JPS6254983B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for controlling engine speed. For example, in an automobile engine, it is important to maintain the engine speed at a predetermined constant value under idling conditions. This predetermined constant value is a minimum value that does not cause the rotation of the engine to stop. Incidentally, modern automobiles are equipped with various auxiliary devices such as car coolers, power steering, etc., and the driving of these devices causes various load fluctuations to be applied to the engine during idling. In this case, it goes without saying that the predetermined constant engine speed must be quickly restored no matter what load fluctuation occurs. For this reason, a normal control method is to apply feedback control to the engine in response to the load fluctuations. or,
An open-loop control method in which a predetermined fixed correction is applied externally depending on conditions is also a common control method. However, the above-described conventional control method often has the disadvantage that high-quality engine speed control cannot be ensured. For example, in the case of the above-mentioned feedback control, so-called hunting occurs in response to sudden load fluctuations, which is disadvantageous in that responsiveness eventually deteriorates. Further, according to the open loop control described above, depending on the degree of the correction amount applied from the outside, the system becomes stable when it slightly deviates from the target value (a predetermined constant engine speed), resulting in a disadvantage that the accuracy of reaching the target value deteriorates. It is. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to propose a method for controlling engine rotation speed that does not cause the above-mentioned disadvantages, that is, has good responsiveness and high precision in reaching a target value. In accordance with the above object, the present invention includes: a first step of calculating a difference between a target value of engine speed and a current value of engine speed; a second step of setting a deviation amount corresponding to the difference; and a second step of setting a deviation amount corresponding to the difference amount. a third step of generating a deviation correction amount; and a fourth step of controlling the drive system of the engine according to the deviation correction amount to guide the engine speed to the target value. In the control method, a fifth step exists in parallel with the third step, and generates a deviation correction amount that increases or decreases over time in response to the deviation amount, and adds this to the fourth step; Exists in parallel with the second step and the third step,
Further, a series process consisting of a sixth step of detecting the acceleration of the change in the difference and a seventh step of generating an acceleration correction amount corresponding to the acceleration and adding it to the fourth step, In the third step, when the deviation amount is within a predetermined range, a correction amount proportional to the deviation amount is generated as the deviation correction amount, while when it is outside the range, a correction amount proportional to the deviation amount is generated. A constant correction amount corresponding to an upper limit or a lower limit value is generated as the deviation correction amount, and in the seventh step, when the acceleration is within a predetermined range, a correction amount proportional to the acceleration is generated as the deviation correction amount. The acceleration correction amount is generated as an acceleration correction amount, and when the acceleration correction amount is outside the range, a constant correction amount corresponding to the upper or lower limit value of the range is generated as the acceleration correction amount. The present invention will be explained below with reference to the drawings. FIG. 1 is a flow diagram for explaining the method of the present invention. In this diagram, the rightmost 10
is the engine to be controlled. First, in the first step, the rotation speed R of the engine 10 is applied to the (-) terminal of the adder 1, while a constant target value D of the rotation speed of the engine 10 is applied to the (+) terminal thereof. , the difference between the two is taken. As a second step, this difference is converted into a deviation amount corresponding to the difference in the deviation generating section 2. In the third step, a deviation correction amount corresponding to the deviation amount is generated by the deviation correction generation section 3. In the fourth step, the correction amount calculation section 8 and the throttle drive section 9 are controlled according to the deviation correction amount to guide the rotation speed of the engine 10 to the target value. The first to fourth steps described above are employed in a well-known general automatic control loop. However, with only these existing steps, there are drawbacks to the aforementioned target value attainment accuracy and responsiveness, so the generation section 3 will be modified and several new steps will be added. However, both processes
In principle, the so-called P (Proportional) operation, I
This is known as the (lntegration) operation or the D (differential) operation. First, looking at the deviation correction generating section 3, the method of correction is as shown in FIG. The graph in FIG. 2 shows the deviation amount d from the generation unit 2 (FIG. 1) on the horizontal axis, and the deviation correction amount C1 on the vertical axis. As is clear from this graph, the amount of deviation is within the predetermined range W1
When the value within the range changes from zero to the +d or -d side, the deviation correction amount C1 to be generated is proportional to the deviation amount d.
However, when the deviation amount d becomes excessive and falls outside the range W1, no further correction is made and the deviation correction amount d is suppressed to a constant deviation correction amount C1max or C1min. As a result, it is possible to suppress the so-called hunting phenomenon that tends to occur when excessive deviation correction is applied. However, since excessive deviation correction should have been added, it was suppressed to a constant value, so it is necessary to compensate in some way. For this purpose, the deviation correction generation section 5 is added. What should be noted here is that the generation section 5 plays another important role. That is, its role is to reduce errors in reaching the target value that occur due to the so-called hysteresis phenomenon that often accompanies feedback control. The graph in FIG. 3 is for explaining the hysteresis phenomenon. In this figure, the horizontal axis shows the control amount V for the engine 10, and the vertical axis shows the variation amount T at that time. The loop indicated by the arrow in this graph is a so-called hysteresis, and for example, in order to obtain the same variation amount t, the control amount on the forward path and the control amount on the return path must be different by ν _a and ν _b , respectively. However, if this is ignored, a certain error will be inherent in the target value. The generation unit 5 is also important as a function to bring this inherent error to zero. The deviation correction amount thus obtained is input to the adder 4-1 in FIG. 1, and the amount is taken into account by the correction amount calculation section 8 in FIG. The above-described steps are illustrated as shown in A, B, and C in FIG. 4. A in FIG. 4 shows the relationship between the engine speed R and the elapsed time, and B in FIG. 4 shows the relationship between the correction amount C1 from the deviation correction generator 3 in FIG. , FIG. 1C shows the relationship of the correction amount C2 from the deviation correction generation unit 5 of FIG. 1 with respect to the elapsed time. In the same figure A, D is the target value already mentioned (see Figure 1), and the width W of the upper and lower limit values shown by the dashed-dotted lines above and below corresponds to the range W1 in Figure 2. . When the rotational speed R is outside the range W1 (see dotted line a' in FIG. 4A), the deviation correction generator 3
The correction amount C1 is a constant value of C1max (see solid line b in Figure B). Further, when the rotation speed R falls within the range W1, the correction amount C1 changes in proportion to the deviation amount (the dotted line in the figure B).
c′). Eventually, it stabilizes at a constant value. However, the routes indicated by the dotted lines in FIGS. 4A and 4B are not true control, but include the hysteresis factor explained in FIG. 3. The control error caused by this hysteresis factor is corrected by the correction amount C2 (see C in FIG. 4) that increases and decreases over time in the deviation correction generation unit 5 in FIG. Solid line routes a and c are obtained, and reaching the true target value D is guaranteed. Also, this correction amount C2
However, as described above, the correction amount is simultaneously compensated for by the constant correction amount C1max suppressed to prevent hunting. In this way, control with good target value attainment accuracy and good responsiveness is achieved to some extent. A certain degree means that stability factors have not yet been sufficiently considered in the above steps. In order to ensure this stability, the acceleration of the engine rotation speed R is monitored and control corresponding to this is also taken into consideration. In other words, if an attempt is made to sensitively follow a sudden change in the engine speed R, an excessive deviation correction will be suddenly applied to the correction amount calculation section 8 in FIG. 1, which will also cause hunting or overshoot. This will result in a worsening of stability. Therefore, the change in the difference amount (that is, acceleration) from the adder 1 in FIG. 1 is detected by the acceleration detection section 6 in FIG. 1, and based on this, the acceleration correction amount C3 is is generated and added to the (-) terminal of adder 4-2 in FIG. FIG. 5 is a graph showing the relationship between acceleration α and the acceleration correction amount C3.
When changing to +α or -α, the correction amount C3 is proportional to the change. However, when the acceleration α is outside the range W3, it is suppressed to a constant value C3max or C3min. The correction amount C3 is C3max~C
3 min, the stability is sufficiently ensured, but the correction amount C3 (C3
This is because, if C3max or C3<C3min) is added, the responsiveness will be inhibited. The table below is a list showing the correction direction of the correction operation described above.

[Table] In the table above, target value D of engine speed
When the deviation d(D-R) between the current value R and the current value R is insufficient (+), the deviation correction generating units 3 and 5 shown in FIG. 1 operate to apply correction to the positive side (+). At this time, the acceleration correction generation unit 7 generates (+) of the deviation d,
It has nothing to do with (-). Similarly deviation (DR)
is over (-), the generators 3 and 5
The correction amount operates to add correction to the negative side (-). On the other hand, regarding the magnitude of acceleration α, if it is a positive acceleration (+), the correction is applied to the negative side (-), and if it is a negative acceleration (-), it is corrected to the positive side (+). Each operates to add correction.
In this case, the generators 3 and 5 are unrelated to the acceleration α. As described above, according to the present invention, an engine control method with good target value attainment accuracy, good responsiveness, and excellent stability can be realized.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram for explaining the method of the present invention, FIG. 2 is a graph for explaining the operation of the deviation correction generator 3, FIG. 3 is a graph for explaining the so-called hysteresis phenomenon, and FIG. 4 is a graph for explaining the so-called hysteresis phenomenon. Graphs A, B, and C in the figure are used to explain the operation of the deviation correction generation units 3 and 5 in the present invention, and FIG. 5 is a graph used to explain the operation of the acceleration deviation generation unit 7. In the figure, 1, 4-1, and 4-2 are adders, 2 is a deviation generation section, 3 is a deviation correction generation section, and 5
6 is a deviation correction generation section, 6 is an acceleration detection section, 7 is an acceleration correction generation section, 10 is an engine, R is an engine rotation speed, and D is a target value of the engine rotation speed.

Claims (1)

[Claims] 1. A first step of calculating a difference between a target value of engine speed and a current value of engine speed; a second step of setting a deviation amount corresponding to the difference; and a second step of setting a deviation amount corresponding to the difference amount. a third step of generating a deviation correction amount; and a fourth step of controlling the drive system of the engine according to the deviation correction amount to guide the engine speed to the target value. In the control method, a fifth step exists in parallel with the third step, and generates a deviation correction amount that increases or decreases over time in response to the deviation amount, and adds this to the fourth step; Exists in parallel with the second step and the third step,
Further, a series process consisting of a sixth step of detecting the acceleration of the change in the difference and a seventh step of generating an acceleration correction amount corresponding to the acceleration and adding it to the fourth step, In the third step, when the deviation amount is within a predetermined range, a correction amount proportional to the deviation amount is generated as the deviation correction amount, while when it is outside the range, a correction amount proportional to the deviation amount is generated. A constant correction amount corresponding to an upper limit or a lower limit value is generated as the deviation correction amount, and in the seventh step, when the acceleration is within a predetermined range, a correction amount proportional to the acceleration is generated as the deviation correction amount. A method for controlling engine rotation speed, characterized in that the acceleration correction amount is generated as an acceleration correction amount, and when the acceleration correction amount is outside the range, a certain correction amount corresponding to an upper limit or a lower limit value of the range is generated as the acceleration correction amount. .