JPH11117989A - Torque fluctuation control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately calculate a torque fluctuation reduction amount necessary to the high grade component of a torque fluctuation. SOLUTION: In an engine having an excitation device 31 to regulate excitation torque exerted on a crank shaft, excitation torque generated by the excitation device 31 is detected by a detecting means 32, the vibration acceleration of an engine power train is detected by a detecting means 33. From the detecting values, a transmission function of excitation torque, generated by the excitation device 31, and vibration acceleration of the engine power train is calculated by a calculating means 34. Based on this transmission function, excitation torque of the excitation device 31 is controlled so that the generation of vibration of an engine roll is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for actively reducing engine torque fluctuations caused by combustion excitation or inertia.

[0002]

2. Description of the Related Art It is possible to reduce a torque fluctuation of a crankshaft by generating a load of an alternator or a motor generator in a phase opposite to a torque generated by an engine. In this case, since the torque fluctuation can be expressed by multiplying the inertia of the rotating system by the rotational angular acceleration of the crankshaft, the rotational angular velocity of the crankshaft is detected, and this value is differentiated to obtain the rotational angular acceleration. A torque fluctuation is calculated in proportion to this value, and a torque load having an opposite phase is generated in consideration of the phase of the torque fluctuation (Transactions of the Japan Society of Mechanical Engineers, 1993, Vol. 59, No. 560). (See “Paper No. 92-1175”, “Reduction of Idling Vibration of Vehicle by Active Torque Control of Electric Auxiliary Equipment”).

[0003]

However, if the rotational angular velocity of the crankshaft is detected to detect a torque fluctuation and the rotational angular acceleration is calculated by differentiating this value, as in the conventional apparatus, the rotational angular acceleration is determined. Detection accuracy is low.
In order to detect the rotational angular velocity, a predetermined number of pulses are generated according to the rotation of the crankshaft (or the shaft that rotates in synchronization with the crankshaft). However, the number of detected pulses per one rotation of the crankshaft is small. Therefore, the detection accuracy of the higher-order component of the fluctuation torque is further reduced (if the number of pulses is increased, it is necessary to improve the sampling frequency and the cost increases).

Further, although the engine state changes between when the gear position of the automatic transmission is in the N range and when the gear position is in the D range, detecting the fluctuation of the rotation of the crankshaft irrespective of the gear position causes roll vibration. The control accuracy for reducing the transmission becomes insufficient (it is also necessary to consider the rotation fluctuation on the transmission side).

Accordingly, the present invention calculates the transfer function between the roll vibration acceleration and the torque input from the vibrating device under predetermined operating conditions. It is an object of the present invention to accurately calculate a required amount of torque fluctuation reduction up to a higher-order component of torque fluctuation by performing control so as to reduce vibration.

[0006]

According to a first aspect of the present invention, as shown in FIG. 6, in an engine having a vibration device 31 capable of adjusting a vibration torque applied to a crankshaft, the vibration device 31 generates the vibration. Means 32 for detecting the excitation torque and means 33 for detecting the vibration acceleration of the engine-power train
Means 34 for calculating a transfer function between the vibration torque generated by the vibration device 31 and the vibration acceleration of the engine-power train from the detected values, and reducing the engine roll vibration based on the transfer function. The vibration device 31
And means 35 for controlling the excitation torque of the motor.

In a second aspect of the present invention, in the first aspect, the transfer function is calculated from a change in engine roll vibration when a known impulse input is given by the vibrator when the engine is started.

In a third aspect of the present invention, in the first aspect, when a known input is given by the vibrating device in an initial state of the operating condition in which the roll vibration is a problem and which is first experienced after starting the engine. The transfer function is calculated from a change in engine roll vibration.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the vibrating device is a motor generator.

According to a fifth aspect of the present invention, in the fourth aspect, the motor generator is also used as a starter so as to mesh with a ring gear of a flywheel, and is rigidly connected to an engine side wall to reduce the exciting force of the motor generator. It is provided so that the reaction acts on the engine block.

[0011]

According to the first aspect of the present invention, the vibration torque required for reducing the vibration of the engine-power train is obtained by multiplying the reciprocal of the transfer function by the vibration acceleration of the engine-power train. Differential operation is not required as compared with the conventional device, and the required amount of torque fluctuation reduction up to a higher-order component of torque fluctuation can be accurately calculated. As a result,
Idle vibration and lock-up muffled sound can be significantly reduced.

When the engine is started, it is the timing at which disturbance occurs. Therefore, according to the second aspect of the present invention, it is possible to grasp the transmission characteristics without perceiving a sense of discomfort even if a vibrating force is applied by the vibrating device at the time of starting the engine. Becomes

According to the third invention, the transfer function changes due to the variation of the control object (that is, the difference in play (individual difference, change over time, etc.) even under the same operating conditions) and the load even with the same individual and the same rotational speed. ) And can be finely controlled. In other words, the roll vibration can be canceled directly in any use situation. Also,
When the transfer function is calculated even when the roll vibration becomes a problematic operating condition after the second engine start, the discomfort of the vibration due to the excitation force is sensed each time. The invention does not.

The belt expands and contracts when transmitting torque. In this case, the resonance point exists between, for example, 20 Hz and 30 Hz (the rotational speed of the engine is about 1200 rpm) when the accessory and the pulley are used as the inertia and the belt is used as the spring in the expansion and contraction direction. It will not be transmitted. Therefore, if the torque generated by the motor generator is continuously controlled in accordance with the combustion timing of the engine, the phases will not match.
Instead, the torque fluctuation may be increased. On the other hand, in the fifth invention, accurate transmission characteristics can be grasped and torque fluctuation reduction control can be performed without being affected by such drive system resonance caused by the belt (or chain) drive system.

[0015]

FIG. 1 is a perspective view of a power plant 1 (engine-power train). In the figure, 3
Is a cylinder block, 4 is an aluminum oil pan, 5 is an oil sump made of sheet metal, 6 is a cylinder head integrally connected to the cylinder block 3 with bolts, 7 is a rocker cover that covers the cylinder head 6, and an engine A transmission 8 as a power train is connected to the engine 2 via a torque converter (not shown). The power plant 1 including an engine and a power train is fixed to a vehicle body 10 via an engine mount 9 as shown in FIG.

Originally, the engine converts the reciprocating motion of the piston due to the combustion excitation force from the link mechanism using the connecting rod and the crankshaft into the rotational output. However, if the combustion excitation force fluctuates greatly, the crank-connecting rod mechanism is used. Fluctuations occur due to the swing of the motor. This torque fluctuation is transmitted to the transmission via a flywheel and a clutch (or a torque converter). On the other hand, these torque fluctuations acting on the crankshaft are also applied as a reaction force to the engine block as an exciting force. As a result, the engine vibrates in a roll, and the engine is displaced and excited on the engine mount to transmit the exciting force to the vehicle body. These phenomena increase the floor vibration of the steering wheel or the vehicle body as idle vibration during idling, and cause a problem such as a lock-up muffled sound during steady lock-up traveling.

In this case, the load of the alternator or the motor generator is generated in a phase opposite to the torque generated by the engine (accurately, in the case of the alternator, the absorption torque is increased or decreased).
Since it is possible to reduce the torque fluctuation of the crankshaft, the rotational angular acceleration is obtained by differentiating the rotational angular velocity of the crankshaft, and the torque fluctuation is calculated in proportion to this (the torque fluctuation is determined by the inertia of the rotating system. Is multiplied by the rotational angular acceleration), and a method has been proposed in which a torque load of the opposite phase is generated in consideration of the phase of the torque fluctuation. When the rotational angular acceleration is obtained, the detection accuracy of the rotational angular acceleration is low, and the engine state changes between when the transmission gear position is in the N range and when it is in the D range. The control accuracy for reducing the roll vibration is not sufficient only by detecting the rotation fluctuation of the shaft.

In order to cope with this, in the present invention, the transfer function between the roll vibration acceleration of the engine (the vibration acceleration of the engine-power train) and the torque input from the vibrating device is calculated during the operation, and the transfer function is obtained during the operation. Control to reduce roll vibration based on the transfer function.

For this reason, an acceleration pickup 11 for detecting roll direction vibration is mounted on a part of the cylinder block 3. The mounting position of the pickup 11 is determined by the inertia main shaft 25 of the power plant 1 (see FIG. 3).
It is desirable to orient the acceleration pickup 11 so that the main axis of the acceleration pickup 11 is as far away from the main body as possible and in the tangential direction of the roll vibration.

On the side wall of the cylinder block 3, a motor generator 12 which functions as a vibration device and also serves as a starter is fixed via a pedestal 13. When acting as a vibration device, it is driven according to the output from the inverter 14 (see FIG. 3), and the torque generated by the motor generator 12 acts on the entire power plant 1 as vibration torque.

By generating the excitation torque from motor generator 12 in a phase opposite to the torque generated by the engine, it is possible to reduce torque fluctuations of the crankshaft. More specifically, in FIG. 2, which is a principle diagram for reducing the torque fluctuation, a piston side force acts on the liner by the combustion excitation force of the engine, but the reaction force of the piston side force is applied to the crankshaft. The force F1 shown to the right from the center of the crankshaft is a force for rotating the engine 2 counterclockwise by the force F1 and the combustion excitation force. In contrast, the motor generator 12
A force F2 going diagonally upward and rightward and a force F3 going left and lower from the center of the crankshaft are reaction forces due to meshing of gears, and r1 +
A couple that rotates the engine 1 clockwise with the arm corresponding to the distance r2. This couple cancels the counterclockwise force accompanying the combustion excitation force.

In FIG. 2, when the inertia of the main flywheel is I1 (about 0.1 kgm ^{2 for a} 2-liter class gasoline engine) and the inertia of the motor generator as a sub-wheel is I2, I2 is ideal. In general, the reciprocal of the gear ratio (r1 / r2) is I
It is desirable that the value be multiplied by one. Therefore, when the inertia of the motor generator cannot be increased to this value due to the space, the effect of reducing the roll vibration is reduced accordingly.

FIG. 3 is a diagram in which an electric circuit is added to the mechanical configuration shown in FIG.

The output of the acceleration pickup 11 is desirably of a voltage type whose output is stable.
Input. In order to cut unnecessary high-frequency components from the output signal from the amplifier 21 (acceleration output is generally larger in a higher frequency region, so that the S / N ratio is reduced when overloading is considered), the low-pass filter 22 is used.
Is input to the arithmetic unit 23 via the.

An arithmetic unit 2 to which signals such as engine speed, boost pressure, and transmission gear position are input.
In 3, the motor generator 12 is operated as a vibrator under predetermined operating conditions, and a transfer function H between the roll vibration acceleration at this time and the torque input from the motor generator 12 is obtained.
Then, when the operating condition is such that the roll vibration of the engine becomes a problem, a control torque to be applied to the motor generator 12 as the vibrating device is calculated based on the transfer function H, and the roll torque is reduced by the control torque. To control.

The method of calculating the transfer function executed by the arithmetic unit 23 mainly composed of a microcomputer will be described in detail with reference to the flowchart of FIG.

Here, since the operating condition that requires a transfer function is an operating condition in which roll vibration is a problem, the transfer function is calculated when the operating condition in which roll vibration becomes a problem for the first time after the engine is started is calculated and stored. Let it be.

Roll vibration is a problem due to idle vibration of a vehicle (floor or steering) when the engine is idle or a lock-up muffled sound generated when the automatic transmission is locked up. Therefore, the operating condition in which roll vibration is a problem is a region of relatively low rotation and low load (for example, 2000 rpm or less and 1/2 load or less). In the following, for simplicity, the above case will be described.

In step 1, the ignition key switch is checked, and when it is ON, the gear position is checked in step 2 to determine whether the switch is in the N range or the D range.

In step 3, the engine speed and boost pressure (load) are read, and in step 4, it is checked whether or not these are in the above-mentioned operation range (relatively low rotation and low load range).

If it is in the above-mentioned operating range, the process proceeds to step 5, and it is determined whether or not the transfer function has already been calculated in the operating range after starting. If the transfer function has not been calculated in the operation range, the process proceeds to step 6.

In step 6, a drive current to the motor generator 12 is instructed in order to make the motor generator work as a vibration device. At this time, a driving torque (DC torque required for starting when a transfer function is obtained at the time of starting) is generated in the motor generator 12 in consideration of a gear ratio (a gear ratio between the motor generator 12 and the flywheel 15 (see FIG. 3)). At the same time, a signal in which a fluctuation component uncorrelated with the combustion excitation force is also superimposed is given.

Here, the reason why the overlapped signal is also given to the fluctuation component unrelated to the combustion excitation force is as follows. The measured vibration acceleration includes vibration generated by combustion of the engine. In order to separate this, uncorrelated signals are superimposed. Also,
The transmission characteristics for the combustion excitation force from the combustion excitation force on the engine side also become clear.

In step 7, the roll vibration acceleration at this time is measured, and in step 8, the transfer function H is calculated by dividing the roll vibration acceleration by the drive torque generated by the motor generator 12.

Since the driving torque generated in the motor generator 12 is directly proportional to the current or voltage of the motor, the driving torque is estimated using the current or voltage applied to the inverter 14.

In step 9, the latest value is stored in the memory according to the gear position at that time.

Here, instead of obtaining one transfer function for the entire operation range (region with relatively low rotation and low load), this operation region is further divided into a plurality of small regions. The transfer function (transfer function for each frequency) is stored for each small area. That is, a map of the transfer function having the rotation speed and the load as parameters is provided for each gear position (one map for each of the N range and the D range), and a different value is provided for each small area on each map. Will be stored.

The flowchart in FIG. 5 is for performing torque control based on the transfer function obtained when the roll vibration becomes a problematic operating condition after the transfer function is obtained in this manner.

In step 11, the engine speed and boost pressure are read, and in step 12, it is determined whether or not these are within a predetermined operating range. This predetermined operating range is an operating range in which the roll vibration described above becomes a problem. If it is not in the predetermined operation range, the roll vibration does not cause a problem, and thus the current process is terminated.

If it is within the predetermined operating range, step 13
After checking whether the gear position is in the N range or the D range, the roll vibration acceleration A at that time detected by the acceleration pickup 11 in steps 14 and 15 is measured, and the vehicle sensitivity and the mount insulator ( The difference between the target acceleration of the engine mount vibration determined from the spring constant) and the actual acceleration A is compared with zero.

As a result of the comparison, if the value of the target value -A is larger than 0, it is necessary to reduce the roll vibration. Therefore, the process proceeds to step 16 and thereafter, in which the motor generator 12 is operated as a vibration device to reduce the engine mount vibration. Excitation force is applied in the direction to suppress.

More specifically, a value obtained by multiplying the perturbation torque T by the transfer function H (t) corresponding to the gear position in step 16 is obtained as the acceleration level Ac when the motor is controlled, and the target value -A The value and this Ac are compared in step 17, and the operations in steps 16 and 17 are repeated until the value of target value-A matches this Ac.

The above-mentioned perturbation torque T is a torque that is perturbed with the necessary generated torque Tm0 (average numerical value) of the motor generator as an initial value, and Tm0 is obtained by searching a map. This map is also a map using the engine speed and the load as parameters, and is divided into a plurality of regions like the map of the transfer function.

When the value of the target value -A coincides with Ac, the process proceeds from step 17 to steps 18 and 19, in which the value of the perturbation torque T is transferred to the control torque Tm, and the control torque Tm (is obtained. Output current value) to the inverter.

To put it simply, the control torque Tm can be obtained by setting Tm = (target value−A) / h (t). When the inverse of the transfer function H (t) is obtained, If the transfer function H (t) is infinitely close to 0 (anti-resonance point), the error is enlarged. Therefore, the convergence calculation is performed in the form of multiplication to obtain Tm, thereby preventing a decrease in control accuracy. It is. Of course, it goes without saying that the control torque Tm may be obtained from Tm = (target value−A) / h (t).

In this way, the difference between the target roll vibration acceleration of the engine and the actual roll vibration acceleration A is canceled by applying the control torque Tm obtained based on the transfer function to the power plant 1 from the motor generator 12. be able to.

Next, the operation of the present invention will be described.

Normally, torque fluctuation is detected by detecting a rotational angular velocity, performing a differential operation on the rotational angular velocity to obtain a rotational angular acceleration, and multiplying the rotational angular acceleration by an inertia Ip of the engine to calculate a torque fluctuation. In general, the accuracy of the differential calculation may be low, and the number of detection pulses must be increased in order to calculate the higher-order component of the torque fluctuation. Is impossible, and control is performed in a state several cycles before.

On the other hand, in the present invention, which is a torque fluctuation reducing system using a transfer function, no differential operation occurs,
Torque T required to reduce engine mount vibration
Since m is obtained by multiplying the reciprocal of the transfer function by the engine mount vibration acceleration A (convolution integral in the time domain), the required torque fluctuation reduction amount up to the higher-order component of the torque fluctuation can be accurately calculated as compared with the conventional device. Can be calculated.

Also, by providing the motor generator with a predetermined inertia, the system for reducing the roll vibration can be made compact. When trying to cancel torque fluctuations using only an electric motor as in the past, a very large motor was required, and the layout and weight were not realistic. (Engines have large fluctuations compared to the average output. Is remarkable when the load is large.) If the motor generator has a predetermined inertia, there is a torque that can be physically canceled, so that it is sufficient to only cancel the remaining fluctuation components electrically, so a compact system can be achieved. It becomes.

In the embodiment, the case where the transfer function is actually calculated has been described. However, if the calculation load is to be kept low,
A function in which a transfer function for each frequency is stored in a map of an operating region for each gear position may be prepared in advance, and torque control may be performed according to this map.

In the embodiment, the description has been given of the case where the transfer function is calculated from the change in the engine roll vibration by giving a known input from the motor generator when the operating condition in which the roll vibration is a problem is experienced for the first time after starting the engine. The transfer function may be calculated from a change in engine roll vibration when a known impulse input is given by the generator when the engine is started.

When obtaining the transfer function, the frequency characteristic of the input excitation force and the frequency characteristic of the engine mount vibration as the response are divided. Therefore, measurement of the excitation force and the acceleration level and frequency analysis are required. In the present embodiment, since this exciting force is a torque input by the motor generator, this measurement is necessary. In this case, measuring the torque using a torque sensor is also an example, but the cost is increased, so the relationship between the current flowing through the motor generator and the torque is determined in advance, and the current is measured to convert the torque. I do. At this time, the expression “impulse” is used to mean that torque is generated for a limited time. If the generated torque is predicted based on the motor drive current, it is not necessary to measure the actual current. When the engine is started, it is the timing at which disturbance occurs, so that even if an exciting force is applied by the motor generator at the time of starting the engine, it is possible to grasp the transfer characteristics without sensing the unnaturalness of the vibration.

However, the transfer function obtained at the start of the engine with the gear position in the N range has an optimum value when the gear position is in the N range.
If it is used at the time of lock-up when the gear position is in the D range, a shift occurs. Therefore, it is desirable that the transfer function used at the time of lock-up is a transfer function obtained when the gear position is in the D range.

In the embodiment, when calculating the transfer function,
Although the gear position is considered in addition to the operating range, the accuracy of torque control can be further improved by considering the driving state of the auxiliary equipment.

[Brief description of the drawings]

FIG. 1 is a perspective view of a power plant 1 according to a first embodiment.

FIG. 2 is a principle diagram for reducing torque fluctuation.

FIG. 3 is a control system diagram of the first embodiment.

FIG. 4 is a flowchart for explaining calculation of a transfer function.

FIG. 5 is a flowchart illustrating torque control based on a transfer function.

FIG. 6 is a diagram corresponding to claims of the first invention.

[Explanation of symbols]

 Reference Signs List 1 power plant 2 engine 8 transmission (power train) 12 motor generator 14 inverter 21 acceleration pickup 23 arithmetic unit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yasuyuki Asahara Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa

Claims (5)

[Claims] 1. An engine having a vibration device capable of adjusting a vibration torque applied to a crankshaft, means for detecting a vibration torque generated by the vibration device, and detecting a vibration acceleration of an engine-power train. Means for calculating a transfer function between the vibration torque generated by the vibration device and the vibration acceleration of the engine-power train from the detected values; and a means for reducing engine roll vibration based on the transfer function. Means for controlling a vibration torque of the vibration device. 2. The torque fluctuation control device according to claim 1, wherein the transfer function is calculated from a change in engine roll vibration when a known impulse input is given at the time of engine start by the vibration device. 3. The transfer function based on a change in engine roll vibration when a known input is given by the vibrator in an initial state of operating conditions that roll vibration is a problem and an operating condition first experienced after starting the engine. The torque fluctuation control device according to claim 1, wherein the torque fluctuation control device calculates: 4. The torque fluctuation control device according to claim 1, wherein said vibration device is a motor generator. 5. The motor generator is also used as a starter so that it engages with a ring gear of a flywheel, and is rigidly connected to an engine side wall so that a reaction of the excitation force of the motor generator acts on an engine block. The torque fluctuation control device according to claim 4, wherein the torque fluctuation control device is provided.