JP2001140679A - Output torque control device for internal combustion engine for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an output torque control device for internal combustion engine for vehicle capable of realizing a torque control considering a response characteristic of a vehicle for an increase/decrease of output torque, regarding a reducing technique of accelerating/decelerating shock. SOLUTION: In an output torque control device, a torque control routine is executed for every combustion cycle of an engine. In the torque control routine, the necessary/unnecessary of a torque control is decided, observing increased/decreased quantity ΔQ for basic injection quantity Q interlocking with an accelerating operation (step S10 to S16). In the torque control after the decision is formed, a control variable k is calculated based on speed and engine speed (step S18, S20). Not only a natural period of a driving system but also the number of stroke to which response delay due to bending of an engine mount is added is imparted to the value. The value of the control variable k is corresponding to limiting time on a control to limit an increase/ decrease of actual output torque for an increasing/decreasing change of requested output torque. By the stroke number, a fuel injection control is performed by correction injection quantity Qdmp (step S22 to S26).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output torque control device for an internal combustion engine for a vehicle, and more particularly, to a device for controlling an increase or a decrease in an engine torque within a predetermined period with respect to an increase or decrease in a required output torque. The present invention relates to a torque control technique for suppressing an acceleration / deceleration shock.

[0002]

2. Description of the Related Art Examples of this type of output torque control device are disclosed in Japanese Patent No. 2751571 and Japanese Patent No. 28612.
For example, a fuel injection device for a vehicle internal combustion engine described in Japanese Patent Publication No. 70-70 is cited. When the required injection amount changes from the first required injection amount to the second required injection amount to accelerate, these known fuel injection devices perform a preliminary injection first for a certain period of time, and thereafter,
The main injection is performed based on the second required injection amount. In such fuel injection control, when the torque of the internal combustion engine is input to the drive system, an input waveform for quickly converging the relative torsion angle without causing a transient displacement in the response of the torsional vibration system is obtained. A fuel injection pattern consisting of a preliminary injection and a main injection is executed according to the waveform.

[0003] According to these known fuel injection devices, the actual injection amount is controlled in accordance with the above-described injection pattern even when the required injection amount suddenly increases. Specifically, at the stage of the preliminary injection, a displacement corresponding to the convergent torsion angle is given to the drive system, and thereafter, when the main injection is started, the drive system maintains the convergent torsion angle and outputs the required output torque. To communicate. Therefore, it is considered that even when a sudden accelerator operation is performed, it is possible to smoothly shift to the acceleration state without exciting torsional vibration of the drive system.

[0004]

However, all of the above-mentioned known techniques merely focus on the torsional vibration of the drive system from the engine output shaft to the drive wheels. However, the response delay of the vehicle body vibration caused by the flexure of the engine mount and the like cannot be reflected in the control.

Further, in the prior art disclosed in the latter publication, the required injection amount is detected at predetermined detection timing (140 msec), and the above-described fuel injection patterns are sequentially superimposed on the basis of the detected required injection amount. Running. This control method is not suitable for controlling the output torque of the engine with high accuracy according to various acceleration / deceleration patterns, since the control timing is always uniform regardless of the operating state of the engine.

In view of the above-mentioned problems, the present invention can compensate for a delay in vehicle body vibration caused by a flexure of an engine mount and the like, and also enables more accurate engine output torque control. It is an object of the present invention to provide an output torque control device for an internal combustion engine for a vehicle.

[0007]

In order to achieve the above object,
An output torque control device for an internal combustion engine for a vehicle according to the present invention (claim 1) sets a control restriction period based on a traveling speed of a vehicle and a rotation speed of the internal combustion engine. Even if the required output torque increases or decreases rapidly, the increase or decrease of the actual output torque is limited to a smaller amount than the increase or decrease of the required output torque during this limited period. Is suppressed.

In a conventional control method, a time limit for control is generally set uniformly with reference to a natural period of a drive system. In the present invention, however, a response delay of vehicle body vibration due to bending of an engine mount or the like is reduced. To take this into account, the setting of the limit period is made variable according to the vehicle speed and the engine speed. In other words, although the natural period of the drive system is uniformly defined for each shift speed, the effect of a response delay on vehicle body vibration caused by flexure of the engine mount and the like differs depending on the degree of acceleration / deceleration actually required. Such a difference in the effect of the response delay can be approximately determined on the basis of the parameters of the vehicle speed and the engine speed. Therefore, the correspondence between these parameters and the limit period must be defined in advance by a control map or the like. If this is the case, fine output torque control according to the running state can be performed. On the other hand, since the traveling vehicle speed and the rotation speed of the engine are highly related to the gear stage actually selected, the setting of the limit period according to the present invention does not deviate from the relationship with the natural period of the drive system.

Further, an output torque control device for an internal combustion engine for a vehicle according to the present invention (claim 2) executes output torque control for suppressing acceleration / deceleration shock every combustion cycle of the internal combustion engine. In this case, since the output torque control is performed in synchronization with the stroke of the engine, fine control can be realized correspondingly, and acceleration / deceleration shock can be effectively suppressed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention can be embodied as an output torque control device of a vehicle diesel engine, for example, and a specific example is shown in FIG. Referring to FIG. 1, an engine 1 includes an electronically controlled fuel injection pump 2, and a fuel injection pump 2 further includes a linear actuator 4 for changing the position of its control sleeve.
It has. A fuel injection valve 6 is connected to the fuel injection pump 2 for each cylinder of the engine 1, and the amount of fuel injection by the fuel injection valve 6 is varied according to the operation amount of the control sleeve position.

The crankshaft 8 of the engine 1 is connected to a transmission 10 via a clutch (not shown).
Further, it is connected to driving wheels of a vehicle, that is, a driving system through a propeller shaft 12 and a differential gear (not shown). The drive of the linear actuator 4 described above is controlled by an electronic control unit (ECU) 14. The ECU 14 outputs an operation signal CSP described later to the linear actuator 4 to adjust the position of the control sleeve of the fuel injection pump 2. The fuel injection amount from each fuel injection valve 6 can be controlled as desired.

On the other hand, various sensors are connected to the ECU 14. These sensors include a crank angle sensor 16 that outputs a crank angle signal CA synchronized with the rotation of the crankshaft 8, and an output shaft of the transmission 10. There are a vehicle speed sensor 18 that outputs a vehicle speed pulse signal V having a cycle corresponding to the rotation speed, an accelerator opening sensor 22 that detects an opening APS of an accelerator pedal 20 of the vehicle, and the like. The ECU 12 is connected to other sensors and actuators (not shown), and controls, for example, the injection timing of the fuel injection pump 2.

The ECU 14 has a program for controlling the torque of the engine 1 built therein. The torque control device according to the present embodiment controls the engine 1 according to the control program.
Can be specifically executed.

[0014]

Referring to FIG. 2, there is shown an output torque control routine executed by the ECU 14 as the above-described control program. Hereinafter, an embodiment of the output torque control according to the present invention will be described with reference to this flowchart. In this embodiment, the ECU 14 executes the control routine of FIG. 2 in synchronization with the stroke of the engine 1. That is, E
The CU 14 executes this control routine using the combustion cycle of the engine 1 as a control cycle.

First, in step S10, sensor signals from the various sensors described above are read, and in the next step S12, a basic injection amount Q is calculated based on these sensor signals. The basic injection amount Q can be obtained, for example, based on the accelerator opening APS and the engine speed Ne obtained from the sensor signal. The value of the basic injection amount Q obtained in this way can be used as it is for basic fuel injection control by the ECU 14, and the ECU 14 determines the corresponding linear actuator 4 according to the basic injection amount Q for each combustion cycle of each cylinder. To output an operation signal CSP to control the operation amount of the control sleeve of the fuel injection pump 2. In this case, the fuel injection amount is controlled to increase or decrease in conjunction with the accelerator operation by the driver, and the engine 1 can exhibit the actual output torque according to the required output torque.

The above is the basic output torque control method by the ECU 14. In the following control routine, the value of the basic injection amount Q is positively corrected, and the actual output torque is controlled with respect to the increase or decrease of the required output torque. By limiting the amount of increase or decrease in the output torque, the acceleration / deceleration shock of the vehicle is suppressed. That is, after obtaining the basic injection amount Q in step S12 described above, the ECU 14 observes the variation ΔQ of the basic injection amount Q in step S14. Here, the change amount ΔQ is defined by the following equation as a control amount change for each combustion cycle (stroke n).

ΔQ (n) ≡Q (n) −Q (n−1) (1) In the next step S16, it is determined whether or not correction of the basic injection amount Q is to be started. This determination can be made, for example, by setting a start determination threshold value for the change amount ΔQ in advance and comparing the threshold value with the change amount ΔQ. In addition, as for the setting of the threshold value, for example, a value of ΔQ that can be considered to cause an increase or decrease of the output torque according to the change amount ΔQ to cause an acceleration / deceleration shock of the vehicle can be set in advance as the threshold value.

If the start determination is made in step S16 (Yes), step S18 is executed next. On the other hand, if the determination is not made (No), it is determined that the vehicle is in a steady running state and step S18 is performed. Without executing the subsequent steps, the torque control routine returns here in preparation for the next combustion cycle. If the above judgment is satisfied,
In step S18, the vehicle speed V and the engine speed Ne are input to the calculation circuit, and in the next step S20, the control variable k is calculated based on the parameters of the vehicle speed V and the rotation speed Ne.

More specifically, the specific value of the control variable k corresponds to the setting of a predetermined control restriction period in which the increase or decrease of the actual output torque is to be limited with respect to the increase or decrease of the required output torque. This limit period is, for example, the natural period of the drive system is set to T
In this case, it can be set as T / 2 + α. However, as described above, in order to transmit the increase or decrease in the engine torque to the vehicle body, the response delay of the vehicle body vibration due to the deflection of the engine mount or the displacement of the backlash is taken into consideration. And α represents the delay time.

In the present control routine, the control variable k is defined as a value including one half of the natural period T and the delay time α. Can be. The map of FIG. 3 uses the vehicle speed V and the engine rotation speed Ne as arguments, and gives the corresponding number of strokes on the map as the value of the control variable k. Also,
The map characteristic of FIG. 3 shows that the value of the control variable k is set smaller as the vehicle speed V is in the higher speed range and the rotation speed Ne is in the lower rotation range, while the vehicle speed V is in the lower speed range and the rotation speed is higher. In the range, the value of the control variable k is set large. Also,
If the value of the control variable k actually obtained by the map interpolation includes a fraction below the decimal point, the ECU 14 rounds down,
The obtained numerical value is converted to an integer by processing such as rounding up or rounding off.

Next, at step S22, a correction injection amount Qdmp for the basic injection amount Q is calculated. Here, the correction injection amount Qdmp (n) for each combustion cycle can be defined by the following equation, for example, according to a predetermined correction pattern. Qdmp (n) ≡Qdmp (n−1) + K {ΔQ (n) + ΔQ (nk)} (2) where K = 0.5 in equation (2), and Qdmp (0) = Q
(0), when n−k ≦ 0, ΔQ (n−k) = 0. In addition,
The coefficient K is a coefficient for adjusting the feeling of acceleration, deceleration, and the like in the actual vehicle, and can be adjusted as desired according to the characteristics of the vehicle with reference to 0.5.

After calculating the corrected injection amount Qdmp (n) as described above, the ECU 14 proceeds to the next step S24, and controls the actual fuel injection amount with the obtained corrected injection amount Qdmp (n). FIG. 4 shows the relationship between the change in the basic injection amount Q and the corrected injection amount Qdmp in the same column, for example, during acceleration. In this case, the above-described correction process is started when the driver starts depressing the accelerator pedal 20 and the variation ΔQ of the basic injection amount Q exceeds the determination threshold (stroke n = 1).
Therefore, the correction injection amount Qdmp in the subsequent combustion cycle
The value of (n) is limited with respect to the basic injection amount indicated by the two-dot chain line in the figure.

Such calculation of the correction injection amount Qdmp is repeated until the correction end determination is made in the next step S26. In step S26, after the transition period of the basic injection amount Q (stroke n = 1 to 7) has elapsed and the combustion cycle (= k) corresponding to a predetermined limit period has elapsed, the correction end determination is established. At this time, the ECU 14 terminates the torque control routine and executes the next combustion cycle (stroke n = 1).
The process shifts from 1) to the normal fuel injection control mode. In addition,
In the example of FIG. 4, the control variable k is set to three strokes.

By executing the torque control routine of the present embodiment, for example, when the required output torque of the engine 1 increases with acceleration of the vehicle, the increase ΔQ of the basic injection amount Q for each combustion cycle. On the other hand, in the number of strokes (= k, k _1,2 ) corresponding to the limited period, the actual injection amount is limited to the corrected injection amount Qdmp, and after the number of strokes corresponding to the limited period, the limitation is released. . By executing such injection amount correction processing sequentially for each combustion cycle (steps S22 and S24), an acceleration shock accompanied by a longitudinal vibration of the vehicle body is obtained as a result of superimposing the longitudinal acceleration responses to individual torque changes. Is suppressed.

Further, in steps S18 and S20,
Since the control variable k is calculated using the traveling vehicle speed V and the engine rotation speed Ne as parameters, and the control restriction period is set based on these parameters, fine setting according to the traveling state of the vehicle and the acceleration / deceleration pattern can be performed. Is possible,
The effect of the response delay of the vehicle body vibration due to the bending of the engine mount or the like can be reflected in the control of the output torque. Further, the relationship between the vehicle speed range and the engine speed range can be added to the map characteristics shown in FIG. 3 so that the specific value of the set control variable k is determined by the specific value of the drive system. The relationship with the cycle T is not lost.

Further, since the ECU 14 executes the present torque control routine in each combustion cycle in synchronization with the stroke of the engine 1, torque control can be realized with high accuracy. Note that the above-described torque control routine can be executed by rewriting the correction pattern, and an example is shown in FIG.

In the example of FIG. 5, the correction injection amount Qdmp (n) is defined by the following equation (5) according to the second correction pattern. Qdmp (n) ≡Qdmp (n-1) + {ΔQ (n) −ΔQ (nk− ₁ ) + ΔQ (nk− ₂ )} (5) where Qdmp (0) = Q (0), n− When k _1,2 ≦ 0, ΔQ (n−
k _1,2 ) = 0. Further, step S2 of the control routine
At 0, two types of control variables k ₁ and k ₂ are set. These control variables k ₁ and k ₂ are theoretically thought to correspond to 1/6 and 1/3 of the drive system natural period, respectively. However, in consideration of the above-mentioned response delay α,
The number of steps is set to 1/6, 1/3 or more. Further, in this case, the ECU 14 stores the control variable k
For each _1, k _2, is intended to comprise the map.

Even in the case of FIG. 5, the correction injection amount Q for each combustion cycle starts from the time when the correction is started (stroke n = 1).
The value of dmp (n) (solid line) is limited with respect to the basic injection amount Q (two-dot chain line). On the other hand, the calculation of the correction injection amount Qdmp is
After the transient change period of the basic injection amount Q (stroke n = 1 to 7) has elapsed, the combustion is performed until the combustion cycle (= k ₂ ) corresponding to the limit period has elapsed. In this case, the next combustion cycle (stroke n) = 10), the mode shifts to the normal fuel injection control mode. In the example of FIG. 5, the control variable k ₁ = 1 stroke, k ₂ = 2
Each is set for the journey.

The above is an example of the case where the present control routine is executed during acceleration, but it goes without saying that the torque control routine of the present embodiment also functions effectively in the case of deceleration. If the correction start and end determinations are not particularly made in the torque control routine, steps S16 and S26 can be omitted. Even when these determinations are not made, the normal fuel injection control mode can be executed by calculating the injection amount for each combustion cycle using the above-described arithmetic expressions (2) and (3).

[0030]

According to the output torque control device for an internal combustion engine for a vehicle according to the present invention (claim 1), torque control can be performed in consideration of the response characteristics of the vehicle, and acceleration / deceleration shocks can be efficiently suppressed. In the output torque control device of the present invention (claim 2), the control cycle and the combustion cycle are synchronized, and the control method is extremely rational. Therefore, high-accuracy control is realized, which greatly contributes to effective suppression of acceleration / deceleration shock.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a torque control device according to an embodiment.

FIG. 2 is a flowchart showing a torque control routine.

FIG. 3 is an example of a map used for calculating a control variable.

FIG. 4 is a time chart showing a relationship between a change in a basic injection amount and a correction injection amount in comparison.

FIG. 5 is a time chart showing an example of a different correction pattern from FIG. 4;

[Explanation of symbols]

 Reference Signs List 1 engine 2 fuel injection pump 4 linear actuator 6 fuel injection valve 14 ECU 16 crank angle sensor 18 vehicle speed sensor

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 3G084 AA01 BA13 CA04 CA05 CA06 CA09 DA11 EA11 EB04 EB08 EC03 FA05 FA13 FA32 FA33 3G301 HA02 JA04 KA12 KA16 KA21 KA25 KB04 LB15 MA11 NA08 NB14 NB18 NC02 NC06 NE17 NE19 NE01Z02Z

Claims (2)

[Claims] When a required output torque for an internal combustion engine increases or decreases by a predetermined amount or more, a vehicle is controlled by limiting the increase or decrease of the actual output torque to the increase or decrease of the required output torque within a predetermined limit period. An output torque control device for an internal combustion engine for a vehicle, which suppresses an acceleration / deceleration shock of the vehicle, wherein the limit period is set based on a traveling vehicle speed of the vehicle and a rotation speed of the internal combustion engine. apparatus. 2. When the required output torque for the internal combustion engine increases or decreases by a predetermined amount or more, output torque control for limiting the increase or decrease of the actual output torque to the increase or decrease of the required output torque within a predetermined limit period is performed. An output torque control device for an internal combustion engine for a vehicle, wherein the output torque control is executed for each combustion cycle of the internal combustion engine. .