JP5496850B2 - Idle rotation control method and idle rotation control device - Google Patents

Description

  The present invention relates to a rotation control method in an idle rotation state of an internal combustion engine typified by a diesel engine, and more particularly to a method for improving stability and reliability in idle rotation control.

As a conventional device of this type, in the idle engine speed control of the diesel engine, feedback control by so-called PID control (proportional / integral / differential control) is performed, thereby making it possible to ensure the stability of the idle speed. Various devices and the like have been proposed and put into practical use (see, for example, Patent Document 1).
In the PID control of the idle rotation control, the constant of the P (proportional term) term, that is, the P gain is an important factor that greatly affects the stability and startability of the idle rotation control.

For this reason, the P gain is normally measured using a vehicle equipped with a so-called central engine as a reference, under a standard operating environment, for example, at an altitude of 0 m and an outside air temperature of 25 ° C. What is determined based on this is used for actual vehicle control.
However, the actual use environment is often different from the standard use environment as described above. In particular, when the difference is large, the stability of the idle rotation control may be greatly impaired. Therefore, especially in a specific usage environment that affects the stability of idle rotation control, there is a certain degree of control stability in the specific usage environment without disturbing the stability of control in the standard usage environment. In order to ensure, it is usual to perform a so-called adapting operation for adjusting the P gain determined in a standard use environment and finally set the P gain.

JP 09-14031 A (page 3-4, FIGS. 1 to 3)

However, the above-described method has a problem in that it is not always satisfactory because the P gain is determined at the compromise between the problematic use environment and the standard use environment.
For example, if the P gain determined based on an altitude of 0 m is increased to the extent that no engine stall occurs at an altitude of 3000 m, the problem is that the air is thin at an altitude of 3000 m and combustion is weak and easy to stall. On the other hand, at an altitude of 0 m, the behavior of the engine may become so-called hunting.
Also, for example, if the problem is that combustion becomes strong and hunting occurs due to the advance angle of the injection timing at an air temperature of −25 ° C., compared to the standard temperature of 25 ° C. so that hunting does not occur. If the P gain is lowered, an engine stall at 25 ° C. may occur.
Eventually, adjusting and setting the P gain at a compromise according to the malfunction that has occurred will reduce the performance that the engine can originally demonstrate.

  The present invention has been made in view of the above circumstances, and an idle rotation control method capable of realizing appropriate idle rotation control regardless of the use environment of the vehicle without sacrificing the original performance of the engine and An idle rotation control device is provided.

In order to achieve the above object of the present invention, an idle rotation control method according to the present invention includes:
An engine idle speed control method in a vehicle configured such that an engine rotational speed in an idling state is PID-controlled based on a difference between an actual rotational speed of the engine and a target rotational speed,
In the idling state, the PID control is temporarily stopped, the fuel injection amount is changed for a short time, an actual value of P gain is obtained based on the operating state of the engine at that time, and then the actual measurement of the P gain is performed. The ratio of the P gain standard value in the PID control to the value is calculated, the calculation result is stored as a P gain correction coefficient learning value in the learning value map together with the temperature and altitude at the time of the calculation, and during the PID control, The P gain standard value can be corrected by the P gain correction coefficient stored in the learning value map corresponding to the temperature and altitude at that time.
In order to achieve the above object of the present invention, an idle rotation control device according to the present invention includes:
Idle of a vehicle comprising an electronic control unit configured to perform PID control on the rotational speed of an engine in an idling state based on the difference between the actual rotational speed of the engine and the calculated target rotational speed A rotational speed control device,
In the idling state, the electronic control unit temporarily stops the PID control, changes the fuel injection amount for a short time, obtains an actual value of P gain based on the operating state of the engine at that time, The ratio of the P gain standard value in the PID control to the measured value of the P gain is calculated, the calculation result is stored as a P gain correction coefficient learning value in the learning value map together with the temperature and altitude at the time of the calculation, In PID control, the P gain standard value can be corrected by a P gain correction coefficient stored in the learning value map corresponding to the temperature and altitude at that time.

  According to the present invention, the P gain in the PID control of the idle rotation control can be corrected by the correction coefficient acquired for various combinations of temperature and altitude, and the PID control corresponding to the actual operation state of the engine can be executed. Thus, unlike the prior art, there is an effect that appropriate idle rotation control can be realized regardless of the use environment of the vehicle without sacrificing the original performance of the engine.

It is a block diagram which shows the structural example of the common rail type fuel-injection control apparatus to which idle rotation control in embodiment of this invention is applied. It is a subroutine flowchart which shows the procedure of the idle rotation control process performed by the electronic control unit which comprises the common rail type fuel injection control apparatus shown by FIG. It is a schematic diagram for demonstrating the gain measurement map used in the idle rotation control process in embodiment of this invention. It is a schematic diagram for demonstrating the P gain correction coefficient learning value map used in the idle rotation control process in embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4.
The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
First, the configuration of a common rail fuel injection control device to which idle rotation control according to an embodiment of the present invention is applied will be described with reference to FIG.
The common rail fuel injection control device includes a high pressure pump device 50 that pumps high pressure fuel, a common rail 1 that stores the high pressure fuel pumped by the high pressure pump device 50, and a high pressure fuel supplied from the common rail 1 as a diesel engine. A plurality of injectors 2-1 to 2-n (hereinafter referred to as “engines”) that inject and supply to three cylinders, and an electronic control unit (in FIG. 4 is a main constituent element.
Such a configuration itself is the same as the basic configuration of this type of fuel injection control apparatus that has been well known.

The high-pressure pump device 50 has a known and well-known configuration with the supply pump 5, the metering valve 6, and the high-pressure pump 7 as main components.
In this configuration, the fuel in the fuel tank 9 is pumped up by the supply pump 5 and supplied to the high-pressure pump 7 through the metering valve 6. As the metering valve 6, an electromagnetic proportional control valve is used, and the amount of energization is controlled by the electronic control unit 4, so that the flow rate of fuel supplied to the high-pressure pump 7, in other words, the discharge of the high-pressure pump 7. The amount is to be adjusted.

A return valve 8 is provided between the output side of the supply pump 5 and the fuel tank 9 so that surplus fuel on the output side of the supply pump 5 can be returned to the fuel tank 9. .
The supply pump 5 may be provided separately from the high-pressure pump device 50 on the upstream side of the high-pressure pump device 50 or may be provided in the fuel tank 9.
The injectors 2-1 to 2-n are provided for each cylinder of the engine 3, are supplied with high-pressure fuel from the common rail 1, and perform fuel injection by injection control by the electronic control unit 4. As the injectors 2-1 to 2-n in the embodiment of the present invention, for example, a so-called solenoid valve type that has been conventionally used is suitable.

The electronic control unit 4 includes, for example, a microcomputer 21 (see FIG. 2) having a known and well-known configuration, a storage element (not shown) such as a RAM and a ROM, and an injector 2-1. A circuit (not shown) for energizing and driving .about.2-n and a circuit (not shown) for energizing and driving the metering valve 6 and the like are configured as main components.
In addition to the detection signal of the pressure sensor 11 that detects the pressure of the common rail 1 being input to the electronic control unit 4, various detection signals such as the engine speed, the accelerator opening, the outside air temperature, and the atmospheric pressure are received by the engine 3. It is input to be used for the operation control and fuel injection control.

In particular, the electronic control unit 4 according to the embodiment of the present invention is configured to perform idle rotation control by PID control, as in the prior art.
That is, in the idling speed control by the PID control, the target idling speed of the engine 3 is calculated and calculated based on the operation information of the engine 3, that is, information such as the engine speed and the amount of depression of the accelerator. Feedback control based on PID control is performed so that the actual engine speed detected by the rotation sensor that is not used becomes the target idle speed.

  Further, in the electronic control unit 4 according to the embodiment of the present invention, a P gain measurement value map (indicated as “MAP1” in FIG. 1) 11 in an appropriate storage area will be described in detail later, A P gain correction coefficient learning value map (indicated as “MAP2” in FIG. 1) 12 is stored, and is used for idle rotation control processing in the embodiment of the present invention, as will be described later. Yes.

FIG. 2 is a subroutine flowchart showing the procedure of the idle rotation control process executed by the electronic control unit 4 in the embodiment of the present invention. Hereinafter, the embodiment of the present invention will be described with reference to FIG. The idle rotation control process in will be described.
The idle rotation control process shown in FIG. 2 is one of the subroutine processes while the electronic control unit 4 performs various engine control processes, fuel injection control processes, and the like as described above. It is to be executed as one.
First, the outline of the idle rotation control process according to the embodiment of the present invention will be described. The idle rotation control process according to the present invention is performed by feedback control based on PID control as in the conventional case as described above. In particular, the P gain correction coefficient for correcting the constant of the P term (proportional term) in the PID control according to the actual operating characteristics of the engine 3 is learned, and the learning is performed. The value can be used for correction of P gain in PID control.

Hereinafter, specifically, when the process is started by the electronic control unit 4, it is first determined whether or not the P gain learning process can be executed (in FIG. 2). (See step S102).
The P gain learning process in the embodiment of the present invention can be executed when the engine 3 is in an idling state, and the specific conditions are as follows. That is, the engine speed is equal to or less than a predetermined number, the fuel injection amount is equal to or less than the predetermined injection amount, the accelerator opening is 0% (the accelerator (not shown) is not stepped on), and the clutch (not shown) There are five conditions that the engine 3 is not stepped on and that the engine 3 is in a so-called warm-up operation state.

Here, since it is assumed that the electronic control unit 4 in the embodiment of the present invention is configured to execute fuel injection control as in the prior art, a new fuel injection amount is acquired in this step 102. However, it is preferable to use the fuel injection amount calculated and calculated in the fuel injection control process executed separately.
Further, information on whether or not the clutch (not shown) is stepped on is omitted in FIG. 1, but as in the conventional case, from the clutch device not shown in the electronic control unit 4, like the information on the accelerator opening. Whether or not a clutch (not shown) is stepped on can be determined based on whether or not the input signal is at a predetermined level.
It should be noted that it is preferable that the reference value such as the predetermined rotation speed in each of the above-described condition determinations is set to an appropriate value individually based on a test or a simulation result according to the scale of the engine 3 or the like.

  As described above, when it is determined in step S102 that the P gain learning process is possible (in the case of YES), the process proceeds to the process of step S104 described below, while the P gain learning process is not possible. Is determined (NO), the series of processing ends, and the process returns to the main routine (not shown).

In step S104, step injection is executed.
That is, in step S104, first, the idle rotation control is temporarily stopped by the electronic control unit 4, and then fuel injection of a predetermined injection amount is performed for an extremely short time, that is, step injection is performed. . In other words, in the embodiment of the present invention, in the step injection, when the injection amount immediately before the execution of the step injection is Q1 (mm3 / st), for example, the injection amount is Q2 (Q2> Q1) ( (mm3 / st) to increase the injection, that is, to change the fuel injection amount.
More specifically, the temporary stop of the idle rotation control is preferably performed by stopping the calculation of the I term (integral term) of the PID control in the idle rotation control.
Further, the step injection execution time is about 1 to 2 seconds, and the fuel injection amount is a slight amount that does not give the vehicle occupant an uncomfortable feeling due to the step fuel injection. Etc., and should be determined on the basis of the results of tests and simulations.

Next, the rotational speed change amount measurement is performed as one element representing the operation state of the engine 3 with respect to the previous step injection (S104 in FIG. 2) (see step S106 in FIG. 2).
The amount of change in the rotational speed in step S106 is defined as the amount of change in the engine rotational speed per unit time at the time of the above-described step injection, and is specifically obtained as described below.
The electronic control unit 4 acquires the respective engine speeds immediately before the execution of the process of step S104 and immediately after the execution of the step injection, and immediately before the execution of the process of step S104. Assuming that the engine speed is Nt1 for the sake of convenience and the engine speed immediately after the step injection is executed for the convenience of Nt2, the speed change amount = (Nt2−Nt1) is calculated.

Next, a P gain measurement value is calculated (see step S108 in FIG. 2).
That is, the P gain measurement value (actual measurement value of P gain) based on the operating state of the engine 3 for the previous step injection (see step S104 in FIG. 2) is P gain measurement value = rotational speed change amount / injection amount change amount. It is required. Here, the P gain is a name of a constant used for the calculation process of the P term (proportional term) in the PID control. Further, the rotation speed change amount is obtained in the process of step S106. Furthermore, if the injection amount in the idling rotation control state immediately before execution of step injection is Q1 (mm3 / st) and the injection amount at the time of step injection execution is Q2 (mm3 / st), the injection amount change amount is (Q2-Q1). It is expressed. Therefore, the P gain measurement value is expressed as P gain measurement value = rotational speed change amount / injection amount change amount = Nt2−Nt1) ÷ (Q2−Q1).

Next, the P gain measurement value calculated as described above is stored in the P gain measurement value map 11 (see step S110 in FIG. 2).
Here, as shown in FIG. 3, the P gain measurement value map 11 stores the P gain measurement value calculated in the process of step S108 at the lattice point using the outside air temperature and the altitude as parameters. It is set in an appropriate storage area of the electronic control unit 4.
In FIG. 3, three specific numerical values of the P gain measurement value are exemplified. If one of them is described as a representative example, at an altitude of 0 m and an outside air temperature of −25 ° C., the rotational speed change amount = 160 ( rpm) and the injection amount change amount = 32 (mm 3 / st), an example in which the P gain measurement value is 32 is shown.

Therefore, in step S110, first, the outside air temperature and altitude at the time of processing in step S110 are acquired. Here, as described above, the outside air temperature is input to the electronic control unit 4 from an external sensor (not shown). On the other hand, the altitude is obtained by a known arithmetic expression for calculating the altitude from the atmospheric pressure, and the atmospheric pressure is input to the electronic control unit 4 by an atmospheric pressure sensor (not shown) (FIG. 1).
After the outside air temperature and altitude are acquired as described above, the P gain measurement value obtained in step S108 is stored at the lattice point of the outside air temperature and altitude in the P gain measurement value map 11 described above. It will be.

Next, calculation calculation of a P gain correction coefficient learning value is performed (see step S112 in FIG. 2).
First, the P gain correction coefficient learning value is obtained as P gain correction coefficient learning value = applied measurement value ÷ P gain measurement value. Here, the measurement value at the time of adaptation corresponds to the previous P gain measurement value acquired in advance in a standard environmental state, for example, at an altitude of 0 m and an air temperature of 25 ° C., in a vehicle equipped with a so-called central engine serving as a reference. It is a measured value. The measurement value at the time of adaptation is stored in an appropriate storage area of the electronic control unit 4, and is originally used for PID control in idle rotation control. In step S112, it may be used. Is.

Next, it is determined whether or not the P gain correction coefficient learning value calculated as described above is within a predetermined limit (see step “S114” in FIG. 2), and is determined to be within the predetermined limit. In this case (in the case of YES), the process proceeds to step S116 described below. On the other hand, in the case where it is determined that it is not within the predetermined limit (in the case of NO), the current learning of the P gain correction coefficient is not effective. As a result, the series of processing is terminated and the process returns to the main routine (not shown) .The predetermined limit is determined from the viewpoint of not impairing the stability of the PID control. Appropriate values should be determined based on the results of tests and simulations, taking into account the conditions of individual vehicles.
In step 116, the P gain correction coefficient learning value calculated in step S112 is written and stored in the P gain correction coefficient learning value map 12, and the learning value is updated. In addition, after the process of step S116, it will once return to the main routine which is not shown in figure.

As schematically shown in FIG. 4, the P gain correction coefficient learning value map 12 has the outside air temperature and altitude as input parameters, and the calculated P gain correction coefficient is calculated at the lattice points of these two parameters. The learning value is stored, and the P gain correction coefficient learning value map 12 is stored in an appropriate storage area of the electronic control unit 4 as described above.
In FIG. 4, three specific numerical values of the P gain correction coefficient learning value are exemplified. If one of them is described as a representative, the measured value at the time of adaptation at an altitude of 0 m and an outside air temperature of −25 ° C. = 20 shows an example in which, when P gain measurement value = 32, the P gain correction coefficient learning value is 0.625.
Thus, the outside air temperature and altitude required for storing the P gain correction coefficient learning value in step S116 in the P gain correction coefficient learning value map 12 are the outside air temperature and the altitude referenced in the learning value calculation in step S112. Same as elevation.

In the PID control executed in the idle rotation control process, the P gain correction coefficient learning value corresponding to the outside air temperature and the altitude during the control execution is read from the P gain correction coefficient learning value map 12, Multiplication is performed as a multiplier of a predetermined P gain (P term constant), and the multiplication result is used for PID control as a corrected P gain.
Therefore, in the embodiment of the present invention, the P gain of the PID control in the idling rotation control of the engine 3 is set to an appropriate value according to the actual operating state of the engine 3, and therefore different from the conventional one. The rear performance of the engine 3 is sufficiently exhibited.

In the above-described embodiment of the present invention, step injection is performed (see step S104 in FIG. 2), and the P gain measurement value is obtained as P gain measurement value = rotational speed change amount / injection amount change amount. However, a torque change amount may be used instead of the injection amount change amount.
In general, in fuel injection control, the torque required for the engine 3 is calculated based on accelerator opening information and the like, and the calculated torque is converted into the required fuel injection amount. Is stipulated.
Therefore, the torque calculated and calculated by the fuel injection control process before and after the step injection is used to obtain the difference, and this is used as the torque change amount as the divisor of the rotational speed change amount. Is preferred.

  In the embodiment of the present invention described above, the case of the diesel engine 3 to which the common rail fuel injection control device is applied has been described as an example. However, the idle rotation control process and the idle rotation in the embodiment of the present invention are described. The control device is not limited to an engine having such a configuration, and can be similarly applied as long as the engine is configured such that fuel injection control is executed by an electronic device.

  It is suitable for an electronically controlled fuel injection device that performs idle rotation control by PID control.

DESCRIPTION OF SYMBOLS 1 ... Common rail 2-1-2-n ... Injector 3 ... Engine 4 ... Electronic control unit 11 ... P gain measurement value map 12 ... P gain correction coefficient learning value map

Claims (8)

An engine idle speed control method in a vehicle configured such that an engine rotational speed in an idling state is PID-controlled based on a difference between an actual rotational speed of the engine and a target rotational speed,
In the idling state, the PID control is temporarily stopped, the fuel injection amount is changed for a short time, an actual value of P gain is obtained based on the operating state of the engine at that time, and then the actual measurement of the P gain is performed. The ratio of the P gain standard value in the PID control to the value is calculated, the calculation result is stored as a P gain correction coefficient learning value in the learning value map together with the temperature and altitude at the time of the calculation, and during the PID control, An idle rotation control method, wherein the P gain standard value can be corrected by a P gain correction coefficient stored in the learning value map corresponding to the temperature and altitude at that time.   The measured value of P gain is calculated as the ratio of the engine speed change amount when the fuel injection amount is changed for the short time to the fuel injection amount change amount when the fuel injection amount is changed for the short time. The idle rotation control method according to claim 1, wherein:   The measured value of P gain is calculated as the ratio of the engine speed change amount when the fuel injection amount is changed for the short time to the torque change amount when the fuel injection amount is changed for a short time. The idle rotation control method according to claim 1, wherein:   4. The idle rotation control method according to claim 1, wherein the P gain correction coefficient learned value is stored in a learned value map when the learned value is within a predetermined range. 5. Idle of a vehicle comprising an electronic control unit configured to perform PID control on the rotational speed of an engine in an idling state based on the difference between the actual rotational speed of the engine and the calculated target rotational speed A rotational speed control device,
In the idling state, the electronic control unit temporarily stops the PID control, changes the fuel injection amount for a short time, obtains an actual value of P gain based on the operating state of the engine at that time, The ratio of the P gain standard value in the PID control to the measured value of the P gain is calculated, the calculation result is stored as a P gain correction coefficient learning value in the learning value map together with the temperature and altitude at the time of the calculation, Idle rotation control characterized in that the P gain standard value can be corrected by the P gain correction coefficient stored in the learning value map corresponding to the temperature and altitude at that time in the PID control. apparatus.   The electronic control unit measures the actual value of P gain as the ratio of the engine speed change amount when the fuel injection amount is changed for the short time to the fuel injection amount change amount when the fuel injection amount is changed for a short time. The idle rotation control device according to claim 5, wherein the idle rotation control device is configured to calculate.   The electronic control unit calculates the actual value of P gain as the ratio of the engine speed change amount when the fuel injection amount is changed for the short time to the torque change amount when the fuel injection amount is changed for a short time. The idle rotation control device according to claim 5, wherein the idle rotation control device is configured to do so.   The electronic control unit is configured to store the P gain correction coefficient learning value in a learning value map when it is determined that the learning value is within a predetermined range. The idle rotation speed control device according to claim 7.

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