JP2009209852A - Idling control device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure stability in idling control even if a standard ignition time in idling is set at the optimum ignition time. <P>SOLUTION: This idling control device for engine comprises a means 121 for computing a basic command value of input to a controlled object in response to operating condition of a vehicle, a means 123 including a reverse system of response characteristics of an intake system and a model response of the intake system and for computing a phase compensation value based on the basic command value, a means for controlling the intake air quantity of the engine based on the phase compensation value, a means 122 for computing a model command value based on the basic command value and a model response of the intake system, a means 125 for taking a deviation between the basic command value and the model command value as a torque correction value, a means for controlling ignition time of the engine in response to the torque correction value, and a means 124 for switching the model response of the intake system to a quick response characteristic when the torque correction value is a positive value and for switching the modes response of the intake system to a low response characteristic when the torque correction value is a negative value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an engine idle control device.

As a conventional engine idle control device, when the engine speed fluctuates due to changes in engine load caused by auxiliary equipment, disturbances, etc., the intake air amount and ignition timing are controlled to set the engine speed to the target idle speed. There is one that converges on the speed (see, for example, Patent Document 1).
JP 2006-138300 A

  However, the above-described conventional engine idle control device, in the torque designation value for matching the engine rotation speed to the target idle rotation speed, detects a shortage of the torque command value due to the response delay of the intake system, and performs a quick response. Compensating with time, the engine speed was converged to the target idle speed.

  If the reference ignition timing at the time of idling is set to an optimum ignition timing (MBT: Minimum Advance for Best Torque) at which the maximum torque can be obtained, the torque cannot be increased even if the ignition timing is advanced or retarded. For this reason, if the reference ignition timing during idling is set to the optimum ignition timing, torque decrease correction can be performed by ignition timing, but torque increase correction cannot be performed. Therefore, there is a problem that the stability of idle control deteriorates.

  The present invention has been made paying attention to such conventional problems, and aims to ensure the stability of idle control even when the reference ignition timing at the time of idling is set to the optimum ignition timing. .

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention is an idle control device for an engine (1), which is a target value calculation means (121, S31) for calculating a basic command value of an input to a controlled object according to a driving state of a vehicle, and a response of an intake system Dynamic characteristic compensation means (123, S35) for calculating a phase compensation value based on the basic command value, including an inverse system of the characteristic Gp (s) and a reference response Gm (s) of the intake system; and the phase In accordance with the compensation value, the reference command value is calculated based on the intake air amount control means (140) for controlling the intake air amount of the engine, and the basic command value and the reference response Gm (s) of the intake system. A reference command value calculation means (122), a torque correction value calculation means (125, S35) that uses a deviation between the basic command value and the reference command value as a torque correction value, and the engine correction value according to the torque correction value. Ignition timing for controlling ignition timing When the torque correction value is a positive value, the reference response Gm (s) of the intake system is switched to a fast response characteristic, and when the torque correction value is a negative value, the reference response of the intake system Response characteristic switching means (124, S33, S34) for switching Gm (s) to a slow response characteristic.

  In the region where torque correction by ignition timing control is possible, the reference response characteristic of the intake system is delayed so that the response characteristic of the intake system does not saturate, and the shortage of torque due to the response delay of the intake system is controlled by the ignition timing control with a quick response. Can be compensated. On the other hand, in a region where torque correction by ignition timing control is impossible, the dependence on ignition timing control can be reduced by increasing the reference response characteristics of the intake system.

  Therefore, even when the reference ignition timing during idling is set to the optimum ignition timing, engine speed fluctuations can be suppressed, and stable idling control can be performed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic configuration diagram of an engine idle control device according to a first embodiment of the present invention.

  The engine 1 includes a cylinder block 2 and a cylinder head 3 that covers the top of the cylinder block 2.

  The cylinder block 2 is formed with a plurality of cylinders 2a. In FIG. 1, one cylinder 2a is shown in order to prevent the drawing from being complicated and to facilitate understanding of the invention. A piston 4 is slidably fitted into the cylinder 2a. The cylinder block 2, the cylinder head 3, and the piston 4 define a pent roof type combustion chamber 5. A spark plug 6 is disposed at the center of the top wall of the combustion chamber 5.

  The cylinder head 3 is formed with an intake passage 20 and an exhaust passage 30 that open to the top wall of the combustion chamber 5. The intake valve 21 opens and closes the opening of the intake passage 20, and the exhaust valve 31 opens and closes the opening of the exhaust passage 30.

  The intake passage 20 is provided with an air cleaner 22, an air flow sensor 23, a throttle valve 24, and a fuel injection valve 25 in order from the upstream.

  The air cleaner 22 removes foreign substances contained in the air.

  The air flow sensor 23 detects the flow rate (intake amount) of air taken into the engine 1.

  The throttle valve 24 adjusts the flow rate of air flowing into the intake manifold 26. The opening degree of the throttle valve 24 is detected by a throttle sensor 27.

  The fuel injection valve 25 injects fuel according to the engine operating state.

  The controller 40 includes a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). In addition to the sensor signals described above, the controller 40 detects an engine rotation speed sensor 41 that detects the engine rotation speed based on the crank angle, an engine water temperature sensor 42 that detects the water temperature of the engine 1, and an accelerator pedal depression amount. Signals from various sensors such as the accelerator stroke sensor 43 are input. Based on detection signals from these various sensors, the controller 40 optimally controls the fuel injection amount, ignition timing, and the like according to the operating state. Hereinafter, idle control according to this embodiment executed by the controller 40 will be described.

  FIG. 2 is a block diagram illustrating the idle control unit 100 of the controller 40.

  The idle control unit 100 includes a feedforward compensation unit (hereinafter referred to as “F / F compensation unit”) 110, a feedback compensation unit (hereinafter referred to as “F / B compensation unit”) 120, an ignition timing control unit 130, and intake air. A quantity control unit 140, an adder 150, and an adder 160 are provided.

The engine water temperature, the engine load, and the target engine rotation speed are input to the F / F compensation unit 110. Based on these input values, F / F compensation unit 110, a feed-forward torque command value (hereinafter "intake system F / F torque command value" hereinafter) T _Q _ _FF of the intake system, feed-forward torque command of the ignition system A value (hereinafter referred to as “ignition system F / F torque command value”) T _{ADV — FF} is calculated. The F / F compensation unit 110 calculates an intake system F / F torque command value T _{Q — FF} and an ignition system F / F torque command value T _{ADV — FF} by referring to a map stored in advance in the memory. To do.

The target engine speed and the actual engine speed are input to the F / B compensation unit 120. Based on these input values, the F / B compensator 120 uses an intake system feedback torque command value (hereinafter referred to as an “intake system F / B torque command value”) to match the actual engine rotational speed to the target rotational speed. ) T _{Q — FB} and an ignition system feedback torque command value (hereinafter referred to as “ignition system F / B torque command value”) T _{ADV — FB} are calculated. Details of the F / B compensator 120 will be described later with reference to FIG.

The adder 150 calculates an ignition system torque command value T _ADV by the following equation (1).

The adder 160 calculates the intake system torque command value T _Q by the following equation (2).

An ignition system torque command value T _ADV is input to the ignition timing control unit 130. The ignition timing control unit 130 calculates a target ignition timing according to the ignition system torque command value T _ADV and controls the ignition timing of the spark plug 6 so as to be the target ignition timing.

An intake system torque command value _TQ is input to the intake air amount control unit 140. Intake air amount control unit 140 calculates a target throttle opening degree in accordance with the intake system torque command value T _Q, so as to match the target throttle opening, controlling the throttle valve 24.

  FIG. 3 is a block diagram showing details of the F / B compensation unit 120.

  The F / B compensation unit 120 includes an F / B control unit 121, an intake system torque reference value calculation unit 122, a phase compensation unit 123, a positive / negative sign determination unit 124, and a subtractor 125.

The F / B control unit 121 performs F / B compensation of the following expression (3) on the deviation between the target engine speed and the actual engine speed, and calculates the F / B torque command value T _FB . Equation (3) is actually calculated using a recurrence equation obtained by discretization by Tustin approximation or the like. The control constants K _p , K _i , K _d in the equation (3) and the time constant T _DIV of the first order approximate differential filter are determined in consideration of the gain margin and the phase margin.

The intake system torque reference value calculation unit 122 receives the F / B torque command value T _FB and uses a transfer function (reference response characteristic) G _m (s) of the intake system reference model shown in the following equation (4). To calculate the intake system torque reference value. The method for determining the time constant T _{ref in} equation (4) will be described in detail later, but is determined based on the determination result of the positive / negative sign determination unit.

The subtractor 125 calculates an ignition system F / B torque command value T _{ADV — FB} , which is a deviation between the F / B torque command value T _FB and the intake system torque reference value (see equation (5)).

The phase compensator 123 has the F / B torque command value T _FB as an input, and the transfer function G _m (s) of the intake system reference model and the transfer function Gp ( Phase compensation is performed by a filter composed of the product of the inverse system of s) and an intake system torque command value T _{Q — FB} is calculated (see equation (7)). The time constant T _qa in the equation (6) will be described later with reference to FIG.

The positive / negative sign determination unit 124 determines whether the sign of the previous value T _{ADV — FBZ} of the ignition system F / B torque command value output from the delay operator 126 is positive or negative.

Here, when the previous value T _{ADV — FBZ} of the ignition system F / B torque command value is positive (T _{ADV — FBZ} ≧ 0), the intake system torque reference value calculator 122 and the phase compensator 123 determine the intake system In order to make the reference response characteristic a fast response characteristic, the time constant T _ref of the transfer function G _m (s) is set to T _ref = T _fast .

On the other hand, when the previous value T _{ADV — FBZ} of the ignition system F / B torque command value is negative (T _{ADV — FBZ} <0), the intake system norm response is calculated in the intake system torque norm calculation unit and the phase compensator. To make the characteristic a slow response characteristic, the time constant T _ref of the transfer function G _m (s) is set to T _ref = T _slow (> T _fast ).

Hereinafter, the reason why the time constant T _ref of the transfer function G _m (s) is switched based on the sign of the previous value T _{ADV — FBZ} of the ignition system F / B torque command value will be described.

  As described above, when the reference ignition timing during idling is set to the optimum ignition timing (MBT) at which the maximum torque can be obtained, the torque cannot be increased even if the ignition timing is advanced or retarded. That is, by controlling the ignition timing, the torque can be reduced, but the torque cannot be increased. Since the advance angle correction from the optimal ignition timing may cause knocking, in practice, only torque reduction correction based on the retard of the ignition timing can be performed.

  Further, since it takes time from the time when the throttle valve 24 is controlled until the air corresponding to the change is sucked to generate torque, the torque does not rise in steps even if the throttle valve 24 is moved in steps. That is, the rising speed of the response characteristic of the intake system has a saturation characteristic. Therefore, if the response characteristic of the intake system matched with the reference response characteristic of the intake system is saturated, the control tends to become unstable.

  For this reason, in a region where torque correction by ignition timing control is possible, it is desirable to delay the intake system normative response characteristic to such an extent that the intake system response characteristic is not saturated, and to compensate by ignition timing control as much as possible.

  On the other hand, in the region where torque correction by ignition timing control is not possible, the response characteristic of the intake system may be saturated, so the reference response characteristic of the intake system can be made faster and the dependence by ignition timing control can be made as small as possible. It is desirable to do.

Therefore, in this embodiment, when the previous value T _ADV _ _FBZ the ignition system F / B torque command value is positive, i.e., when the torque increase correction by the ignition timing control is required, the nominal response characteristics of the intake system As a quick response characteristic, the dependence on the ignition timing control is reduced.

On the other hand, when the previous value T _ADV _ _FBZ of the ignition system F / B torque command value is negative, i.e., when the torque reduction correction by the ignition timing control is required, as slow response characteristic nominal response characteristic of the intake system Dependency on quick ignition timing control is increased.

FIG. 4 is a table for setting the time constant T _qa of the transfer function Gp (s) indicating the response characteristic of the intake system.

  After the throttle valve 24 is controlled, it takes time until the air corresponding to the change is sucked into the cylinder to generate torque. This time varies depending on the operating state of the engine 1.

Therefore, in this embodiment, as shown in FIG. 4, the time constant T _qa is set to be smaller as the engine speed is higher. That is, the response characteristic of the intake system is set to be faster as the engine speed is higher.

  As a result, the inconsistency between the response characteristic Gp (s) of the intake system and the actual response characteristic can be prevented, and the stability of the idle control can be improved.

  FIG. 5 is a flowchart illustrating the idle control according to the present embodiment. The controller 40 repeatedly executes this routine at a predetermined calculation cycle during engine operation.

  In step S1, the controller 40 determines whether or not the engine operating state is an idle operating state. Specifically, it is determined based on an input signal from the accelerator stroke sensor 43 whether or not the accelerator pedal is depressed. If the accelerator pedal is not depressed, the controller 40 determines that the engine is in the idle operation state, and proceeds to step S2. On the other hand, if the accelerator pedal is depressed, the current process is terminated.

In step S2, the controller 40 calculates an intake system F / F torque command value T _{Q — FF} and an ignition system F / F torque command value T _{ADV — FF} . Specifically, it is calculated by referring to a map stored in advance in the memory in accordance with the engine water temperature, the engine load, and the target engine speed.

In step S3, the controller 40 calculates the intake system F / B torque command value T _{Q — FB} and the ignition system F / B torque command value T _{ADV — FB} . Specific contents will be described later with reference to FIG.

In step S4, the controller 40 calculates the intake system torque command value _TQ and the ignition system torque command value _TADV .

  FIG. 6 is a flowchart for explaining the calculation process of the F / B compensation unit 120.

In step S31, the controller 40 calculates an F / B torque command value T _FB for making the engine speed coincide with the target engine speed.

In step S32, the controller 40 determines whether or not the sign of the previous value T _{ADV — FBZ} of the ignition system F / B torque command value is positive. If the sign of the previous value T _{ADV — FBZ} of the ignition system F / B torque command value is positive (T _{ADV — FBZ} ≧ 0), the controller 40 _proceeds to step S33. On the other hand, if the sign of the previous value T _{ADV — FBZ} of the ignition system F / B torque command value is negative (T _{ADV — FBZ} <0), the process proceeds to step S34.

In step S33, the controller 40 sets the time constant T _ref to T _ref = T _fast in order to make the reference response characteristic of the intake system a fast response characteristic.

In step S34, the controller 40 sets the time constant T _ref to T _ref = T _slow (> T _fast ) in order to make the reference response characteristic of the intake system a slow response characteristic.

In step S35, the controller 40 calculates the intake system F / B torque command value T _{Q — FB} and the ignition system F / B torque command value T _{ADV — FB} .

  FIG. 7 is a time chart for explaining the idle control according to the present embodiment. In order to facilitate understanding of the invention, a conventional example is indicated by a broken line. Hereinafter, in order to clarify the correspondence with the flowchart of FIG.

  When the load torque is input to the engine at time t1 (FIG. 7A) and the engine rotation speed decreases (FIG. 7B), the controller 40 matches the engine rotation speed with the target idle rotation speed. The idle control according to the present embodiment is executed.

From time t1 to time t2, the ignition system F / B torque command value T _{ADV — FB} output from the subtractor 125 is a positive value (FIG. 7F; Yes in S32). Therefore, the controller 40 sets the time constant T _ref of the transfer function G _m (s) to T _ref in order to make the intake system reference response characteristic a fast response characteristic in the intake system torque reference value calculation unit 122 and the phase compensator 123. = T _fast (FIG. 7G; S33).

Note that the positive value of the ignition system F / B torque command value T _{ADV — FB} means that torque increase correction by ignition timing control is required, but the maximum torque can be obtained at the reference ignition timing during idling. The optimal ignition timing is set. Therefore, the controller 40 does not correct the ignition timing (FIG. 7E).

  Thus, when ignition timing control cannot be performed, the reference response characteristic of the intake system is set to a quick response characteristic, so that a decrease in engine rotation speed can be suppressed as compared to the conventional example (FIG. 7B). .

From time t2 to t3, the ignition system F / B torque command value T _{ADV — FB} output from the adder is a negative value (FIG. 7F; No in S32). Accordingly, the controller 40 sets the time constant T _ref of the transfer function G _m (s) to T _ref in order to make the intake system reference response characteristic slow response characteristics in the intake system torque reference value calculation unit 122 and the phase compensator 123. = T _slow (FIG. 7 (G); S34).

Further, the negative value of the ignition system F / B torque command value T _{ADV — FB} means that torque reduction correction by ignition timing control is required. Therefore, the controller 40 corrects the ignition timing by retarding (FIG. 7E).

  Thus, when ignition timing control can be performed, the shortage of torque due to response delay of the intake system can be compensated by ignition timing control having a quick response. As a result, a decrease in the engine rotation speed can be suppressed as a whole, and vibration can be reduced (FIG. 7B).

  From time t3 to t4, the same thing as time t1 to t2 described above is carried out, so the description is omitted. Similarly, from time t4 to t5, the same operation as from time t2 to t3 described above is performed, and thus the description thereof is omitted.

  According to the present embodiment described above, the response of the intake system matches the transfer function (reference response characteristic) Gm (s) of the reference model of the intake system by performing phase advance compensation on the torque command value to the intake system. Let Then, the torque shortage due to the response delay of the intake system is distributed as a torque command value to the ignition system. Then, based on the sign of the torque command value to the ignition system, the reference response characteristic Gm (s) of the intake system is switched.

  Specifically, when the torque command value to the ignition system is positive, the reference response characteristic Gm (s) is switched to a fast response characteristic to reduce the dependence on the ignition timing control. On the other hand, when the torque command value to the ignition system is negative, the reference response characteristic Gm (s) is switched to the slow response characteristic, and the dependence of the ignition timing control having a quick response is increased.

  In this way, in the region where torque correction by ignition timing control is possible, the reference response characteristic of the intake system is delayed to such an extent that the response characteristic of the intake system is not saturated, and the shortage of torque due to the response delay of the intake system is ignited quickly. Compensation can be made by timing control. On the other hand, in a region where torque correction by ignition timing control is impossible, the dependence on ignition timing control can be reduced by increasing the reference response characteristics of the intake system.

  As a result, even when the reference ignition timing during idling is set to the optimal ignition timing, fluctuations in the rotational speed of the engine 1 can be suppressed, and stable idling control can be performed.

Further, the time constant T _qa of the transfer function Gp (s) indicating the response characteristic of the intake system is set so as to decrease as the engine speed increases. As a result, mismatch between the response characteristic Gp (s) of the intake system and the actual response characteristic can be prevented, so that the stability of idle control can be further improved.

(Second Embodiment)
Next, idle control according to the second embodiment of the present invention will be described. The second embodiment of the present invention is different from the first embodiment in that a torque change rate restriction is applied to the intake system torque reference value output from the intake system torque reference value calculation unit 122 in consideration of the saturation characteristics of the intake system. Is different. Hereinafter, the difference will be described. In addition, the description which overlaps using the same code | symbol to the part which fulfill | performs the same function as 1st Embodiment mentioned above is abbreviate | omitted suitably.

  FIG. 8 is a block diagram illustrating details of the F / B compensation unit 120 according to the present embodiment.

  The intake system torque reference value output from the intake system torque reference value calculator 122 is input to the torque change rate limiting unit 201. The torque change rate limiting unit 201 limits the torque change rate so as not to exceed a certain value even when the response characteristic of the intake system matched with the reference response characteristic of the intake system is saturated.

  As described above, the rising speed of the response characteristic of the intake system has a saturation characteristic (torque change rate saturation).

  Therefore, when the retardation correction based on the ignition timing is being performed, if the response characteristic of the intake system that is matched to the reference response characteristic of the intake system is saturated, the controller has a torque higher than the torque actually generated in the intake system. It will be recognized as occurring in the intake system. That is, the intake system torque reference value output from the intake system torque reference value calculation unit 122 is larger than the actual value.

  Then, when the torque change rate limiting unit 201 is not provided, the subtractor 125 subtracts an intake system torque reference value that is larger than the torque actually generated by the intake system from the torque command value of the ignition system. become.

  As a result, the ignition system F / B torque command value becomes small, and the torque reduction correction due to the retard of the ignition timing becomes small, so that the engine speed fluctuation becomes large.

  Therefore, in this embodiment, the torque change rate limiting unit 201 is provided in consideration of the saturation characteristics of the intake system, and the output of the torque change rate limiting unit 201 is used as the input to the subtractor 125.

  FIG. 9 is a diagram showing the rotational speed fluctuation of the engine 1 when the torque change rate limiting unit 201 is provided (solid line) and when it is not provided (broken line).

  As shown in FIG. 9, in the present embodiment in which the torque change rate limiting unit 201 is provided in the period from the time t11 to the time t12, when the retardation correction by the ignition timing is performed, the engine speed increases. And the rotational speed fluctuation can be reduced.

  It should be noted that the present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  For example, in the first embodiment, the response characteristic of the intake system is changed according to the engine rotational speed, but the response characteristic of the intake system may change according to the engine torque, the engine water temperature, etc. It may be changed accordingly.

It is a schematic block diagram of an engine idle control device. It is a block diagram explaining the idle control part of a controller. It is a block diagram which shows the detail of the F / B compensation part by 1st Embodiment. It is a table for setting the time constant T _qa of the transfer function Gp (s) indicating the response characteristic of the intake system. It is a flowchart explaining the idle control by 1st Embodiment. It is a flowchart explaining the calculation process of the F / B compensation part by 1st Embodiment. It is a time chart explaining idle control by a 1st embodiment. It is a block diagram which shows the detail of the F / B compensation part by 2nd Embodiment. It is the figure which showed the rotational speed fluctuation | variation of the engine when not providing (broken line) when a torque change rate restriction | limiting part is provided (solid line).

Explanation of symbols

1 engine 121 F / B control unit (target value calculation means)
122 Intake system torque reference value calculation unit (reference command value calculation means)
123 Phase compensator (dynamic characteristic compensation means)
124 Sign determination unit (response characteristic switching means)
125 Subtractor (torque correction value calculation means)
130 Ignition timing control unit (ignition timing control means)
140 Intake air amount control unit (intake air amount control means)

Claims (6)

An engine idle control device,
Target value calculating means for calculating a basic command value of an input to the controlled object according to the driving state of the vehicle;
Dynamic characteristic compensation means for calculating a phase compensation value based on the basic command value, including an inverse system of the response characteristic Gp (s) of the intake system and a reference response Gm (s) of the intake system;
Intake air amount control means for controlling the intake air amount of the engine according to the phase compensation value;
A normative command value computing means for computing a normative command value based on the basic command value and the standard response Gm (s) of the intake system;
A torque correction value calculating means having a deviation between the basic command value and the normative command value as a torque correction value;
Ignition timing control means for controlling the ignition timing of the engine according to the torque correction value;
When the torque correction value is a positive value, the reference response Gm (s) of the intake system is switched to a fast response characteristic, and when the torque correction value is a negative value, the reference response Gm (s) of the intake system is a slow response. Response characteristic switching means for switching to characteristics,
An engine idle control device comprising: 2. The engine idle control according to claim 1, wherein the dynamic characteristic compensation means uses the intake system response characteristic Gp (s) as an intake system response characteristic that changes in accordance with an operating state of the engine. 3. apparatus. 2. The engine idle control device according to claim 1, wherein the dynamic characteristic compensation means sets the response characteristic Gp (s) of the intake system to a faster response characteristic as the engine speed increases. When the torque correction value is a negative value, the response characteristic switching means is configured to prevent the intake system response characteristic Gp (s) matched with the intake system reference response characteristic Gm (s) from being saturated. The engine idle control device according to any one of claims 1 to 3, wherein the reference response Gm (s) of the system is switched to a slow response characteristic. 5. The normative command value calculation means, when the rate of change of the normative command value becomes a predetermined value or more, sets the predetermined value as a normative command value. An engine idle control device according to claim 1. 6. The engine idle control device according to claim 5, wherein the predetermined value is determined based on a saturation characteristic of the response characteristic Gp (s) of the intake system.

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