JP2000064894A - Torque control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a problem such as reduction in drivability or fuel deterioration, and to previously prevent a back-and-forth oscillation of a vehicle caused by a rapid torque change. SOLUTION: The increase and decrease of fuel injection quantity Q controlled by an accelerator pedal operation of a driver are restricted in restricted injection quantity Q dmp, and the restriction is released after time limit T dmp established on the basis of a characteristic frequency of a vehicular driveline. The increase and decrease of the fuel injection quantity Q are conducted after the time limit T dmp, and operates in a direction where a vehicular acceleration generated by a first increase of engine torque and a second increase of the engine torque are canceled out each other.

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a torque control device for an internal combustion engine, and more particularly, to preventing a longitudinal vibration of a vehicle caused by a sudden accelerator operation. The present invention relates to a torque control device. 2. Description of the Related Art It has been confirmed that a sudden increase or decrease in engine torque caused by a sudden accelerator operation by a driver causes longitudinal vibration in a running vehicle.
This phenomenon is caused by a sudden change in the engine torque, such as the drive system of the vehicle (for example, a propeller shaft or drive shaft).
This is generated when torsional vibration is excited. Taking acceleration as an example, as shown in FIG. 7, a change in the acceleration of the vehicle occurs in the natural cycle of the drive system with an increase in the engine torque, and this change gives the driver discomfort. Therefore, as a main countermeasure, for example,
In the diesel engine described in No. 091, even when the accelerator is suddenly depressed, the control sleeve is operated slowly to prevent a sudden increase in engine torque, thereby avoiding the occurrence of torsional vibration. are doing. [0003] However, in the above-described measures, the response of rising and falling of the engine torque is deliberately degraded, so that at the time of acceleration, a feeling of acceleration corresponding to the accelerator operation is obtained. This leads to a decrease in drivability, and furthermore, at the time of deceleration, there is an adverse effect that unnecessary fuel injection is continued to cause deterioration of fuel efficiency. An object of the present invention is to prevent the longitudinal vibration of a vehicle due to a change in torque of an internal combustion engine caused by a sudden accelerator operation, while avoiding adverse effects such as a decrease in drivability and a decrease in fuel efficiency. An object of the present invention is to provide a torque control device for an internal combustion engine. In order to achieve the above object, according to the present invention, a fuel injection amount controlled according to a torque required for an internal combustion engine is increased or decreased by a predetermined amount by an injection amount correcting means. And the restriction is released after a lapse of a limit time set based on the natural frequency of the drive system of the vehicle. For this reason, the increase or decrease in the fuel injection amount is performed in a divided manner with a time limit, and the change in the acceleration of the vehicle caused by the first increase or decrease in the engine torque occurs in the natural cycle of the drive system of the vehicle. , Since the change in the acceleration of the vehicle caused by the second increase or decrease in the engine torque is caused to act in a cycle that offsets the previous change in the acceleration,
The change in the acceleration is quickly suppressed, and the increase / decrease in the fuel injection amount is merely divided, but the substantial response of the engine torque is not slowed down. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment in which the present invention is embodied in a torque control device for a diesel engine will be described below. The diesel engine of the present embodiment is configured as an electronically controlled type in which the sleeve position is driven by an actuator to control the fuel injection amount. As shown in FIG. 1, the engine 1 is provided with a fuel injection pump 2 from which high-pressure fuel is discharged in synchronization with the rotation of the engine 1. A fuel injection valve 3 of each cylinder is connected to the fuel injection pump 2, and high-pressure fuel from the injection pump 2 is injected into the combustion chamber of the engine 1 from each fuel injection valve 3 and burns to rotate the crankshaft 7. The control sleeve (not shown) of the fuel injection pump 2 is driven and operated by the actuator 4, and the fuel injection amount is controlled in accordance with the operation amount to adjust the engine output. Engine 1
Is connected to driving wheels of the vehicle via a propeller shaft 6 and a differential gear (not shown), and the rotation of the engine 1 is controlled by the transmission 5.
Is decelerated in accordance with the shift speed of the vehicle and transmitted to the drive wheels as a driving force. In the passenger compartment, an input / output device (not shown), a storage device (ROM, RAM, BURAM, etc.) for storing control programs and control maps, etc., and a central processing unit (C)
An ECU (engine control unit) 10 including a PU (Public Input Unit), a timer counter, and the like is installed to perform overall control of the engine 1. On the input side of the ECU 10, a crank angle sensor 11 for outputting a crank angle signal synchronized with the rotation of the crankshaft 7 of the engine 1, and a vehicle speed for outputting a vehicle speed pulse signal having a cycle corresponding to the rotation speed of the output shaft of the transmission 5 Sensor 1
2. An accelerator opening sensor 14 as torque detecting means for detecting the opening APS of the accelerator pedal 13 of the vehicle is connected, and the control sleeve operating actuator 4 is connected to the output side. Note that the ECU 1
In addition, various sensors and actuators are connected to 0 to control, for example, the injection timing of the fuel injection pump 2. Next, torque control performed by the ECU 10 of the torque control device for a diesel engine configured as described above will be described. First, an outline of a basic control procedure of the fuel injection amount will be described. As is well known, the basic injection amount Q is set based on the engine rotation speed Ne and the accelerator opening APS, and the control sleeve is controlled by the actuator 4 accordingly. Is controlled. In FIG. 4, the basic injection amount Q is indicated by a broken line.
When the driver operates the accelerator pedal 13 in the opening direction to accelerate, the basic injection amount Q increases from the value Qst at the start of the opening operation to the value Qen at the end. When the accelerator pedal 13 is operated in the closing direction to decelerate, the basic injection amount Q decreases from the value Qst at the start of the closing operation to the value Qen at the end. If the accelerator operation at this time is performed instantaneously (for example, about 0.1 sec), the engine rotation speed Ne hardly changes during that time, but the basic injection amount Q is sequentially set depending on the change in the accelerator opening APS. Therefore, it rapidly increases or decreases. The above is a general procedure for setting the basic injection amount Q. In addition, in the present embodiment, the basic injection amount Q thus set is corrected by the torque control routine shown in FIGS. I have. In FIG. 4, the change in the corrected basic injection amount Q is represented by a solid line. And in this embodiment,
The ECU 10 for setting the general basic injection amount Q
Functions as injection amount control means, and the ECU 10 when executing the torque control routine functions as injection amount correction means. The procedure will be described below. The ECU executes a routine shown in FIG.
ms). First, in step S2, a detection signal is input from each of the above-described sensors, and in step S4, a change rate ΔQ of the basic fuel injection amount Q set in advance based on the accelerator opening APS and the engine rotation speed Ne is calculated. The acceleration determination injection amount change rate ΔQAcc and the deceleration determination injection amount change rate ΔQdec are compared. If the change rate ΔQ is equal to or greater than the acceleration determination injection amount change rate ΔQAcc, it is determined that the vehicle is in an accelerating state with the opening operation of the accelerator pedal 13 and the process proceeds to step S6. It is determined that the vehicle is in the deceleration state following the closing operation of 13, and the process proceeds to step S24. At the time of acceleration shown in FIG. 4, the ECU 10 proceeds to step S6 to change the current gear position of the transmission 5 based on the engine speed Ne obtained from the crank angle signal and the vehicle speed Vs obtained from the vehicle speed pulse signal. presume. Then
In step S8, the limited injection amount Qdmp and the limited time Tdmp are set. Here, the limited injection amount Qdmp is 1/1 of a value obtained by subtracting the injection amount Qst at the start of the accelerator opening operation from the injection amount when the accelerator opening APS is fully opened at the current engine rotation speed Ne (fully opened injection amount). It is set as a value obtained by adding the injection amount Qst to 2. This is because acceleration in which the vibration of the vehicle is a problem is in a relatively low rotation range, and there is room for increasing the engine rotation speed Ne when accelerating in the low rotation range. Therefore, the injection amount Qen at the end of the accelerator opening operation Can be assumed to apply a substantially full-open injection quantity. That is, the limited injection amount Qdm
p is the injection amount at the start of the accelerator opening operation, which is 噴射 of the change amount (Qen-Qst) between the injection amount Qst at the start of the accelerator opening operation and the injection amount Qen at the end of the accelerator opening operation, that is, the substantially full injection amount It is set to a value obtained by adding the quantity Qst. The time limit Tdmp is given by T / 2 + α, where T is the longitudinal vibration cycle of the vehicle caused by a sudden change in the engine torque (the above-described natural cycle), assuming the current gear position obtained in step S6. Is set as As described in the related art, the longitudinal vibration of the vehicle due to the sudden change in torque is generated by exciting the torsional vibration in the drive system, and its natural frequency depends on the specification of the vehicle and the gear ratio (the gear position of the transmission 5). And final reduction ratio). Since the specifications of the vehicle and the final reduction ratio are known in advance, the vibration cycle that may occur in the vehicle can be specified based on the current gear position. Further, in order to transmit a sudden change in the engine torque to the vehicle, it is necessary to take into account a response delay due to the bending of the engine mount, and α is a correction coefficient for the response delay. In consideration of the above, a map in which the limit time Tdmp is set in advance for each shift speed is prepared, and in step S8, the limit time Tdmp is set based on this map. It should be noted that the higher the shift speed, the shorter the vibration period T, so that the time limit Tdm
p is also set to a small value. Next, in step S10, it is determined whether or not the basic injection amount Q has exceeded the above-described limit injection amount Qdmp.
Since the basic injection amount Q does not exceed the limited injection amount Qdmp at the beginning of the acceleration, a NO (No) determination is made in step S10, and the process proceeds to step S12. ECU10
Increments the counter t1 in step S12,
In step S14, it is determined whether a time limit Tdmp has elapsed from the start of acceleration. Initially, the time limit Tdmp has not elapsed, so that the determination is NO, the process returns to step S10, and the processes of steps S10 to S14 are repeated. Therefore, during this period ab, the correction of the basic injection amount Q by the torque control routine is not performed, and the basic injection amount Q increases in accordance with the increase in the accelerator opening APS. The basic injection amount Q is equal to the limited injection amount Qdmp.
Is exceeded, and a determination of YES (affirmation) is made in step S10, the ECU 10 proceeds to step S16, sets the limited injection amount Qdmp as the basic injection amount Q, and after the limited time Tdmp elapses, the ECU 10 determines YES in step S14. Until you make a decision,
Step S16 is repeated. Therefore, in this period bc, the basic injection amount Q continues to be limited to the limited injection amount Qdmp. When the time limit Tdmp has elapsed and the determination in step S14 is YES, in step S18, the increase rate ΔQopn of the basic injection amount Q in the period ab in accordance with the following equation:
And the basic injection amount Q is sequentially set in the increasing direction according to the increase rate ΔQopn. ΔQopn = (Qdmp−Qst) / t1 In step S20, it is determined whether or not the basic injection amount Q set in the increasing direction has reached the value Qen at the end of the accelerator opening operation, and a determination of YES is made. Is repeated, the process of step S18 is repeatedly executed. Therefore, in the period cd, the increase rate of the basic injection amount Q in the period ab is reproduced. The basic injection amount Q is the value Q at the end of the opening operation
When en is reached and the determination in step S20 is YES, the counter t1 is reset in step S22, and this routine ends. On the other hand, during deceleration, the ECU 10 proceeds to step S
4 to step S24, and the current gear position of the transmission 5 is estimated as in step S6. Further, step S
In step 26, 1/2 of the value Qst at the start of the accelerator closing operation is set as the limited injection amount Qdmp. That is, the accelerator pedal 13 at the time of deceleration is almost fully operated to reach the fuel cut region, so that the value Qen at the end of the accelerator closing operation is obtained.
Can be estimated to be zero. Therefore, the limited injection amount Qdm
It can be considered that p is set to の of the variation width of the basic injection amount Q at the start of the accelerator closing operation. In step S26, the vibration period T / 2 + α of the vehicle is set as the time limit Tdmp on the premise of the current gear position as in the case of acceleration. Next, at step S28, it is determined whether or not the basic injection amount Q has fallen below the limited injection amount Qdmp.
In the case of O, the counter t2 is incremented in step S30, and in step S32 the time limit Tdm from the start of deceleration is set.
It is determined whether or not p has elapsed. YE in step S28
If the determination of S is made, the ECU 10 proceeds to step S34 to set the limited injection amount Qdmp as the basic injection amount Q. If the limited time Tdmp has elapsed and the determination of step S32 is YES, the process proceeds to step S36. . Therefore, as shown in FIG. 4, the basic injection amount Q decreases in accordance with the accelerator opening APS during the initial period ef at the start of deceleration, and is limited to the limited injection amount Qdmp during the subsequent period fg. to continue. Further, in step S36, the ECU 10 obtains the decrease rate ΔQclos of the basic injection amount Q in the period ef according to the following equation, and sequentially sets the basic injection amount Q in the decreasing direction according to the decrease rate ΔQclos. Therefore, in the period gh,
The reduction rate of the basic injection amount Q in the period ef is reproduced. Thereafter, when the basic injection amount Q reaches the value Qen at the end of the closing operation in step S38, the counter t2 is reset in step S40, and this routine ends. ΔQclos = Qdmp / t2 When the basic injection amount Q is corrected as described above, the longitudinal vibration (represented as acceleration G in FIG. 4) generated in the vehicle changes as follows. During acceleration, when the basic injection amount Q starts to rapidly increase from the value Qst due to the opening operation of the accelerator pedal 13, as shown in FIG. 4, due to the increase in engine torque, the acceleration G of the vehicle is delayed by α (engine mount). (Due to the flexure of the body). When the torque control of the present embodiment is not used, the basic injection amount Q is, as shown by the broken line, the injection amount Q at the start of the accelerator opening operation.
From st to the injection amount Qen at the end of the opening operation, it increases in accordance with the change in the accelerator opening, and the change in the acceleration G at this time changes with a large amplitude as shown by the broken line. However, when the torque control of the present invention is used, as shown by the solid line in FIG. (The value obtained by adding the start injection amount Qst)
At the time point when the acceleration G is reversed (point c in FIG. 4) after the limit time Tdmp (1/2 + α of the vibration period T of the vehicle) elapses and the basic injection amount Q at the beginning of acceleration is maintained.
Is reproduced and reaches the value Qen at the end of the opening operation.
Since the engine mount continues to bend in the same direction during this time, after the lapse of the time limit Tdmp, the engine torque is transmitted to the drive wheel side with the increase of the basic injection amount Q without delay of α. That is, in response to the change in the acceleration G of the vehicle caused by the first increase in the engine torque (indicated by a two-dot chain line in FIG. 4), the second change in the acceleration (point c in FIG. 4) Since the change in the acceleration G (indicated by the solid line) due to the increase in the engine torque acts to cancel each other, the fluctuation in the total acceleration G (indicated by the thick solid line) can be quickly suppressed in almost half a cycle. Also, at the time of deceleration, since the same is true except that the basic injection amount Q and the acceleration G change in opposite directions,
The fluctuation of the acceleration G can be suppressed promptly. Therefore, it is possible to reliably and promptly suppress the longitudinal vibration generated in the vehicle due to the acceleration and deceleration, thereby avoiding a situation in which the driver is uncomfortable. In order to cancel the acceleration G as described above, the accelerator opening is limited to about 2/5 to 3/5 with respect to the limited injection amount Qdmp about 1/2 of the variation width of the basic injection amount Q. The value obtained by adding the injection amount Qst at the start of the operation or the closing operation is desirable. Regarding the time limit Tdmp, 1/2 to 3 /
About 4 is desirable. In addition, increase rate ΔQopn and decrease rate ΔQclo
Although it is not necessary to completely reproduce s, it is desirable to set s to be an approximate increase / decrease situation. On the other hand, as is apparent from FIG. 3, the increase rate ΔQopn and the decrease rate ΔQclos of the basic injection amount Q are exactly the same as when the control is performed in accordance with the normal accelerator opening APS. In this case, the increase / decrease of the basic injection amount Q is simply divided into two. As a result, the substantial rise and fall responsiveness of the engine torque hardly slows down as compared with the case of the normal control, so that a sharp feeling of acceleration can be obtained at the time of acceleration and good drivability can be provided. In addition, when decelerating, fuel consumption can be efficiently reduced by prompt fuel cut. Second Embodiment Next, a second embodiment in which the present invention is embodied in a torque control device for a diesel engine will be described. The configuration of the torque control device of the present embodiment is the same as that of the first embodiment, and the difference lies in the content of torque control during acceleration. Therefore, differences will be mainly described. The correction of the basic injection amount Q by the torque control is as follows.
This is performed by a torque control routine shown in FIG. 5, and in this embodiment, the ECU 10 at the time of executing this routine functions as an injection amount correction unit. The ECU 10 proceeds to step S
At 42, a detection signal is input from each sensor, and the
And the change rate ΔQ of the basic injection amount Q and the change rate Δ
By comparing QAcc and the deceleration determination injection amount change rate Δdec, it is determined whether the vehicle is in an acceleration, deceleration, or steady state. When accelerating, the process proceeds to step S46, and when decelerating,
The same processing (not shown) as in step S24 and subsequent steps of the first embodiment is executed, and this routine is temporarily terminated in a normal state. When the process proceeds to step S46 as acceleration, the ECU 10 estimates the current gear position based on the engine speed Ne and the vehicle speed Vs, and sets a time limit Tdmp in step S48. Although details will not be described, the processing in step S48 is the same as that in step S8 in the first embodiment. Next, in step S50, the basic injection amount Q is set according to the following equation. Q = (QAPS-Qst) K + Qst Here, QAPS is the basic injection amount before correction, which is Qst before acceleration and Qen after acceleration. K is a correction coefficient, and in this embodiment, 0.5 is applied. Then, in step S52, the basic injection amount QAP based on the accelerator opening APS
The rate of change ΔQAPS of S is the rate of change Δ
Acceleration end judgment value Δ set as a value smaller than QAcc
It is determined whether it is equal to or less than Q2. If the determination is NO, it is determined that the vehicle is still accelerating, the counter t3 is incremented in step S54, and it is determined in step S56 whether the time limit Tdmp has elapsed from the start of acceleration. Since the time limit Tdmp has not elapsed at the beginning, the process returns to step S50, and the processes of steps S50 to S54 are repeated. That is, by the processing in step S50, the increase rate ΔQopn of the basic injection amount Q in the period ij in FIG. 6 is limited to の of the change rate ΔQAPS based on the accelerator opening APS. When the driver's accelerator operation in the opening direction is stopped and the rate of change .DELTA.QAPS becomes equal to or less than the acceleration end determination value .DELTA.Q2, it is determined that the acceleration has ended, and the flow proceeds to step S58 to set the setting completion flag F Is set or not. Since the setting completion flag F is not set at first, the process proceeds to step S60, the basic injection amount Q at that time is set as the intermediate injection amount Qm, and the setting completion flag F is set in step S62. Thereafter, when the process again proceeds to step S58, the setting completion flag F is set, so that the process proceeds to step S56 without repeating the process of step S60. The process of step S50 is repeated as long as the time limit Tdmp does not elapse even after the end of acceleration.
In the period jk, the increase rate ΔQopn of the basic injection amount Q is limited to, for example, about １ ／ as in the period ij before that. In a typical acceleration state shown in FIG. 6, the accelerator opening AP
Since S is kept substantially constant, the increase rate ΔQop during this time
When n becomes 0, the basic injection amount Q becomes the accelerator opening APS
Is maintained substantially constant at a value obtained by adding the injection amount Qst at the start of the accelerator opening operation to 1/2 of the change width based on the above. Thereafter, when the time limit Tdmp has elapsed and the determination of YES is made in step S56, the setting completion flag F is reset in step S64, and in step S66, the basic injection amount Q in the period k-1 is increased according to the following equation. The rate ΔQopn is obtained, and the basic injection amount Q is sequentially set in the increasing direction according to the rate of increase ΔQopn. ΔQopn = (Qm-Qst) / t3 Until it is determined in step S68 that the basic injection amount Q has reached the value Qen at the end of the accelerator opening operation, the processing in step S66 is repeated, and the basic injection in the period ij is performed. The increase in the quantity Q is reproduced in the period k-1. Thereafter, the counter t3 is reset in step S70, and this routine ends. As is apparent from the above description, the feature of the torque control of this embodiment is that the rate of increase ΔQopn of the basic injection amount Q in the period ij and the period k-1 is limited. That is, in the first embodiment, the injection amount Q at the end of the accelerator opening operation
Although the limited injection amount Qdmp is set on the assumption that en is the full-open injection amount, it does not always apply to all accelerations due to the presence of various patterns of acceleration. This limits the rate of increase ΔQopn. Then, as in the first embodiment, the change in the acceleration G of the vehicle caused by the first increase in the engine torque is reduced by two.
Since the change is offset by the change in the acceleration G caused by the second increase in the engine torque, the change in the total vehicle acceleration G (indicated by a thick solid line in FIG. 6) can be suppressed promptly, thereby giving the driver discomfort. The situation can be avoided beforehand. As is apparent from FIG. 6, although the increase rate ΔQopn of the basic injection amount Q is limited to 比較 as compared with the first embodiment, the responsiveness of the engine torque to rise is intentionally reduced. Compared with the conventional example, the response is much better. Therefore, a sharp feeling of acceleration can be obtained during acceleration, and good drivability can be provided. Although the description of the embodiments has been completed above, embodiments of the present invention are not limited to these embodiments. For example,
In the first embodiment and the second embodiment, the engine torque is controlled by correcting the injection amount Q of the fuel injection pump 2 by realizing the electronic control type torque control device for the diesel engine. In the case of a diesel engine using a pump, the position of the control sleeve of the pump may be controlled, or in the case of a diesel engine using a time-controlled injection system, the injection time may be controlled. The present invention is not limited to a diesel engine as long as it has a sufficient control response, and may be embodied as, for example, a gasoline engine described in JP-A-8-313396.
In this case, even if the estimated target load value (average effective pressure) correlated with the torque of the internal combustion engine is controlled, the same operation and effect as in the above embodiment can be obtained. As described above, according to the torque control device for an internal combustion engine of the present invention, the increase or decrease of the fuel injection amount when the accelerator opening is suddenly changed is divided and performed with a time limit. Therefore, the second increase / decrease of the engine torque acts in a direction to offset the acceleration of the vehicle caused by the first increase / decrease of the engine torque. The vehicle's longitudinal vibration can be prevented beforehand, and the responsiveness of the engine torque is not slowed down only by dividing the increase or decrease in the fuel injection amount. In addition to providing good drivability, the fuel efficiency can be efficiently reduced by a quick fuel cut during deceleration.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall configuration diagram showing a diesel engine torque control device according to a first embodiment. FIG. 2 is a flowchart illustrating a torque control routine. FIG. 3 is a flowchart illustrating a torque control routine. FIG. 4 is a time chart showing a control state of a basic injection amount. FIG. 5 is a flowchart illustrating a torque control routine according to a second embodiment. FIG. 6 is a time chart showing a control state of a basic injection amount. FIG. 7 is a time chart showing a change in engine torque during acceleration and a change in acceleration of the vehicle accompanying the change. [Description of Signs] 10 ECU (injection amount control means, injection amount correction means) 14 Accelerator opening sensor (torque detection means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F02D 41/10 380 F02D 41/10 380B 41/12 380 41/12 380A 380B 41/40 41 / 40F ( 72) Inventor Yoshihisa Iwanaga 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (72) Inventor Seiji Akiyoshi 5-33-8 Shiba 5-chome, Minato-ku, Tokyo Mitsubishi Motors Corporation F-term (Reference) 3G084 AA01 BA13 CA04 CA06 DA39 EA05 EA11 EB08 EB12 EC01 EC04 FA05 FA10 FA32 FA38 3G301 HA02 JA37 KA12 KA16 LB14 LB15 MA14 NB03 NC02 ND03 NE18 NE23 PA11Z PE03Z PE06Z PF01Z

Claims (1)

Claims: 1. A torque detecting means for estimating or detecting a torque required of an internal combustion engine, and a fuel injection amount of the internal combustion engine is controlled based on the torque estimated or detected by the torque detecting means. An injection amount control unit that limits the increase or decrease of the fuel injection amount according to the torque estimated or detected by the torque detection unit to a predetermined amount, and a time limit set based on the natural frequency of the drive system of the vehicle. A torque control device for an internal combustion engine, comprising: injection amount correction means for releasing the restriction after a lapse of time.