JP2730120B2 - Idle adjustment method for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for adjusting the idling of an internal combustion engine.

(Prior Art) A bypass passage for bypassing a throttle valve of an internal combustion engine and a bypass valve for adjusting an air flow rate in this passage are provided, and according to a deviation between a target idle speed and an actual engine speed during idle operation of the engine. There is known an idle speed control device that opens and closes a bypass valve to feedback-control an engine speed near a target idle speed.

At the time of shipping or maintenance of an internal combustion engine equipped with such an idle speed control device, if an attempt is made to adjust the idle speed by adjusting the bypass adjustment screw or the throttle adjustment screw, the idle speed control device reduces the engine speed. Since the bypass valve is opened and closed so as to be maintained at the target idle speed, it is impossible to adjust the idle speed in such a situation. Therefore, when adjusting the idle speed, it is necessary to fix the output of the idle speed control device, set the bypass valve to a predetermined opening or fully close, and operate the engine in a constant operating state.

On the other hand, it is necessary to adjust the ignition timing at the time of shipment or maintenance of the engine. In an internal combustion engine equipped with an ignition timing control device that electronically controls the ignition timing, the ignition timing during idle operation is fixed to a predetermined value, and while monitoring with a timing light, an ignition timing adjustment mark engraved on a crank pulley is provided. The distributor housing is rotated and adjusted so that the indicator pins are aligned with each other (generally referred to as swing adjustment of the distributor).

(Problems to be Solved by the Invention) In many engines, the above-described adjustment of the idle speed and the adjustment of the ignition timing are generally performed separately. For example, first, after the swing of the distributor is adjusted, The idle speed is adjusted by increasing or decreasing the idle air amount by a bypass adjusting screw. If the ignition timing adjustment and the idle speed adjustment are performed separately as described above, there is a problem that it takes time and effort.

Therefore, the valve opening of the bypass valve is fixed to a predetermined value and the ignition timing is also fixed to a predetermined value, and the above-described adjustment of the ignition timing and the adjustment of the idle speed (the ignition timing adjustment and the idle speed are referred to throughout the present specification). For example, Japanese Patent Application Laid-Open No. Sho 56-52573 discloses a method of performing both adjustments at one time (referred to as "idle adjustment"). To illustrate this conventional method with reference to FIG. 3, now in regular idle speed N _ST to be controlled during normal idling of the normal mode (e.g., 800 rpm), normal spark advance IG
It is assumed that _ST (for example, 15 ° BTDC) is set (operating point B ′ in FIG. 3). Then, the bypass valve is fully closed in the idle adjustment (during adjustment mode), the predetermined value IG _O the spark advance
(E.g., 5 ° BTDC) was respectively set to the idle speed is assumed to modulate the bypass adjusting screw to match the normal idle speed N _ST described previously (operating point of FIG. 3 A), these and the end of adjustment, at the time the engine returns to the operating state of the normal mode, in order to spark advance normal spark advance IG _ST (15 °) from a predetermined value IG _O (5 °) is advanced to the vicinity of The rotation speed increases by the amount of advance, and the idle rotation speed increases to a rotation speed N _H (for example, 900 rpm) higher than the normal idle rotation speed N _ST (800 rpm) (the operating point A in FIG. 3). ').

Therefore, in order to obtain the normal idle speed N _ST (800 rpm) in the normal mode operation after the adjustment, the idle speed at the time of the adjustment is adjusted to the normal idle speed N _{ST in consideration of the} increase in the speed due to the advance angle. Lower predetermined rotation speed N _L (for example, 700
rpm) (operating point B in FIG. 3). However, when the idle adjustment is performed at such a low idle speed, the speed is greatly fluctuated at a low speed, and the adjustment is difficult due to lack of stability. Further, there is also a disadvantage that the normal rotational speed _NST during normal mode operation is different from the normal rotational speed _NL during adjustment, so that the correct rotational speed is easily erroneous.

The present invention has been made to solve such a problem, and provides an idle adjustment method for an internal combustion engine in which the engine can be maintained in a stable operation state with little rotation fluctuation during idle adjustment and idle adjustment is easy. The purpose is to do.

(Means for Solving the Problems) According to the present invention, in order to achieve the above object, a bypass valve is provided in a bypass passage that bypasses a throttle valve provided in an intake passage. The engine further comprises idle adjusting means for adjusting the intake air amount when the valve and the bypass valve are fully closed by an artificial operation, and adjusts the intake air amount by the bypass valve during idle operation when the throttle valve is in a fully closed state to reduce the engine speed. While controlling near the target idle speed, the idle time is adjusted by the idle adjusting means at the time of idle adjustment, and the ignition timing and the engine speed in the standard idle operation state are set to the normal ignition advance angle and the normal idle speed, respectively. In the idle adjustment method for the internal combustion engine to be controlled, the ignition timing is fixed to a predetermined value different from the normal ignition advance during the idle adjustment. In addition, after the operation amount of the bypass valve is fixed to a predetermined value corresponding to the rotation speed change amount that is changed when the ignition timing is changed from the normal ignition advance to the predetermined value, the engine speed is reduced to the normal idle speed. An idle adjustment method for an internal combustion engine is provided, wherein the idle adjustment means is adjusted to match the rotation speed.

(Operation) In general, when the ignition timing is retarded, the engine speed decreases, but the operation of the engine is stabilized. In the idle adjustment method of the present invention, at the time of idle adjustment, the ignition timing is fixed to a predetermined value different from the normal ignition advance, preferably a predetermined value delayed from the normal ignition advance, and the operation amount of the bypass valve is adjusted to the ignition timing. The value is fixed to a predetermined value corresponding to the rotation speed change amount that changes when the normal ignition advance angle is changed to a predetermined value. Therefore, the engine speed at this time is maintained at a speed close to the normal idle speed, and the operation of the engine is stabilized. In this state, the engine speed is adjusted by the idle adjusting means to an adjusted speed that is the same value as the normal idle speed.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of an idle speed adjusting device for carrying out the method of the present invention. In FIG. 1, reference numeral 1 denotes, for example, a four-cylinder gasoline engine, and an intake manifold 2 is connected to each cylinder of the engine 1, Manifold 2 is surge tank 2a
And is connected to the intake pipe 3 via the. An air cleaner (not shown) is attached to the end of the air opening of the intake pipe 3, and a throttle valve 4 and an adjusting screw 5 for adjusting idle, which adjusts an air flow rate when the throttle valve 4 is fully closed, are provided in the middle of the air cleaner. It is arranged. Also, in the intake pipe 3,
Three bypass passages 6, 7, and 8 communicating from the upstream side to the downstream side of the throttle valve 4 are connected. And the first
A bypass adjusting screw 12 that flows through the passage 6 and adjusts the flow rate of the bypass air for idling adjustment is provided in the bypass passage 6, and a bypass valve 14 is provided in the second bypass passage 7, and a third bypass passage 8 is provided in the second bypass passage 7. Is provided with a temperature-sensitive first idle valve 15 that opens only when the engine is cold.

The bypass valve 14 is a valve element 14a that closes the bypass passage 7.
A coil spring 14b that constantly urges the valve element 14a in the closing direction, and a solenoid 14c that opens the valve element 14a against the pressing force of the coil spring 14b when the valve element 14a is urged. The solenoid 14c of the bypass valve 14 is connected to the electronic control unit 10. The duty of the bypass valve 14 is controlled by a drive signal from the control device 10, and the bypass valve 14 controls the idle flow rate by adjusting the flow rate of the bypass air flowing through the bypass passage 7. The amount of operation of the bypass valve 14 that is duty-controlled is defined by the duty ratio D, and bypass air corresponding to the duty ratio D is supplied to the engine 1.

For example, a wax-type first idle valve 15 is preferably used, and cooling water for cooling the engine 1 is supplied. The first idle valve 15 is provided with a bypass passage 8 by a valve body 15a that expands and contracts according to the temperature of the cooling water.
When the cooling water temperature is equal to or higher than a predetermined value, the valve body 15a completely closes the bypass passage 8, whereas when the cooling water temperature is equal to or lower than the predetermined value, the bypass passage 8 is opened according to the water temperature, and the amount of bypass air to the engine 1 is increased. The idling speed is increased to stabilize the idling operation in the cold state.

Each cylinder 1a of the engine 1 is provided with a spark plug 9 for igniting the air-fuel mixture in the cylinder 1a. The spark plug 9 is connected to the electronic control unit 10 via a distributor 16, an ignition coil 17, and a drive circuit 18. Connected to the output side. The drive circuit 18 supplies a primary voltage to the ignition coil 17 according to a control signal supplied from the electronic control unit 10, and the ignition coil 17 generates a secondary high voltage when the supply of the primary voltage is stopped.

A fuel injection valve 20 attached to the intake manifold 2 of each cylinder 1a is connected to the output side of the electronic control unit 10,
The valve is opened in response to a valve opening drive signal from the electronic control unit 10, and a required amount of fuel corresponding to the intake air amount is injected and supplied to each cylinder 1a. On the other hand, a changeover switch 11 is connected to the input side of the electronic control unit 10. The changeover switch 11 is a manual switch for performing idle adjustment of the engine 1, and includes a changeover contact piece 11a having one end grounded and a contact 11b. The changeover switch 11 is provided, for example, on the housing of the electronic control unit 10 and the like.
When a is switched to the contact 11b side, an ON signal as a command signal for fixing the bypass air flow rate and the ignition timing to predetermined values is generated and supplied to the electronic control unit 10.

Next, the operation of the idle speed adjusting device configured as described above will be described below.

FIG. 2 is a flowchart of an idle adjustment routine showing a control procedure executed by the electronic control device 10 of the idle speed adjustment device shown in FIG.

First, the electronic control unit 10 determines whether or not the changeover switch 11 is turned on and an ON signal for starting idle adjustment is input (step 20). If the result of this determination is negative (No), the electronic control unit 10 proceeds to step 22 and
Normal ignition timing control in normal mode and bypass valve 14
Is performed.

The duty control of the bypass valve 14 in the normal mode is performed, for example, as follows. The electronic control unit 10 includes an engine speed sensor (not shown), an engine water temperature sensor,
Detecting an operating condition of the engine by the air conditioner switch or the like, and sets the target idle speed N _eo, the deviation between the target idle speed N _eo and the actual engine speed N _e delta
N (= N _e −N _eo ) is calculated, and the duty ratio D according to the calculated deviation ΔN is set. On the other hand, the ignition timing T _IG is also set according to the detected engine operating condition. Then, the electronic control unit 10 is thus computed based on the duty ratio D and the ignition timing T _IG, and controls the operation of the bypass valve 14 and the drive circuit (power transistor circuit) 18, the target engine speed N _e Stabilize near idle speed _Neo .

Next, after confirming that the engine 1 has been warmed up and that the engine is in a stable idling operation state such as the first idle valve 15 being fully closed, the mechanic performs an idle adjustment and an ignition timing adjustment. When the changeover switch 11 is turned on,
The electronic control unit 10 makes an affirmative determination in step 20 due to the input of the ON signal from the switching step S11 (Yes).
Then, steps S24 and S26 are executed to perform the duty control and the ignition timing control of the bypass valve 14 in the adjustment mode. That is, the electronic control unit 10 outputs a predetermined control signal to the drive circuit 18 in step 24, the ignition timing, suitable to do idle adjustment and ignition timing adjustment, a predetermined value IG _O that has been set in advance ( For example, BTDC is fixed to 5 °), and in step S26, the duty ratio D of the bypass valve 14 is set according to the following equation, and the duty of the bypass valve 14 is controlled by the duty ratio D.

D = D _O + ΔD Here, D _O is a constant value, and the duty ratio may be 0%. ΔD is in the normal idling state and, normal idle speed N _ST, is operated at normal spark advance IG _ST, the ignition timing of the idle adjusted engine to a predetermined value IG _O during the above adjustment corresponding to the engine speed change amount that varies when setting a correction value required to maintain the engine speed to the normal idle speed N _ST.

Here, set during idling adjustment, a predetermined ignition timing IG _O described above are normally set to a predetermined value of the normal spark advance IG _ST from the delay angle side in order to stabilize the engine speed during the adjustment . For this reason, the engine speed drops by the amount corresponding to the retarded ignition timing, and ΔD is set to a value that increases the bypass air amount by the number of the rotating speed and keeps the engine speed constant. . Therefore, in the idle adjustment, after fixing the ignition timing and the duty ratio of the bypass valve 14 to the predetermined values as described above, the maintenance person adjusts the engine speed Ne to the standard idle speed N _ST (for example, 800 rpm). Then, the adjustment screw 12 or the adjustment screw 5 may be adjusted. At this time, since the engine speed is stable due to the retardation of the ignition timing and the increase in the bypass air amount corresponding to the duty ratio ΔD, there is no fluctuation in the engine speed, and the adjustment becomes easy.
Further, since the adjustment speed is the same rotational speed as the normal idle speed N _ST, easily remember the adjustment speed becomes difficult mistake take this to other values.

The adjustment of the flow rate of the bypass air flowing through the bypass passage 7 is controlled by the duty ratio of the bypass valve 14. However, the present invention is not limited to this. For example, the flow rate of the bypass air may be adjusted using a pulse motor or a linear solenoid. Good. In this case, the operation amount of the bypass valve is defined by the change amount of the valve body. Adjustment of the bypass air flow rate is performed by the above bypass valve.
Alternatively, the throttle valve may be forcibly opened and closed near the fully closed position of the throttle valve.

As described above in detail (Effect of the Invention) According to the idling rotational speed adjusting device for an internal combustion engine of the present invention, at the time of idling adjustment, and set to a predetermined value different from the ignition timing to the normal spark advance IG _ST, this After correcting the bypass air amount by the amount corresponding to the rotation speed change amount changed by the ignition timing change setting, the idle speed adjustment means is adjusted so that the engine speed matches the normal idle speed. The engine speed can be stabilized, the adjustment is easy, and the adjustment speed is the same as the normal idle speed. Therefore, it is easy to remember the adjustment speed, and it is difficult to mistake it for another speed value. Has the effect of

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an idle speed adjusting device for implementing the method of the present invention, FIG. 2 is a flowchart showing a control procedure executed by an electronic control unit 10 shown in FIG. 1, and FIG. 4 is a graph for explaining an operation line of an engine speed that changes with a change in time. DESCRIPTION OF SYMBOLS 1 ... Engine, 4 ... Throttle valve, 5 ... Adjust screw (idle adjusting means), 6, 7 ... Bypass passage, 9 ... Spark plug, 10 ... Electronic control device, 11 ... Changeover switch, 12 ... bypass adjusting screw (idle adjusting means), 14 ... bypass valve, solenoid valve (bypass valve), 15 ... control device, 18 ... drive circuit.

Claims (1)

(57) [Claims] 1. An idler which is provided with a bypass valve in a bypass passage which bypasses a throttle valve provided in an intake passage, and adjusts an intake air amount when the throttle valve and the bypass valve are fully closed by a manual operation. Equipped with adjustment means,
During idle operation in which the throttle valve is fully closed, the intake air amount is adjusted by the bypass valve to control the engine speed near the target idle speed, while adjusting the intake air amount by the idle adjustment means during idle adjustment. In the idle adjustment method for an internal combustion engine in which the ignition timing and the engine speed in the standard idle operation state are to be controlled to the normal ignition advance and the normal idle speed, respectively, the ignition timing is set to the normal ignition advance in idle adjustment. After fixing the operation amount of the bypass valve to a predetermined value corresponding to the amount of change in the number of revolutions that changes when the ignition timing is changed from the normal ignition advance to the predetermined value, the engine speed is fixed. Adjusting the idle adjusting means so that the engine speed matches the normal idle speed. Dollar adjustment method.