JP2775514B2 - Idle speed control device for internal combustion engine for vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an idle speed control device for an internal combustion engine for a vehicle.

<Conventional technology> As an idle speed control device for an internal combustion engine for a vehicle, an auxiliary air control valve is provided in an auxiliary air passage that bypasses a throttle valve, and the actual engine speed and a target idle speed are compared under idle operation conditions. In addition, there is an apparatus in which the opening degree of the auxiliary air control valve is controlled based on the comparison result, and the engine speed is feedback-controlled to the target idle speed (see JP-A-61-118542).

<Problems to be Solved by the Invention> In such an idle speed control device, it is desirable to set a low target idle speed in order to improve fuel efficiency.

However, there is a problem that the target idle speed must be set to a certain high value because feedback control of disturbance such as sudden deceleration from a high-speed region is poor and the engine may stall.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and has as its object to stabilize control at the time of rapid deceleration from a high-speed range and set a low target idle speed.

<Means for Solving the Problems> For this reason, as shown in FIG. 1, the present invention includes an auxiliary air control valve in an auxiliary air passage that bypasses a throttle valve, and performs actual engine rotation under idle operation conditions. The internal combustion engine for a vehicle includes means (feedback control means) for controlling the opening of the auxiliary air control valve based on the comparison result by comparing the engine speed with the target idle speed and performing feedback control of the engine speed to the target idle speed. In the idle speed control device, means for detecting a sudden deceleration based on the running state of the vehicle (sudden deceleration detecting means) and means for setting a reference model of the opening degree of the auxiliary air control valve when the rapid deceleration is detected (the reference model) Setting means) and means for comparing the opening of the auxiliary air control valve by the feedback control and the opening of the reference air control valve with the reference model and issuing a signal when the difference is large (comparative means). And a means (feedforward control means) for stopping the feedback control in response to this signal and for controlling the opening of the auxiliary air control valve in a feedforward manner in accordance with a reference model.

<Operation> In the above configuration, at the time of sudden deceleration from a high speed range,
Feedback control with poor followability is stopped, and feedforward control is performed in accordance with a time-auxiliary air control valve opening degree characteristic based on a predetermined reference model to improve engine stall resistance. This makes it possible to lower the target idle speed.

<Example> An example of the present invention will be described below.

In FIG. 2, air from an air cleaner 1 passes through an intake duct 2 and a throttle valve 3 interlocked with an accelerator pedal (not shown) and an electromagnetic auxiliary air interposed in an auxiliary air passage 4 that bypasses the throttle valve 3. Under the control of the control valve 5, it is sucked. Then, the fuel is mixed with the fuel injected from the fuel injection valve 7 in the intake manifold 6 and is sucked into the engine 8.

The opening of the auxiliary air control valve 5 is controlled by a control signal from the control unit 9, and signals from various sensors are input to the control unit 9 for such control.

As the various sensors, a rotation speed sensor 10 is provided to detect the engine rotation speed N. Further, a water temperature sensor 11 is provided to detect an engine cooling water temperature Tw. Further, a throttle sensor 12 is provided to detect a throttle valve opening TVO. Further, a vehicle speed sensor 13 is provided to detect a vehicle speed VSP. In addition, in the neutral position of the transmission
A neutral switch 14 that is turned on, a brake switch 15 that is turned on when a brake pedal is depressed, and the like are provided.

Here, the microcomputer in the control unit 9 controls the opening of the auxiliary air control valve 5 by performing arithmetic processing based on signals from the various sensors in accordance with the flowchart of FIG.

 The routine shown in FIG. 3 is executed every predetermined time.

In step 1 (indicated as S1 in the figure, the same applies hereinafter), a basic control value ISC _TW (%) is set by searching with reference to a map based on the water temperature Tw detected by the water temperature sensor 11.

In step 2, it is determined whether or not an idling operation condition (idling speed feedback control condition) is satisfied. here,
The idle speed feedback control condition is that the throttle valve is fully closed and in a neutral state, or that the throttle valve is fully closed and the vehicle speed is equal to or lower than a predetermined value.

In the case of the idle speed feedback control condition, feedback control is performed in steps 3 to 6. That is, in step 3, the target idle speed Ns is searched by referring to a map based on the water temperature Tw, and in step 4, the engine speed N detected by the speed sensor 10 is compared with the target idle speed Ns. , N <predetermined integral portion I is increased relative to the previous value of the feedback correction value ISC _CL (%) by the integration control in the step 5 when the Ns, N> feedback correction value by the integral control in step 6 when the Ns ISC
_CL (%) is decreased by a predetermined integral I from the previous value.

In step 7, the valve opening duty ISC is calculated from the basic control value ISC _TW and the feedback correction value ISC _CL according to the following equation.
Calculate _ON (%).

ISC _ON = ISC _TW + ISC _CL Here, steps 1 to 7 correspond to feedback control means.

In the next step 8, it is determined whether or not the vehicle is suddenly decelerated from a high speed range based on the running state such as the vehicle speed VSP and the braking state.
This part corresponds to a sudden deceleration detecting means.

In the case of NO, the process directly proceeds to step 14, and this valve opening duty ISC _ON is output.

 If YES (sudden deceleration), go to step 9.

In step 9, reference is made to a reference model in which the degree of opening (valve opening duty) of the auxiliary air control valve at the time of sudden deceleration is determined by using time as a parameter, and the reference valve is opened according to the elapsed time from the first detection of sudden deceleration. Search for duty ISC _ON ′. This part corresponds to the reference model setting means.

In step 10, it calculates the -ISC _ON 'difference ΔISC = ISC _ON the opening duty ISC _ON by the feedback control and the' norm opening duty ISC _ON, the next step 11,
The difference ΔISC is compared with a predetermined value C. When ΔISC ≧ C (when the difference is large), the process proceeds to step 12. These parts correspond to the comparison means.

In step 12, the reference valve opening duty ISC _ON 'is set to the valve opening duty ISC _ON , and the routine proceeds to step 14, where the valve opening duty ISC _ON = ISC _ON ' is output. That is, the feedback control is stopped, and the feedforward control is performed according to the reference model. This part corresponds to the feedforward control means.

Except for the idle speed feedback control condition,
Proceeding from step 2 to step 13, the valve opening duty IS
Calculates C _ON = ISC _TW + ISC _CL and outputs it in step 14. In this case, the clamped ISC _CL is used.

When the valve opening duty ISC _ON is output in step 14,
The valve opening coil of the auxiliary air control valve 5 is energized by the pulse signal of the valve opening duty ISC _ON , whereby the opening is controlled and a desired auxiliary air flow rate is obtained.

According to such control, the following operation and effect can be obtained as compared with the related art.

Referring to FIG. 4, when the vehicle speed suddenly decelerates from a high speed range and the idle speed feedback control condition is satisfied, according to the conventional feedback control, the opening degree (IS
(C opening degree) suddenly decreases as shown by the solid line in the figure, and undershoots may occur at this time. However, in the case of the present invention, feedforward control is performed according to the reference model as shown by the broken line in the figure. By doing so, the stalling resistance is improved.

<Effects of the Invention> As described above, according to the present invention, the feedback control is stopped at the time of sudden deceleration and the feedforward control is performed according to the reference model, so that the engine stall resistance is improved and the target idle speed is reduced. There is an effect that the fuel consumption can be set and the fuel efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a system diagram showing one embodiment of the present invention, FIG. 3 is a flowchart showing control contents, and FIG. 4 is a diagram showing control characteristics. . 3 ... Throttle valve, 4 ... Auxiliary air passage, 5 ... Auxiliary air control valve, 8 ... Engine, 9 ... Control unit, 10 ... Rotation speed sensor, 11 ... Water temperature sensor, 12 ... Throttle sensor , 13 …… Vehicle speed sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-156229 (JP, A) JP-A-55-160137 (JP, A) JP-A-59-46353 (JP, A) JP-A-61-463 81548 (JP, A) JP-A-60-162027 (JP, A) JP-A-61-118542 (JP, A) JP-A-63-61745 (JP, A) JP-A 1-176727 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F02D 41/16

Claims (1)

(57) [Claims] An auxiliary air control valve is provided in an auxiliary air passage which bypasses a throttle valve, and an actual engine speed and a target idle speed are compared under an idle operating condition, and the auxiliary air control valve is controlled based on a comparison result. An idle speed control device for an internal combustion engine for a vehicle, comprising: means for controlling an opening to feedback-control an engine speed to a target idle speed; a means for detecting a sudden deceleration based on a running state of the vehicle; Means for setting a reference model of the opening degree of the auxiliary air control valve at the time of detection, and means for issuing a signal when the difference between the opening degree of the auxiliary air control valve by the feedback control and the opening degree of the reference model is large. Means for receiving the signal, stopping the feedback control, and feedforward controlling the opening of the auxiliary air control valve in accordance with a reference model. The idle speed control apparatus for an internal combustion engine for a vehicle, characterized by comprising.