JP2000045797A - Idle rotation controller for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To converge to a changed speed of rotation (target idle speed) without generating the under shoot phenomenon even when the idle speed is manually increased and corrected by using an idle set means. SOLUTION: In an electronic control governor of a diesel engine where PID control of the idle speed is executed by comprising an idle set means for arbitrarily increasing and decreasing the idle speed, and a governor map storing the lower limit value of a rack position corresponding to the 0% accelerator opening, a means for changing the lower limit value of the rack position determined in the governor map corresponding to the setting of the idle set means and outputting the same, is mounted for preventing or inhibiting the under shoot of the rack concerned in the PID control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device for a diesel engine, and more particularly, to an electronic control governor for controlling the idle speed by PID control.
The present invention relates to an idle speed control device that is effective for stabilizing the idle speed at the time of rapid deceleration in a state where the idle speed is corrected to increase.

[0002]

2. Description of the Related Art In an electronic governor control system for a diesel engine in which the idling speed is controlled by PID, for example, as shown in FIG. As shown in the governor map, when the engine is rapidly decelerated from point P, the rack position of the injection pump is changed in advance as P → D → C → A as the engine speed decreases, and the engine speed is reduced. Is converged to the specified idle speed N1. Further, since it is necessary to arbitrarily change the idle speed depending on the use of the engine, idle setting means for arbitrarily adjusting the idle speed may be provided.

However, in the conventional control device, the lower limit value of the rack position read from the governor map is output as it is. For this reason, for example, when the idle speed is set to the target idle speed N2 higher than the specified idle speed N1, this target idle speed N2
Is separated from the lower limit shown by the curve a.

Therefore, when the vehicle is suddenly decelerated from the point P, as shown by a dashed line in FIG. 3, the rack pulling up is started only when the actual engine speed falls below the target idle speed N2. Although an engine stall does not occur, an undershoot phenomenon occurs in which the engine speed falls back to the target idle speed N2 after the engine speed drops below the target idle speed N2, and the reliability of the idle setting means may be impaired. Was.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and does not cause an undershoot phenomenon even when the idle speed is manually corrected to increase by using idle setting means. It is an object to provide an idle rotation control device that can converge to an arbitrary target idle rotation speed.

[0006]

In order to solve the above-mentioned problems, the present invention provides idle setting means for arbitrarily increasing or decreasing the idle speed while setting a lower limit of a rack position corresponding to an accelerator opening of 0%. By providing the stored governor map, in the electronic control governor of the diesel engine in which the idling speed is controlled by PID,
A means for changing and outputting the lower limit value of the rack position defined in the governor map in response to the setting of the idle setting means is provided.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a control characteristic diagram according to an embodiment of an idle rotation control device for a diesel engine according to the present invention. The idle rotation control device according to this embodiment has a lower limit value of a rack position corresponding to an accelerator opening of 0%. It has a governor map storing a. Then, at the time of rapid deceleration from the point P, the PID control for converging the engine speed to the specified idle speed N1 by changing the rack position in advance as P → D → C → A as the engine speed decreases. I do it.

Further, the idle speed control device according to the present embodiment is provided with idle setting means for adjusting the idle speed of the engine to an arbitrary target idle speed N2. In addition, since the electronic governor control device of the diesel engine which is capable of controlling the idling speed by the PID control and adjusting the idling speed to an arbitrary target idling speed N2 is well known in the related art, its detailed description is omitted. Description is omitted.

Here, in this embodiment, the target idle speed N2 set by the idle setting means is set.
The lower limit value a of the rack position defined in the governor map in response to
By sliding, for example, accelerator opening 3%
Is provided as a lower limit value b corresponding to.
When the idle speed is set to an arbitrary target idle speed N2 higher than the specified idle speed N1, the lower limit value a of the rack position set in the governor map corresponding to the specified idle speed N1 is set to: PID control of the idle speed is performed based on the lower limit value b changed to a value corresponding to the target idle speed N2.

Therefore, even when the target idle speed N2 is set to an arbitrary value higher than the specified idle speed N1, the specified idle speed N
In the same manner as in the case 1, the rack position of the injection pump is prevented from being undershooted by changing the rack position in the order of P → E → F → G along the curve shown by the two-dot chain line in FIG.

For this reason, conventionally, as shown by the dashed line in FIG. 2, during rapid deceleration, the rack is pulled up after the actual engine speed falls below the target idle speed N2, and the target idle speed is increased. However, according to the present embodiment, even at the target idle speed N2 set by the idle setting means as described above, the PID control is performed to change the rack position ahead to avoid undershoot. Therefore, the actual rotation speed does not become lower than the target idle rotation speed N2 as shown by the solid line in FIG.

In the embodiment, the accelerator opening 0
% Of the rack position corresponding to the accelerator opening 3%
Is described as the lower limit value b, but the lower limit value b output may be changed according to the degree of idle-up by the idle setting means or the characteristics of the engine. The means for changing and outputting the lower limit value of the rack position can be constituted by, for example, adding an electronic circuit or changing a program.

[0013]

As is apparent from the above description, according to the present invention, the lower limit of the rack position corresponding to the accelerator opening of 0% defined in the governor map is changed and output in response to the setting of the idle setting means. Because it has a means,
Even when the idle speed is adjusted to an arbitrary value,
The undershoot of the rack, which has been concerned in the PID control, can be avoided or suppressed, and the reliability of the idle setting means can be increased.

[Brief description of the drawings]

FIG. 1 is a control characteristic diagram according to an embodiment of an idle rotation control device for a diesel engine according to the present invention.

FIG. 2 is a characteristic diagram showing a change state of an engine speed at the time of sudden deceleration.

FIG. 3 is a control characteristic diagram of a conventional control device.

[Explanation of symbols]

 a Lower limit of rack position corresponding to accelerator opening of 0% b Lower limit of rack position corresponding to accelerator opening of 3% N1 Specified idle speed N2 Target idle speed

Claims (1)

[Claims] An idle setting means for arbitrarily increasing or decreasing the idle speed is provided, and a governor map storing a lower limit value of a rack position corresponding to an accelerator opening of 0% is provided, so that the idle speed can be controlled by PID. An electronically controlled governor for a diesel engine controlled, comprising: a means for changing and outputting a lower limit value of a rack position defined in a governor map in response to a setting of the idle setting means. Idle rotation control device.