JP2506863Y2 - Engine idle speed controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an idle speed control device for an engine.

(Prior Art) Engines, particularly automobile engines, often perform feedback control so that the engine speed becomes a target idle speed during idling.

When performing such feedback control,
As shown in Japanese Patent Laid-Open No. 58-190572, there is a system in which the ignition timing is a control target. As described above, when the engine speed is set to the target idle speed by controlling the ignition timing, the ignition timing is set in a predetermined control range, that is, in order to avoid the problem of knocking and the problem of misfire. Limitations are made so that the range is between an upper limit value (a limit value to the advance side) and a lower limit value (a limit value to the retard side). It is desirable that the control range be set as wide as possible so as to cope with a large fluctuation of the engine speed, and the upper limit value is set as large as possible in a range where knocking does not occur in order to improve fuel economy.

(Problems to be solved by the invention) By the way, when the external load on the engine, for example, the power steering or the air conditioner is operating, a larger engine torque is required to maintain the same engine speed as compared with the non-operating time. Need. Therefore, when the external load is activated, the engine speed temporarily drops below the target idle speed, and then the engine is returned to the desired idle speed by feedback control of the ignition timing.

However, in the conventional device, knocking is likely to occur immediately after the external load is activated, and a countermeasure for this point is required. Explaining this point in detail, knocking is more likely to occur as the engine rotational speed decreases, so that a temporary reduction in engine rotational speed due to the operation of the external load is likely to cause knocking. On the other hand, as described above, in order to maintain the target idle speed, the upper limit value must be increased, and therefore knocking immediately after the external load is activated is difficult to avoid. Of course, in order to prevent knocking immediately after the external load is actuated, the upper limit value may be set to a small value originally, but in this case, fuel deterioration and the adjustment range of the rotational speed become small,
Not preferred.

In Japanese Patent Laid-Open No. 63-306285, when the idle rotation control is performed by controlling the ignition timing, when an external load on the engine, such as a power steering or an air conditioner is operated, ignition is continuously performed during the operation of the external load. It is disclosed that the timing advance angle correction is prohibited to avoid knocking. However, with the one described in this publication, even if knocking can be avoided, it is not possible to sufficiently prevent the idle speed from decreasing. That is, the above publication discloses an upper limit correction means for reducing an upper limit value which is a limit value on the advance side of the ignition timing in association with the operation of an external load in order to prevent an excessive advance angle in the present invention described later. However, nothing is disclosed.

(Purpose of Invention) The present invention was made in consideration of the above circumstances.
In the feedback control so that the engine speed becomes the target idle speed by the ignition timing control, knocking immediately after the external load is activated can be prevented without sacrificing the fuel consumption and the adjustment range of the speed. It is an object of the present invention to provide an idle speed control device for such an engine.

(Configuration of the Invention) In order to achieve the above object, the present invention has the following configuration. That is, at the time of idling, by controlling the ignition timing within a control range between a preset upper limit value and a lower limit value, feedback control is performed so that the engine speed becomes the target idle speed. In the idle speed control device, an operating state detecting means for detecting an operating state of an external load with respect to the engine, and a predetermined period from the time when the operating state detecting means detects that the operation of the external load has changed in the increasing direction of the load. The inside is configured to include an upper limit correction unit that corrects the upper limit to be small.

(Operation and effect of the invention) In the present invention having such a configuration, when the external load is not operating, the upper limit value of the ignition timing is increased to improve the fuel consumption and increase the rotation speed. Can be secured.

Further, when the external load operates, the upper limit value is decreased for a predetermined period from the start of the operation, that is, the upper limit value is changed to the retard side, so that knocking is prevented.

Even if the upper limit is corrected to a small value, the period of this correction is when the engine speed is reduced, so
Enough engine torque can be secured to quickly return to the target idle speed. That is, if the ignition timing is the same, the engine torque becomes larger when the engine speed is small than when it is large (if the same engine torque is obtained, when the engine speed is small, it becomes larger than when it is large). Ignition timing can be set to a more retarded side).

(Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes an Otto type engine body of a 4-cycle reciprocating type. The engine body 1 is fitted into 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. A spark plug 6 is arranged in the combustion chamber 5, and an intake port 7 and an exhaust port 8 are opened, and these ports 7 and 8 are
The intake valve 9 or the exhaust valve 10 opens and closes at a known timing in synchronization with the engine output shaft.

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

Reference numeral 31 in FIG. 1 is a control unit constituted by a microcomputer, and signals from switches or sensors 32, 33, 34, 41 are input to the control unit 31. The switch 32 is an idle switch that is turned on when the throttle valve 25 is fully closed. The sensor 33 is a water temperature sensor that detects the cooling water temperature of the engine. Sensor 34
Is attached to the distributor 36 and detects the crank angle, that is, the engine speed. Switch 41
Is for detecting whether or not the external load is activated, and is turned on when the external load is activated.

Further, the control unit 31 outputs a predetermined signal 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, a high voltage is generated on the secondary side thereof, and the high voltage on the secondary side is distributed to the distributor.
It is supplied to the spark plug 6 via 36.

Next, regarding the contents of control by the control unit 31,
This will be described with reference to the flowchart in the figure. In the following description, S represents a step, and in FIG. 5, it is premised that the engine is idle (when the engine is idle, for example, except when the engine is started, the idle switch 32 is ON and It is determined that the engine speed is below a predetermined value).

First, after data is input from each sensor or switch in S1, various control values are set in S2. Of these various control values, NT is the target idle speed, IGB is the basic ignition timing at idle, and IGmax
1 is a basic upper limit value of the ignition timing, IGmax · 2 is a correction upper limit value within a predetermined period after an external load (power steering in the embodiment) operates, and IGmin is a lower limit value of the ignition timing. The target idle speed NT is set to a constant value such as 750 rpm when the water temperature is equal to or higher than a predetermined value (for example, 60 ° C.), and is increased as the water temperature becomes lower when the water temperature is lower than the predetermined value. The basic ignition timing IGB and the upper and lower limit values IGmax · 1, IGmax · 2, IGmin are changed in accordance with the water temperature (increase as the water temperature becomes lower), similarly to the change in the target idle speed NT. In the embodiment, when the target idle speed NT is 750 rpm, the basic ignition timing IGB is 10 ° (crank angle before top dead center-the same applies below), I
Gmax · 1 is 15 °, IGmax · 2 is 12 °, and IGmin is 5 °.

After S2, in S3, by subtracting the target idle speed NT from the current engine speed N, the rotation deviation Δ
N is calculated. After that, in S4, the feedback correction amount IGF of the ignition timing is determined according to the deviation ΔN.
Of course, this IGF is set to a value on the advance side (positive value) to increase the engine speed when ΔN is negative, and to the retard side to decrease the engine speed when ΔN is positive. Value (negative value). The IGF is increased as the absolute value of ΔN is increased. Then, in S5, the basic ignition timing IG
The corrected ignition timing IGM is calculated by adding the feedback correction amount to B.

In S6, it is determined whether or not the power steering is ON, that is, within a predetermined time (for example, 2 seconds) after being operated. If NO in this determination in S6, the corrected ignition timing IGM is set to the basic upper limit value IGmax · 1 and the lower limit value by the processing in S7 to S11.
Limit processing is performed so that the range is between IGmin.
Then, the ignition timing after the limit process is set as the final ignition timing IG (see S9, S10, S11), and the ignition is executed at the timing of this final ignition timing IG in S14.

On the other hand, when the determination in S6 is YES, the upper limit value of the ignition timing is limited by the corrected upper limit value IGmax.2 smaller than the basic upper limit value IGmax.1. That is, the corrected ignition timing IGM is corrected upper limit value IGmax
When it is determined that it is not 2 or less, the final ignition timing IG is set to the correction upper limit value IGmax · 2. Note that YES is determined in S12.
At this time, the limit process by the lower limit value IGmin is performed by the processes of S8, S9, and S10.

In FIG. 2, the above-mentioned control content is shown diagrammatically focusing on before and after the external load is activated. That is, the second
The time t1 in the figure is when the external load starts to operate, and at this time, the engine speed significantly decreases. Then, at this time, within the predetermined time from the time point t1, the ignition timing is subjected to limit processing so as not to exceed the corrected ignition timing IGmax · 2 (If the corrected ignition timing IGM is left, the decrease range of the engine speed is large. , IGmax · 1 or more).

Here, FIG. 3 shows the relationship between the ignition timing, the engine speed and the engine torque. In FIG. 3, the α line indicates the engine speed of 750 rpm, and the β line indicates the engine speed of 500 r.
It shows the time at pm. As is clear from FIG. 3, it is shown that the same engine torque as when the ignition timing is 15 ° at 750 rpm is obtained at the ignition timing of about 10 ° at 500 rpm. Therefore, at the time t1 in FIG. 2, even if the engine speed greatly decreases, for example, 500 rpm, if the ignition timing is 12 °,
The speed is set to 750 rpm and the target idle speed can be quickly returned to.

FIG. 4 shows the relationship between the engine speed, the ignition timing, and the knocking zone. The area above the γ line in FIG. 4 is the knocking zone. As is apparent from FIG. 4, even if the ignition timing G1 (corresponding to IGmax · 1) does not enter the knocking zone at 750 rpm, the ignition timing G1 enters the knocking zone at 500 rpm (the cause of knocking of the conventional one). On the other hand, at 500 rpm,
By making the ignition timing smaller than G1 such as G2 (corresponding to IGmax · 2), entry into the knocking zone is prevented.

Although the embodiments have been described above, the idle speed control according to the present invention can be performed together with the idle speed control by adjusting the intake air amount that is conventionally performed together. Further, the period in which the upper limit of the ignition timing is corrected after the external load is activated may be set by the number of ignitions after the external load is activated.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention. FIG. 2 is a time chart schematically showing the control contents of the present invention. FIG. 3 is a diagram showing a relationship among ignition timing, engine speed, and engine torque. FIG. 4 is a diagram showing the relationship between ignition timing, engine speed, and knocking zone. FIG. 5 is a flow chart showing a control example of the present invention. 1: Engine 6: Spark plug 25: Throttle valve 31: Control unit 32: Idle switch 33: Sensor (cooling water temperature) 34: Sensor (engine speed) 37: Igniter 38: Ignition coil 41: Switch (external load activation detection) for)

Claims (1)

(57) [Scope of utility model registration request] 1. At the time of idling, by controlling the ignition timing within a control range between a preset upper limit value and a lower limit value, feedback control is performed so that the engine speed becomes a target idle speed. In the idle speed control device for the engine, the operating state detecting means for detecting the operating state of the external load with respect to the engine, and the point of time when the operating state detecting means detects that the operation of the external load changes in the increasing direction of the load. And an upper limit correction unit that corrects the upper limit so that the upper limit becomes smaller within a predetermined period.