JPH0534497B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A) Technical field The present invention provides a system for controlling the rotational speed of an internal combustion engine, more specifically, a controller preferably having PI or PID operating characteristics, so that the actual rotational speed is kept at a predetermined value. The present invention relates to a rotation speed control device for an internal combustion engine, which increases a target value of the rotation speed, especially during idling.

B) Prior art For example, Japanese Patent Application Laid-Open No. 58-20931 discloses a method for controlling the rotation speed during idling by increasing the target value when the actual value of the rotation speed becomes a predetermined distance from the target value of the rotation speed. A method is disclosed. In this method, the setpoint value of the rotational speed is adjusted so that the distance from the actual rotational speed value is constant, and the adjustment is continued until the setpoint value of the rotational speed reaches a predetermined value.

It has been found that such conventional rotational speed control devices cannot necessarily operate optimally under all driving conditions. This is because the engine may enter idling control due to shaking vibration (low-frequency jump or shaking phenomenon) at the rotational speed in a region where the target rotational speed value increases.

C) Purpose Therefore, the present invention has been made to eliminate such conventional drawbacks, and it operates optimally in all drive ranges and maintains idle rotation even when rotational speed fluctuations (shaking vibrations) occur. An object of the present invention is to provide a rotation speed control device for an internal combustion engine that can prevent rotation speed control from reaching a numerical target value.

In order to achieve this object, the present invention provides a rotation speed control device for an internal combustion engine that controls the rotation speed of the internal combustion engine during idling or when transitioning to idling operation. a regulator for controlling the rotational speed according to the deviation; and means for increasing an idling rotational speed target value as the rotational speed increases from a predetermined actual rotational speed value; A configuration was adopted in which the gap between the target rotational speed value and the actual rotational speed value increases linearly as the rotational speed increases.

D) Examples The present invention will be described in detail below according to examples shown in the drawings.

In Figure 1, the rotation speed is the predetermined idle speed.
A state in which the speed increases from NLL and decreases to this idle speed is illustrated with respect to time, and at the same time, a state in which the target value NS of the idle speed (indicated by a dashed line) changes accordingly is shown in the figure. has been done. The speed control device according to the invention is independent of the type of internal combustion engine and can therefore also be applied to gasoline or diesel engines.

As is clear from Fig. 1, the target value NS is corrected according to the actual value DR of the rotation speed, and in that case, the target value is changed sequentially after the gap between the target value and the actual value of the rotation speed reaches a predetermined value. Increased. In the embodiment according to the invention, the gap between this actual value and the target value is NA2
is NLL=700min ^-1 _. , NA21=100min ^-1 _. , NA22=
As 400min ^-1 NA2=(DR−NLL)・NA22/1000min ^-1 +
NA21...determined according to the formula (1). When the target value reaches a predetermined value, for example the maximum value of NB=1400/min, the target value is held constant until the rotational speed decreases and the gap reaches, for example, NA1=50/min. . When this NA1 gap is reached, the target value decreases according to a predetermined function. In this embodiment, the function is an exponential function, but is not limited thereto, and may be a linear, nonlinear, or step-like function.

By changing the gap between the actual value of the rotation speed and the target value according to the rotation speed, it is possible to prevent fluctuations or shaking vibrations in the rotation speed that appear as a noticeable effect when the rotation speed is large in the portion where the target value increases. becomes possible.

Figure 2 shows the difference between the actual value and target value of rotation speed.
NA2 and target value NSM (target value NS in Figure 1 is
20 bits (NSM the upper 10 bits) are plotted for the actual value DR of the rotational speed. From the same figure, the distance NA2 is according to the above formula (1),
Also, for the target value, the idle speed NLL (700/
minutes), it starts to change, and NSM=DR−
NA2...increases according to the formula (2), and then is held at a constant value when the target value reaches NB (1400 revolutions/minute in this embodiment).

The rotational speed control device according to the present invention is preferably implemented using a computer. Next, the flow of the program will be explained with reference to FIG.

The program begins with decision step 10,
This is followed by two calculation steps 11, 12 and three decision steps 13, 14, 15.
This is followed by calculation step 16 and judgment step 17.
This is followed by step 18. Step 18 is led via common line 19 to differential forming step 20 and then
It is led to a PI or PID regulator (regulator with proportional (I), integral (D) or differential (D) action) 21. The other branch lines of decision step 10 are connected to common line 1 via flag setting step 23 and step 24.
Guided by 9. Further, other branch lines of decision steps 15 and 17 are led to this common line 19. A flag set step 26 and a calculation step 27 are arranged between the other branches of the decision step 14 and the common line 19. The other branch lines of the flag decision step 13 are led to a decision step 28, the first branch of which is connected to the common line 19 via a calculation step 29, and the other branch lines are connected to the flag set step 30, a calculation step 31, decision step 32 and step 33, the same is led to the common line 19. Since the functions of each block are illustrated in the drawings, a detailed explanation thereof will be omitted here.

If in step 10 the actual value DR of the rotation speed has not yet reached the minimum rotation value NST (for example 300/min), a flag is set to 0 in step 23 and then in step 24 the setpoint value of the idle speed is set. For example, the idle speed of NSM is 700 rpm
Set to NLL. Subsequently, when the rotational speed DR becomes larger than the minimum rotational speed NST, the difference DN between the actual value DR and the target value NSM is calculated in step 11. In that case, if it becomes negative, DN is set to 0. Subsequently, in a calculation step 12, the rotational speed-related difference between the setpoint value and the actual value is calculated (see above-mentioned equation (1) and line NA2 in FIG. 2).

At the beginning of running, the flag determined in step 13 is set to 0, and the target rotational speed value NSM is equal to, for example, 700/min. As a result, judgments are made in both judgment steps 14 and 15.
In normal driving, the threshold value NA1 = 50 revolutions/min, which is the reference for the reduction in revolutions, is passed very quickly.
Furthermore, since the target value of the rotation speed will not be less than 700 rotations/minute (calculation steps 27, 29), if the rotation speed increases, the judgment step 15 is first reached. If the measured rotational speed difference DN is less than the calculated difference NA2 from the target value, the rotational speed target value NSM does not change.

Otherwise, the setpoint value is increased. The setpoint value is then determined by calculating the difference in NA2 of the actual value of the rotational speed (see equation (2)). According to the subsequent decision step 17, this target value is increased until the maximum value NB is reached.

On the other hand, when the number of revolutions decreases as shown in FIG. 1, DN becomes smaller than the value of NA1=50 revolutions per minute, so the decision at decision step 14 becomes a yes branch line. If a reduction in the rotational speed is identified in this way, this is marked by flag=1, as indicated in step 26, and a new rotational speed setpoint value is subsequently calculated. As an example of this, the following formula is used: NS(MSW.LSW) _o+1 =NS _o −K ₁ ·(NS _o −NLL) (3). Subsequently, in step 20, the deviation is determined and control is performed to reach the target value.

Next, when steps 11 and 12 are passed, the value of the flag has changed, so the program shown on the left side of FIG. 3 is valid. If the deviation between the measured value and the setpoint value of the rotational speed is smaller than that calculated in the decreasing section in the example of FIG. 1, a new setpoint value is calculated in step 29; Similarly, control to the target value is performed.

However, if the rotational speed is increased, for example by depressing the accelerator pedal again, the deviation of the measured rotational speed takes on a larger value than the one calculated again. Since there is no need to further reduce the setpoint value, the flag is changed again in step 30, and in step 31 the setpoint value is modified according to the rotational speed until the upper limit NB is reached.

The actual program is created according to this flow, and a microcomputer (Intel 8051) is used as the control device. The computer calculates the desired value of the rotational speed illustrated in FIG. In this case, it is changed according to an exponential function. However, it goes without saying that the gap between the actual value and the target value of the rotational speed is not limited thereto, and can also be varied according to other characteristics. This also applies when reducing the setpoint value of the rotational speed, in which case the reduction characteristic may not only be generally non-linear, but also linear or step-like, for example. Also expression (3)
As can be seen from the figure, it is understandable that the target value of the rotation speed cannot be reduced below NLL = 700 rotations/minute.

By changing the separation NA2 in accordance with the rotational speed in this way, it is possible to prevent the rotational speed control according to the present invention from acting when fluctuations in the rotational speed or shaking vibration occur, and as a result, the fuel supply that cannot be controlled can be prevented. There will be no need to do this. or
By making NA1 smaller than NA2, it is possible to increase the amount of fuel favorably. Another variant of the speed control described above is that the distance between setpoint value and actual value varies not only in relation to speed, but also, for example, in accordance with load and/or temperature. You can also do it. Also, the regulator may be of P action, I action, D action, or a combination of any of these. In this manner, the control device according to the present invention allows various quantities to be combined to obtain optimal results.

E) Effects As explained above, in the present invention, when the idling rotation speed target value increases, the gap between the idling rotation speed target value and the actual rotation speed value increases linearly as the rotation speed increases. Therefore, from a predetermined rotation speed, the idling rotation speed target value is increased by an interval corresponding to the rotation speed even in a low rotation speed region, so when the rotation speed decreases in a low rotation speed region, the idling rotation speed is immediately controlled. This makes it possible to stabilize the rotational speed.

Furthermore, in the present invention, the gap between the target value of idling rotation speed and the actual value of rotation speed increases linearly as the rotation speed increases. Even when fluctuations occur and the rotational speed decreases, the rotational speed is captured by the idling rotational speed target value, thereby preventing the rotational speed from increasing fluctuations. Therefore, even if the rotational speed fluctuates in the high rotational speed region, it is prevented from unnecessarily shifting to idling rotational speed control and exacerbating the rotational speed fluctuation, and stable rotational speed control becomes possible. Various effects can be obtained.

[Brief explanation of drawings]

Each figure shows an embodiment of the present invention.
Figure 1 is a characteristic diagram showing how the target value of rotational speed increases, Figure 2 is a characteristic diagram showing the target value and the gap between this target value and the actual value with respect to rotational speed. FIG. 3 is a flowchart diagram illustrating the flow of control of the present invention. DR, NIST...actual value of rotation speed, NA2...gap between actual value of rotation speed and target value, NLL...idle rotation speed, NSM...target value of rotation speed, NB...upper limit of target value.

Claims (1)

[Claims] 1. In a rotation speed control device for an internal combustion engine that controls the circuit rotation speed of the internal combustion engine during idling or when transitioning to idling operation, according to the deviation between the actual value of the rotation speed and the target value of the idling rotation speed. a regulator 21 for controlling the rotational speed; and means 1 for increasing the idling rotational speed target value as the rotational speed increases from a predetermined actual rotational speed value;
6, 31, wherein when the target idling speed value increases, the gap between the target idling speed value and the actual value of the speed increases linearly as the speed increases. Rotation speed control device. 2 NA2 is the distance, DR is the rotation speed, NLL,
With NA21 and NA22 as constants, NA2=(DR−NLL)・NA22/1000min ^-1 +
2. The rotational speed control device for an internal combustion engine according to claim 1, wherein the distance is determined according to the formula NA21. 3. The rotational speed control device for an internal combustion engine according to claim 1 or 2, wherein the distance is controlled in accordance with load or temperature in addition to the rotational speed. 4. The rotation speed control device for an internal combustion engine according to any one of claims 1 to 3, wherein the maximum value of the idling rotation speed target value is limited to a predetermined value NB. 5. When the rotation speed decreases until the difference between the actual rotation speed value and the increased idling rotation speed target value becomes a predetermined difference NA1, the idling rotation speed target value is reduced as the rotation speed decreases. A rotation speed control device for an internal combustion engine according to any one of claims 1 to 4.