amount in a prospective control. That is, it has already been proposed to retard the ignition timing by a predetermined amount at the time of acceleration in which knocking easily occurs (see Japanese Patent Application Laid-Open No. 63-138164).

Incidentally, the basic ignition timing of the engine is generally determined by the engine speed and the engine load, and the intake air amount is often used as a parameter indicating the engine load. And
The basic ignition timing is also changed depending on the altitude, that is, the atmospheric pressure (see Japanese Patent Application Laid-Open No. 55-84867). Due to the low air density, the actual load of the engine will differ depending on the magnitude of the air pressure. To compensate for this difference, the basic ignition time is changed as described above (at high altitudes compared to low altitudes). Is changed to the more advanced side).

(Problems to be Solved by the Invention) By the way, in the case where the ignition timing is retarded at the time of acceleration, it has been found that if this retardation is performed at a high altitude, the acceleration performance is greatly impaired.

In pursuit of such a cause, it was found that the amount of retard was too large. In other words, if the retard amount is set so that knocking does not occur during acceleration in a lowland where the atmospheric pressure is large, the retard amount set for this lowland
At a high altitude, the retard amount is much larger than the retard amount necessary for preventing knocking, that is, an excessive retard angle.

Such a situation would occur similarly even when the basic ignition timing was changed according to the atmospheric pressure as described above. To explain this point in detail, when considering the operating region of the engine that is frequently used, the region is as shown by the solid line in FIG. 4 at low altitude. On the other hand, at a high altitude, if the accelerator opening is the same, the engine output is smaller than in a low altitude, so the driver tends to step on the accelerator greatly. For this reason, as shown by the broken line in FIG. 4, the operating range of the engine that is frequently used shifts to a higher load side as compared with the low altitude area as shown by the broken line in FIG. When setting the basic ignition timing at high altitude, there is room for advancing to obtain the best torque (knocking limit). Cannot be set with sufficient advance. As described above, since the basic ignition timing for highlands has to be set on the retard side considerably from the beginning,
If the vehicle is retarded by the same value as at low altitude during acceleration, it will be over retarded.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and assumes that the ignition timing is retarded by a predetermined amount during acceleration. It is an object of the present invention to provide an engine ignition timing control device capable of preventing acceleration from deteriorating.

(Configuration of the Invention) In order to achieve the above object, the present invention has the following configuration. That is, ignition timing adjustment means for adjusting ignition timing, acceleration detection means for detecting acceleration, and when acceleration is detected by the acceleration detection means, the ignition timing adjustment means is controlled to detect acceleration immediately after acceleration detection. Retarding means for retarding the ignition timing by a predetermined amount over a predetermined period of time; pressure detecting means for detecting pressure; when the pressure detected by the pressure detecting means is low, the pressure is higher than when the pressure is high. And retarding amount changing means for reducing the retarding amount by the retarding means.

(Effects and Effects of the Invention) With such a configuration, it is possible to optimally set the ignition timing retard amount at the time of acceleration according to the difference in air pressure, and to knock even in high altitude traveling with low air pressure. , And accelerated life can be sufficiently satisfied.

In particular, in the present invention, the acceleration response can be sufficiently satisfied by retarding the ignition timing in a prospective manner from immediately after acceleration detection to a predetermined period during acceleration detection.

(Example) Hereinafter, an example of the present invention will be described with reference to the attached drawings.

In FIG. 1, reference numeral 1 denotes a 4-cycle reciprocating Otto type engine main body, which is fitted in a cylinder block 2, a cylinder head 3 and a cylinder 2a of the cylinder block 2 as is known. A combustion chamber 5 is defined by the inserted piston 4. In the combustion chamber 5, a spark plug 6 is arranged, and an intake port 7 and an exhaust port 8 are opened.
The intake valve 9 or the exhaust valve 10 opens and closes at a known timing in synchronization with the engine output shaft.

In the intake passage 21 connected to the intake port 7, an air cleaner 22, an air flow meter 24 for detecting an intake air amount, a throttle valve 25, a surge tank 26, and a fuel injection valve 27 are sequentially arranged from the upstream side to the downstream side. ing. An air-fuel ratio sensor 29 and a three-way catalyst 30 as an exhaust gas purifying device are sequentially arranged in the exhaust passage 28 connected to the exhaust port 8 from the upstream side to the downstream side.

In FIG. 1, reference numeral 31 denotes a control unit constituted by a microcomputer. This control unit 31 includes a switch or sensors 32, 33, in addition to the signal from the sensor 24.
Signals from 34 and 41 are input. The switch 32 is an idle switch that detects that the throttle valve 25 is fully closed. The sensor 34 is attached to the distributor 36 and detects a crank angle, that is, an engine speed. The sensor 41 detects an atmospheric pressure.

Further, a predetermined signal is output from the control unit 31 to the igniter 37. That is, when a predetermined ignition timing signal is output from the control unit 31 to the igniter 37, the primary current of the ignition coil 38 is cut off, and a high voltage is generated on the secondary side thereof. Is the Distributor 36
Is supplied to the ignition plug 6 via the.

An outline of the control by the control unit 31 will be described with reference to FIG. 2 and FIGS. 3A to 3D.

First, the control unit 31 determines the basic ignition timing based on the engine speed and the intake air amount as in the related art.
The basic ignition timing is changed according to the air pressure, and is set to be more advanced when the air pressure is low than when the air pressure is high. The setting of the basic ignition timing according to the atmospheric pressure is as follows.
It can be performed in two or three or more steps according to the level of the atmospheric pressure, or can be performed continuously and variably.

Assuming that the air pressure is large, the ignition timing advance control during acceleration is changed according to the acceleration modes A to D shown in FIG. That is, the acceleration mode A is when the engine speed is 1500 rpm or less and the vehicle is accelerated from the fully closed state of the throttle. At this time, the ignition timing is retarded as shown in FIG. 3A. In the acceleration mode B, the engine speed is 1500
When the throttle valve 25 is accelerated from a state in which the throttle valve 25 is already open, the ignition timing is retarded as shown in FIG. 3B. The acceleration mode C is when the engine speed is higher than 1500 rpm and equal to or lower than 2500 rpm, and the engine is accelerated from the fully closed state of the throttle. At this time, the ignition timing is retarded as shown in FIG. 3C. Acceleration mode D
Means that the engine speed is greater than 1500rpm and 2500rpm
In the following case, the throttle valve 25 is accelerated from the already opened state, and the ignition timing retard at this time is the 3D
This is performed as shown in the figure.

Referring to FIG. 3A as a representative example, the retard during acceleration will be described. First, at the time of detecting acceleration, a large initial value is set as the retard amount. Thereafter, the retard amount is reduced for each ignition and reaches a predetermined end value, and then the retard amount is reset to zero by terminating the retard control during acceleration. Such a thing,
The same applies to FIGS. 3B to 3D. 3A, FIG. 3B, and FIG.
Figure 3C and Figure 3D. Such a difference in the amount of retardation according to the acceleration mode is based on the following reason. First, first
In addition, when accelerating from the fully closed state of the throttle, the amount of increase in the intake air amount is larger than when accelerating from the state where the throttle valve 25 is already open, that is, knocking is more likely to occur. Is made larger in FIG. 3A than in FIG. 3B, and is made larger in FIG. 3C than in FIG. 3D.
Further, since the knocking is more likely to occur when the engine speed is lower than when the engine speed is higher, the amount of retard is made larger in FIG. 3A than in FIG. 3C, and in FIG. 3B than in FIG. 3D. Is also increased.

The retardation as shown in FIGS. 3A to 3D according to the acceleration modes A to D described above is executed unconditionally when the atmospheric pressure is small. On the other hand, the atmospheric pressure has a certain value (for example, altitude
(Pressure corresponding to 00 m), the acceleration mode A
In the case of, the retardation is performed as shown in FIG. 3A in the same manner as when the atmospheric pressure is large, but in the remaining acceleration modes B to D, the retardation during acceleration is not performed (the amount of retardation is zero). However, when the air pressure is low, the retard amount is reduced as compared to when the air pressure is high, as shown as a high altitude (broken line) or a high altitude (dashed line) in FIG. The corners themselves may be implemented.

Next, determination of the ignition timing retard amount during acceleration will be described with reference to the flowchart shown in FIG.
In the following description, S indicates a step.

First, at S1, the engine speed N, the intake air amount Q, the atmospheric pressure P, and the operation state of the idle switch 32 are read. Thereafter, according to the discrimination between S2 and S3, the increase amount ΔQ of the intake air amount one time before the control cycle is smaller than a predetermined threshold (YES in S2), and the increase amount ΔQ of the current intake air amount is determined. Is greater than or equal to the predetermined threshold value (YES in S3), it is determined that the vehicle is accelerating.

When it is determined that the vehicle is accelerating, in S4, it is determined whether or not it is within a predetermined time after the idle switch 32 shifts from the ON state to the OFF state, that is, whether or not the acceleration is from the throttle fully closed state. Is determined. In this determination of S4
When YES, the execution condition of the retard is determined based on the engine speed and the atmospheric pressure. That is, when the engine speed is equal to or less than 1500 rpm, it is determined that the condition for executing the retardation as shown in FIG. 3A is satisfied in S6 regardless of the pressure. Further, when the engine speed is 2500rpm or less greater than 1500 rpm, and when pressure P is greater than a predetermined threshold value P ₀ in condition (S8, S9 YES together to discriminate) in Figure 3C It is determined that the condition for executing the retard as shown is satisfied. Thus, S6 or S1
When it is determined that the retard should be executed at 0, the retard amount is determined in S7 based on the determined execution condition (FIG. 3A or 3C). And the engine speed
When larger than 2500 rpm (when S8 in determination is NO), or when even pressure P engine speed is between 1500~2500rpm is smaller than the threshold value P ₀ (when the determination of S9 in NO), Is returned without any delay.

On the other hand, when the determination in S4 is NO, it means that the acceleration mode B or D shown in FIG. 2 is considered. Also at this time, the execution condition of the retard is determined based on the engine speed and the atmospheric pressure. That is, if the engine speed is 1500
When following rpm (in case of YES in the determination of S11), the condition that air pressure P is the threshold value P ₀ or (discrimination of S12 Y
When ES), a condition for executing the retarded as shown in Figure 3B in S13, it is determined as that satisfied, also pressure P is P ₀
If it is smaller than the value, the routine is returned as it is without retarding. When the engine speed is higher than 1500 rpm and equal to or lower than 2500 rpm (the determination in S14 is YES
When), when pressure P is P ₀ or more (the determination of S12 YES
It is determined step S16 when) with those conditions for executing the retarded as shown in FIG. 3D is satisfied, air pressure P is directly returned as not performed the retarded when less than P _0. Further, when the engine speed is higher than 2500 rpm (when the determination in S14 is NO), the process is returned as it is without retarding regardless of the pressure. Of course, if it is determined in S13 or S16 that the retard should be executed, then in S7, the amount of retard is determined based on the determined retard execution condition (FIG. 3B or 3D).

Although the embodiment has been described above, the acceleration determination level may be set to be higher when the air pressure is low than when the air pressure is high (for example, the threshold value of S3 and S4 in FIGS. Is greater than when the air pressure is higher).

[Brief description of the drawings]

FIG. 1 is a system diagram showing one embodiment of the present invention. FIG. 2 is an explanatory view showing an acceleration mode. 3A to 3D are diagrams showing examples of setting the retard amount according to the acceleration mode. FIG. 4 is a view showing a difference in an operation range of an engine frequently used between a lowland and a highland. FIG. 5 is a flowchart showing a control example of the present invention. FIG. 6 is a block diagram showing the configuration of the present invention. 1: engine 6: spark plug 24: sensor (intake air volume) 25: throttle valve 31: control unit 32: idle switch 34: sensor (engine speed) 37: igniter 38: ignition coil 41: sensor (barometric pressure)

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02P 5/15

Claims (1)

(57) [Claims] An ignition timing adjusting means for adjusting an ignition timing; an acceleration detecting means for detecting acceleration; and controlling the ignition timing adjusting means when acceleration is detected by the acceleration detecting means. A delay means for delaying the ignition timing by a predetermined amount over a predetermined period during acceleration detection; a pressure detection means for detecting air pressure; and when the pressure detected by the pressure detection means is low, it is higher than when it is high. An ignition timing control device for an engine, comprising: a retard amount changing means for reducing a retard amount by the retard means.