JPH0765532B2 - Idle speed control device for internal combustion engine - Google Patents

Description

The present invention relates to an idle speed control device for an internal combustion engine.

<Prior Art> An idle speed control device for an internal combustion engine is disclosed in
As disclosed in Japanese Laid-Open Patent Publication No. 62-129544, an idle control valve is provided in the middle of an auxiliary air passage that bypasses a throttle valve installed in the intake system of an engine, and the amount of auxiliary air is adjusted by this idle control valve. There is one that controls the idle rotation speed.

The idle control valve includes, for example, a valve opening coil and a valve closing coil, and energization pulse signals (driving pulse signals) are sent to these coils in mutually inverted states. The opening is adjusted according to the duty ratio of the signal.

The duty ratio of the pulse signal is determined by the control value ISCdy calculated by the following equation, for example. The unit of this control value ISCdy is represented by%, and is output as the time ratio in which the valve opening coil is ON.

ISCdy ＝ ISCtw ＋ ISCet ＋ ISCfd where ISCtw is the basic control value depending on the engine coolant temperature, ISCet
Is various correction amounts such as acceleration / deceleration correction, and ISCfd is a feedback correction amount for feedback control of idle rotation speed, which will be described later.

In the idle speed feedback control, the target idle speed that depends on the engine temperature, which is represented by the coolant temperature, is compared with the actual speed detected by the rotation angle signal from the crank angle sensor. When the rotation speed of is above or below the target, the control value at that time is adjusted to increase or decrease and the control is performed so as to reach the target idle rotation speed. Therefore, the above-mentioned feedback correction amount ISCfd Has been set.

Then, the value of the feedback correction amount ISCfd is changed by the integral control or the proportional-plus-integral control to make the control stable. That is, the target idle rotation speed is compared with the actual rotation speed, and if the actual rotation speed is lower (higher) than the target idle rotation speed, the feedback correction amount ISCfd is increased by a small amount (integration constant) ( Decrease).

However, the feedback control of the idle rotation speed by the feedback correction amount ISCfd is performed when predetermined conditions are met, that is, in a predetermined idle operation state.
The predetermined condition is, for example, when the throttle valve is in the fully closed position (idle position) and the transmission is in the neutral state, or when the throttle valve is in the fully closed position and the vehicle speed is equal to or lower than a predetermined speed (for example, 8 km / h). .

<Problems to be Solved by the Invention> By the way, for example, when the vehicle speed is used as the feedback control condition, the feedback control condition is satisfied by idle traveling, and the electric load, the hydraulic pump for power steering, the compressor for the air conditioner are still in such a state. When the external load such as, for example, is increased and the brake is applied to increase the external load, the external load is increased by the brake load as compared with the feedback control of the general idle speed, so the engine speed becomes the target idle speed. The feedback correction amount ISCfd is increased more than usual so that the control value ISCdy is increased and corrected by this feedback correction amount ISCfd. However, the control value ISCdy is limited to the maximum value (for example, 85%) which is the control limit of the control unit that sends the drive pulse signal to the idle control valve.

In this way, the control value I is adjusted by the feedback correction amount ISCfd.
When the feedback control condition is canceled and the feedback control is not performed after the SCdy is largely increased and corrected, the feedback correction amount ISCfd holds the final value of the feedback control. Due to the addition of the feedback correction amount ISCfd that is set to a large value as described above, the engine rotation speed may jump up due to the excessive supply of the auxiliary air amount, as shown in FIG.

That is, the maximum value of the conventional control value ISCdy (the limit value on the open control side) is regulated in a state where the opening degree of the idle control valve is increased and corrected to compensate for the decrease in the idle rotation speed due to the increase in the external load. However, the maximum value depends on the control capacity of the control unit, and the opening of the idle control valve at the maximum value assists to secure the required auxiliary air amount in anticipation of an increase in external load during cooling. The effective opening area of the air passage is set. Therefore, at the time of complete warming up, it should be possible to supply the auxiliary air amount corresponding to the increase of the external load with the control value ISCdy which is smaller than the above-mentioned maximum value. There is an increase in external load, which is different from
In order to compensate for such an increase in external load, correction by the feedback correction amount ISCfd is performed up to the maximum value,
If the normal external load state is satisfied when the feedback control conditions are satisfied again, an extra auxiliary air amount is to be supplied.

The present invention has been made in view of the above problems, and it is possible to prevent an excessive duty ratio from being set on the open side due to feedback correction, and to prevent the rotation speed from jumping up when the feedback control is restarted. It is an object to provide a rotation speed control device.

<Means for Solving the Problem> Therefore, in the present invention, as shown in FIG. 1, the valve opening duty ratio of the drive pulse signal which is provided in the auxiliary air passage bypassing the throttle valve provided in the intake system of the engine is provided. An idle control valve whose opening is adjusted in accordance with the engine rotation speed detection means for detecting the engine rotation speed, and an engine rotation speed detected by the engine rotation speed detection means under a predetermined idle operating condition. Idle rotation feedback means for setting the feedback correction of the duty ratio so as to approach the rotation speed, engine temperature detection means for detecting the engine temperature, and engine operating conditions including at least the engine temperature detected by the engine temperature detection means. Feed-forward amount setting means for setting the feed-forward amount of the duty ratio based on A duty ratio calculating means for calculating the duty ratio by adding the feed forward amount, and a limit value setting means for variably setting the open side control limit value of the duty ratio according to the engine temperature detected by the engine temperature detecting means. And, when the duty ratio calculated by the duty ratio calculating means exceeds the open side control limit value set by the limit value setting means, while limiting the duty ratio to the open side control limit value, Duty ratio limiting means for updating and setting a value obtained by subtracting the feedforward amount from the open side control limit value as the feedback correction amount, and storing and holding the feedback correction amount when the feedback control by the idle rotation feedback means is stopped. , The initial value of the feedback correction amount stored and retained when the feedback control is restarted A feedback correction amount initial setting means for setting as to constitute comprise idle speed control device and a driving pulse signal output means for outputting a driving pulse signal of the duty ratio to the idle control valve.

<Operation> According to the idle rotation speed control device having such a configuration, in order to obtain the valve opening control duty ratio of the idle control valve for the feed forward set based on the engine operating conditions including the engine temperature and the target idle rotation speed. Set as an addition value with the feedback correction amount of. Here, the open side control limit value of the duty ratio is set according to the engine temperature, and the duty ratio is limited within the open side control limit value. Update and set the feed-forward amount as the feedback correction amount. On the other hand, the feedback correction amount when the feedback control of the idle speed is stopped is stored and held, and when the control is restarted, the feedback control is restarted using the stored value as the initial value of the feedback correction amount. .

<Examples> Examples of the present invention will be described below with reference to the drawings.

In FIG. 2, the air from the air cleaner 1 passes through an intake duct 2, and a throttle valve 3 interlocked with an accelerator pedal (not shown) and an electromagnetic idle control provided in an auxiliary air passage 4 bypassing the throttle valve 3. It is sucked into the engine 8 under the control of the valve (auxiliary air amount control valve) 5. Then, it 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 idle control valve 5 includes a valve opening coil and a valve closing coil, and a drive pulse signal (energization pulse signal) from a control unit 9 including a microcomputer.
Are sent to each of these coils in an inverted state, and the opening degree is controlled by the duty ratio DUTY of the drive pulse signal (time ratio% of the valve opening drive pulse signal). For such control, signals from various sensors are input to the control unit 9.

As the various sensors, a rotation speed sensor 10 as an engine rotation speed detecting means such as a crank angle sensor is provided to detect the engine rotation speed N. Also, the throttle valve 3
An idle switch 11 that is turned on at the idle position is attached to the. Furthermore, the cooling water temperature Tw that represents the engine temperature
A water temperature sensor 12 as an engine temperature detecting means for detecting the temperature is provided in the water jacket portion and outputs a voltage signal according to the cooling water temperature Tw. Further, a vehicle speed sensor 13 for detecting the speed of the vehicle equipped with the engine 8 is provided.

Here, the control unit 9 sets a control value ISCdy that determines the duty ratio DUTY of the drive pulse signal to the idle control valve 5 according to the engine operating state according to the flowchart of FIG. 3 based on the signals from the various sensors. Set.

In the present embodiment, the control unit 9 includes drive pulse signal output means, duty ratio calculation means, idle rotation feedback means, feed forward amount setting means, duty ratio limiting means, limit value setting means, feedback correction amount initial setting means. It doubles as well.

First, in step 1, detection signals are read from various sensors.

Then, in step 2, the basic control value ISCtw (for feed forward) depending on the engine cooling water temperature is set based on the cooling water temperature signal Tw from the water temperature sensor 12 read in step 1.

In the next step 3, various correction amounts ISCet (for feed forward) according to acceleration / deceleration correction, air conditioner, gear position, etc. are set.

In step 4, it is determined whether or not a condition for feedback controlling the engine speed N to the target idle speed N is satisfied. The feedback control condition is, for example, that the idle switch 11 is ON (the throttle valve 3 is in the idle position) and the vehicle speed detected by the vehicle speed sensor 13 is equal to or lower than a predetermined speed (for example, 8 km / h), and the feedback control condition is satisfied. If so, the process proceeds to step 5.

In step 5, a feedback correction amount ISCfb for feedback controlling the actual engine speed N detected by the speed sensor 10 to the target idle speed N
Set (feedback correction amount). Specifically, the target idle rotation speed set according to the cooling water temperature Tw detected by the water temperature sensor 12 and the engine rotation speed N detected by the rotation speed sensor 10 are compared to determine the actual rotation speed N as the target. If it is above (below), the feedback correction amount ISCfb is decreased (increased) by a predetermined integral amount.

Then, in the next step 6, the control value ISCdy is calculated according to the following equation using the setting results in steps 2, 3 and 5.

ISCdy ← ISCtw ＋ ISCet ＋ ISCfb In step 7, based on the cooling water temperature Tw detected by the water temperature sensor 12, the allowable maximum value ISCmax of the control value ISCdy is calculated.
Search for (Kan side control limit value) from the map. This allowable maximum value ISCmaxb is the required auxiliary air amount in the state where no external load such as an electric load or an air conditioner is applied (the control value ISCdy corresponding to this required auxiliary air amount is indicated by a dotted line in the graph in the flowchart of FIG. 3). This is set in anticipation of the addition request value when a predicted total external load such as an air conditioner or electric load is added, and the difference in the requested amount due to the engine temperature is represented by the engine temperature. The cooling water temperature Tw allocation is made possible.
In addition, the maximum value of the allowable maximum value ISCmax on the extremely low temperature side is set to the control limit value of the control unit 9 (for example, 85%), and the control limit value of the control unit 9 of the control value ISCdy at the time of extremely constant temperature is set. The maximum is limited.

When the allowable maximum value ISCmax of the control value ISCdy is obtained in step 7, the control value IS calculated in step 6 is calculated in the next step 8.
Cdy is compared with the allowable maximum value ISCmax to determine whether the control value ISCdy calculated in step 6 exceeds the allowable maximum value ISCmax.

Here, when it is determined that ISCdy> ISCmax,
Since it is larger than the allowable value, the process proceeds to step 9 to set the control value ISCdy this time to the allowable maximum value ISCmax, and the feedback correction amount ISCfb is limited by the allowable maximum value ISCmax, that is, ISCfb ← ISCmax- ISCtw-ISCet.

On the other hand, if it is determined that ISCdy ≦ ISCmax, the calculation result in step 6 is smaller than the allowable value, so that it is not necessary to add a limitation, and therefore step 9 is skipped and the process proceeds to step 13.

In step 13, the drive pulse signal having the duty ratio DUTY corresponding to the control value ISCdy is output to the idle control valve 5, so that the idle control valve 5 is adjusted to the opening degree corresponding to the control value ISCdy, and the auxiliary air passage The amount of auxiliary air supplied to the engine 8 via 4 is controlled.

In this way, the maximum allowable value ISCmax corresponding to the cooling water temperature Tw
If the control value ISCdy and the feedback correction amount ISCfb are limited by, the filter can be adjusted when an external load larger than the normal external load such as an air conditioner or an electric load is applied, such as when the brake is applied in the idle self-propelled state. It is possible to prevent the duck correction amount ISCfb from excessively increasing by following the decrease in the rotation speed N in the external load state larger than usual. Therefore, as described above, the feedback control is stopped from the state in which the feedback control is performed under an external load state larger than usual, the feedback correction amount ISCfb is held as the initial value, and the held feedback correction amount is resumed when the feedback control is restarted. ISCf
Even if b is added to the control value ISCdy, the jump of rotation can be suppressed.

The allowable maximum value ISCmax is set so that the required auxiliary air amount can be secured when a normal external load such as an electric load or an air conditioner is applied.
By limiting the maximum allowable value ISCmax, the required amount of supplementary air will not be lost.

On the other hand, if it is determined in step 4 that the condition for feedback controlling the idle rotation speed to the target rotation speed is not satisfied, the process proceeds to step 10.

In step 10, it is determined whether or not the feedback control condition non-satisfaction determination is the first time. If it is the first time, the process proceeds to step 11 and the feedback correction amount ISCfb previously set in step 5 is used for use when the feedback control is restarted. After storing, proceed to step 12. However,
The control value ISCdy is the maximum allowable value ISCma during feedback control.
If it is limited by x, I set in step 9
SCfb ← ISCmax−ISCtw−ISCet Feedback correction amount
ISCfb will be stored.

In step 12, the control value ISCdy is calculated according to the following equation using the setting results in steps 2 and 3.

ISCdy ← ISCtw + ISCet Then, in the next step 13, the drive pulse signal of the duty ratio DUTY corresponding to the control value ISCdy not including the feedback correction amount ISCfb is output to the idle control valve 5 as described above.

A correction amount set depending on the battery voltage may be added as a component of the control value ISCdy.

Further, even if the feedback control condition is not satisfied, the set control value ISCdy and the allowable maximum value ISCmax may be compared, but the feedback correction amount ISCfb
Since the control value ISCdy does not exceed the maximum allowable value ISCmax in the state where is not included (in other words, ISCtw + ISCet is set to be sufficiently smaller than the limit value to enable feedback correction). In this embodiment, the maximum allowable value ISCmax is limited only when the feedback control condition is satisfied.

<Effects of the Invention> As described above, according to the present invention, in the idle speed control device provided with the idle control valve whose opening is adjusted according to the valve closing duty ratio of the drive pulse signal, the idle speed control device is operated according to the engine temperature. The open side control limit value of the duty ratio is variably set, the final duty ratio and the feedback correction amount of the duty ratio are limited based on the limit value, and the limited feedback correction amount is feedback controlled. Since it is given as the initial value when restarting, it is possible to avoid setting an excessive duty ratio on the open side by the feedback correction, and it is possible to suppress the jump of the rotational speed when restarting the feedback control. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention, FIG. 2 is a system schematic view showing an embodiment of the present invention, and FIG. 3 is a duty pulse ratio of a drive pulse signal to an idle control valve in the above embodiment. FIG. 4 is a time chart for explaining the problems in the conventional idle rotation speed control device. 3 ... Throttle valve, 4 ... Auxiliary air passage, 5 ... Idle control valve, 8 ... Engine, 9 ... Control unit, 10 ... Rotation speed sensor, 12 ... Water temperature sensor

Claims (1)

[Claims] 1. An idle control valve, which is provided in an auxiliary air passage that bypasses a throttle valve provided in an intake system of the engine and whose opening is adjusted according to a valve opening duty ratio of a drive pulse signal, and an engine rotation speed. Engine rotation speed detection means for detecting the engine speed, idle rotation feedback means for setting a feedback correction amount of the duty ratio so that the engine rotation speed detected under a predetermined idle operating condition approaches a predetermined target rotation speed, and an engine temperature An engine temperature detecting means for detecting, a feed forward amount setting means for setting a feed forward amount of the duty ratio based on an engine operating condition including at least the engine temperature detected by the engine temperature detecting means, and the feedback correction amount. And duty ratio calculation means for calculating the duty ratio by adding The limit value setting means for variably setting the open side control limit value of the duty ratio according to the engine temperature detected by the engine temperature detecting means, and the duty ratio calculated by the duty ratio calculating means are the limit value setting means. When the open side control limit value set in the above is exceeded, the duty ratio is limited to the open side control limit value, and a value obtained by subtracting the feed forward amount from the open side control limit value is used as the feedback correction amount. The duty ratio limiting means to be updated and set, the feedback correction amount when the feedback control by the idle rotation feedback means is stopped is stored and held, and is set as an initial value of the stored feedback correction amount when the feedback control is restarted. Feedback correction initial setting means and drive pulse signal of the duty ratio The idle speed control apparatus for an internal combustion engine, characterized in that it is configured to include a drive pulse signal output means for outputting to the idle control valve.