JPH04159437A - Engine rotational speed control device - Google Patents

Abstract

PURPOSE:To reduce the time of covergence to an objective rotational speed by changing the PID constant by whether the load variation quantity exceeds a specified range, or not, in the engine control based on a PID arithmetic result on the basis of a deviation between an objective and an actual rotational speed. CONSTITUTION:An actual engine rotational speed is calculated from a pulse signal P transmitted from an engine rotational sensor 4 by an actual rotational speed arithmetic means 5 and the calculation value is inputted to a rotational speed deviation detection means 6 wherein a deviation N from an objective rotational speed transmitted from an objective rotational speed setting means 7 is calculated. Whether the deviation N is within the range of its set value, or not, is determined by a determination means 8. On the basis of the determination result, mutually different PID constants are set by a PID constant setting means 9. Then the position of a control rack 2a is PID-calculated on the basis of the deviation N by a first PID arithmetic means 10. A deviation R is obtained by comparing the position signal with the actual rack position by a position deviation detection means 11. The displacement quantity by which the control rack 2a is to be moved from the preset position is obtained by a second PID arithmetic means 12 so as to control an actuator 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine rotation speed control device that controls an engine so that the engine rotation speed matches a target rotation speed.

[Prior art and its problems] Generally, in this type of control device, PID calculation is performed based on the deviation between the target rotation speed and the actual rotation speed of the engine, and the engine is controlled based on the calculation result. It has become.

Incidentally, the engine speed changes mainly in response to changes in the load on the engine, and when the load changes significantly, the engine speed also changes significantly. Therefore, when performing PID calculation, it is necessary to select a PID that is suitable for both cases where the amount of change in load is large and when the amount of change is small.
A constant should be used.

However, in conventional control devices, a constant PID constant is used regardless of the amount of change in load. In this case, if the P'ID constant is determined to be suitable when the amount of change in load is small, when the amount of change in load is large, it will be difficult to converge until the actual engine speed matches the target speed and becomes stable. The problem arises that it takes time. Conversely, if the PID constant is determined to be suitable when the amount of change in load is large, a problem arises in that overshoot occurs when the amount of change in load is small.

Note that although JP-A-59-202503 describes changing the PID constant depending on the magnitude of the load, no consideration is given to the amount of change in the load. For this reason, the method described in this publication also has the problem of requiring a long time for convergence or of overshooting.

The present invention was made in order to solve the above-mentioned problems, and an object of the present invention is to provide an engine speed control device that can simultaneously solve both the problem of requiring a long time for convergence and the problem of overshooting. shall be.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a PID calculation means that performs PID calculation based on the deviation between the target engine speed and the actual engine speed, and a and a control means for controlling the engine so that the actual engine speed matches the target engine speed based on a calculation result, the load change amount detection detecting the amount of change in the load on the engine. means for determining whether or not the amount of change detected by the load change amount detection means exceeds a predetermined set amount of change; If it is determined that the amount of change in the load exceeds the set amount of change, the PID constant in the stable state is used by the PID calculation means, and if the amount of change in the load is determined to be greater than the set amount of change, the PID constant in the transient state is used as the PID constant in the PID calculation means. The present invention is characterized in that it includes a PID constant setting means used by the calculation means.

[Operation] The load change amount detection means detects the amount of change in load on the engine. The determination means determines whether the amount of change in load detected by the amount of load change detection means exceeds a set amount of change.

When the determination means determines that the amount of change in the load is within the range of the set amount of change, the PID constant setting means sets the stable P
The ID constant is output to the PID calculation means. The PID calculation means performs PMD calculation using the stable PID constant.

On the other hand, if the determination means determines that the amount of change in the load exceeds the set amount of change, the PID constant setting means
The ID constant is output to the PID constant calculation means. The PID calculation means performs PID calculation using the PID constant during transient.

Based on the calculation result of the PrD calculation means, the control means controls the engine so that the actual rotation speed of the engine matches the target rotation speed.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2.
Explain with reference to the diagram. Note that FIG. 1 is a block diagram of a control device according to the present invention.

As shown in FIG. 1, this control device controls the actual rotational speed of the diesel engine 1 by the fuel injection amount of the fuel injection pump 2, and the fuel injection amount of the fuel injection pump 2 is controlled by the fuel injection amount.

It is adjusted by the position of the lever 2a. The position of the control rack 2a is detected by rack position detection means 3. Note that the actual rack position Rr detected by the rack position detecting means 3 is input to a PID constant setting means 9 and a position deviation detecting means 11, which will be described later.

An engine rotation sensor 4 is attached to the engine 1. This engine rotation sensor 4 outputs a pulse signal whose density changes according to the rotation speed of the engine 1, and this pulse signal P is sent to the actual rotation speed calculation means 5 of the control circuit C constituted by a microcomputer. It has been entered. The actual rotation speed calculation means 5 includes a counter for detecting the period of the pulse signal P, measures the period of the pulse signal P by this counter, and calculates the actual rotation speed Nr of the engine l from the result. The actual rotation speed Nr is
It is input to the rotation speed deviation detection means (load change amount detection means) 6.

Further, the rotation speed N1 of the engine 1 set by the target rotation speed setting means 7 is input to the rotation speed deviation detection means 6. Then, the rotation speed deviation detection means 6 detects the deviation ΔN between the target rotation speed Ni and the actual rotation speed Nr (ΔN=N +
−N r). The deviation ΔN is determined by the determination means 8 and the first
It is input to the PID calculation means 1°.

The determining means 8 determines whether the deviation ΔN is within a preset value range.

That is, the determining means 8 determines whether the upper limit value Nu and the lower limit value Nd
(Nd=-Nu), and ΔN>N u
・・・・・・(1) Nd≦ΔN≦Nu ・・・・・・
-(2) ΔN<Nd...Determine which of (3) holds true. The determining means 12 uses the formula (1
) is established, a determination signal Ju is outputted to the PID constant setting means 9, when equation (2) is established, a determination signal Ji is outputted, and when equation (3) is established, a determination signal Jd is outputted to the PID constant setting means 9.

Here, the determination means 8 makes a determination based on the magnitude of the deviation ΔN, in other words, the magnitude of the change in the actual rotation speed Nr. It corresponds to the amount of change in the magnitude of the applied load. Therefore, the determining means 8 indirectly determines whether the amount of change in the load of the engine l exceeds a predetermined range via the amount of change in the actual rotational speed Nr. Further, as is clear from this point, the rotation speed deviation detection means 6 detects the deviation in the load of the engine 1 via the rotation speed.

As shown in FIG. 2, the PID constant setting means 9 includes a constant map 9a for rising, a constant map 9b for stable, a constant map 9C for decreasing, a map selection section 9d, and a constant selection section 9e. .

Constant map for rising time 9a s Constant map for stable time 9b
And the constant map 9C for decreasing time is expressed by the formula (1), respectively.
It is selected when (2) and (3) are satisfied, and in order to eliminate the deviation ΔN as quickly as possible,
P suitable when each formula (1), (2), (3) holds
An ID constant is written.

Normally, when the position of the control lever 2a and the actual rotational speed Nr of the engine 1 are the same, the PID constant of the constant map 9c for decreasing is the largest, and the PTD constant of the constant map 9a for increasing is the largest. The PID constant of the stable constant map 9c is set to be the next largest, and the PID constant of the stable constant map 9c is set to the smallest.

The map selection section 9d receives the judgment signal Ju from the judgment means 8,
Three maps 9a based on Jd and Ji.

Select either 9b or 9c. That is, map 9a is selected when judgment signal Ju is input, map 9c is selected when judgment signal Jd is input, and map 9b is selected when judgment signal Ji is input.

The map selected by the map selection section 9d is input to the constant calculation section 9e. The actual rotational speed Nr of the engine 1 and the actual rack position Rr of the control rack 2a are input to the constant calculation unit 9e. And constant calculation section 9
e calculates a PID constant from the actual rotation speed Nr and the actual rack position Rr based on the map selected by the map selection section 9d. The calculated PID constant is input to the first PID calculation means (PID calculation means) 10.

The first PTD calculation means 10 calculates the deviation ΔN based on the deviation ΔN.
The position of the control rack 2a required to eliminate N is calculated by PID (proportional + integral-sufficient differential calculation). In this calculation, the PID constant set by the PID constant setting means 9 is used. The position signal Ri of the control rack 2a obtained by the calculation is input to the position deviation detection means 11.

The position deviation detection means 11 detects the position of the control rack 2a (hereinafter referred to as
This is called the calculation rack position. ) R1 and rack position detection means 3
The deviation ΔR between the control rack 2a and the actual rack device Rr detected by the control rack 2a is calculated. This deviation △R is the second
It is input to the PID calculation means l2.

The second PID calculation means 12 calculates the PID based on the deviation ΔR.
The amount of displacement by which the control rack 2a should be moved from the current position is calculated. Then, the displacement signal O8 is applied to the actuator 141mtfl via the amplifier 13.

Actuator I4 displaces control rack 2a based on displacement signal O8.

It should be noted that when performing calculations in the second PID calculation means 12, similarly to the calculations in the first PID calculation means 10, it is determined whether the deviation ΔR exceeds a predetermined range, and the PID constant is determined based on the result. You can.

Further, as is clear from the above content, the control means is constituted by the position deviation detection means 11, the second PID calculation means 12, the amplifier 13, the actuator 14, and the fuel injection pump 2.

As mentioned above, when calculating PID in this engine speed control device, when the size of the speed deviation ΔN (amount of change in load on the engine 1) is within a predetermined range, and when it exceeds that range, Since different PID constants are used depending on whether the deviation Δ is large or small, the PrD constant can be set appropriately depending on whether the deviation Δ is large or small. Therefore, the actual rotation speed Nr is the target rotation speed N
The time required for convergence to 1 can be shortened, and open neatness can be prevented.

In particular, in the control device of this embodiment, when the deviation ΔN exceeds the upper limit Nu (when the load on the engine 1 decreases) and when it exceeds the lower limit Nd (when the load on the engine 1 increases) Since the PID constant is changed in each case, the target rotation speed Ni of the actual rotation speed Nr in each case
convergence can be achieved in a much shorter time. That is, when the absolute value of the deviation ΔN is the same, if the same PID constant is used when the load on the engine 1 increases and when it decreases, hunting is likely to occur when the load increases. In this regard, in this embodiment, since the PID constant is changed when the load increases and when the load decreases, such problems can be prevented.

Next, specific test examples are as follows.

In this test, an industrial day cell engine with four cylinders and a displacement of 1500 cc was used as the engine 1, and this was rotated at 1600 rpm. In this state, a load torque of 8 kg-m was applied to the engine, and the load torque was released.

Note that the upper and lower limits of the deviation ΔN are ±25
rpm. In this case, the PID constant exceeds the limit value when the deviation ΔN is turned on and off, but the convergence time is reduced compared to the case where the PID constant used during constant settling is used regardless of load changes. We were able to. Also,
No hunting was observed either when the load was applied or when the load was removed.

Note that this invention is not limited to the above embodiments,
Appropriate changes can be made within the scope of the gist.

For example, in the above embodiment, the amount of change in the load on the engine 1 is detected from the amount of change in the rotation speed of the engine 1, but the load on the engine I may be directly detected, or it may be detected by other means. You may. For example, when using this control device as a control device for a generator engine,
A change in the amount of power generation may be detected. in this case,
The determining means determines whether the amount of change in power generation exceeds a predetermined value, and the PID constant setting means sets a PID constant based on this determination.

Further, although the PID constants are set using the maps 9a, 9b, and 9c, other methods may be adopted.

Furthermore, in the above embodiment, one range regulated by the upper limit value Nu and the lower limit value Nd is defined, or a plurality of ranges are defined by setting a plurality of upper limit values and a plurality of lower limit values, respectively. It is also possible to set different PID constants for each range.

[Effects of the Invention] As explained above, according to the engine speed control device of the present invention, since the PID constant is changed depending on whether or not the amount of change in load exceeds a predetermined range, the actual engine speed is controlled. Effects such as being able to shorten the convergence time until the rotation speed matches the target rotation speed and becoming stable, and preventing overshoot can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, and FIG. 2 is a diagram showing details of the PID constant setting means. This is a diagram. 1...Diesel engine (engine), 2...Fuel injection pump, 2a...Control rack, 3...
U, position detection means, 5. actual rotational speed calculation means, 6.・
Rotation speed deviation detection means (load change amount detection means), 7 Target rotation speed setting means, 8 Judgment means, 9 , , P I
D constant setting means, 10 first PID calculation means (PID
calculation means).

Claims (1)

[Scope of Claims] PID calculation means that performs PID calculation based on the deviation between the target engine speed and the actual engine speed, and the actual engine speed matches the target engine speed based on the calculation result of the PID calculation means. An engine rotation speed control device comprising: a load change amount detection means for detecting a change amount of a load on the engine; and a load change amount detection means for detecting a change amount of a load on the engine; a determining means for determining whether or not the amount of change in the load exceeds a predetermined set change amount;
A PI that causes the PID calculation means to use a transient PID constant when the determination means determines that the amount of change in load exceeds a set amount of change;
An engine rotation speed control device comprising: D constant setting means.