JP6217612B2 - Vehicle vibration control device - Google Patents

Description

  The present invention relates to a control device that reduces vibration of a vehicle, and more particularly to a device that controls torque of a driving force source so as to reduce vibration during traveling of a hybrid vehicle.

  When the vehicle travels, vibration inevitably occurs. Patent Document 1 describes an apparatus configured to reduce vibration caused by an engine in a hybrid vehicle (HV vehicle) including the engine. The apparatus described in Patent Document 1 is configured such that a motor is connected to an output shaft of an engine via a clutch, and torque output from the engine and the motor is transmitted to drive wheels via a transmission. The hybrid vehicle is configured to prevent abnormal vibration, and the clutch is provided with a damper having a rigid inflection point. At the resonance point of the drive system, each torque is changed so as not to change the total drive torque obtained by adding the engine torque and the motor torque, and the inflection point of the damper is avoided. .

JP 2014-088159 A

  When the hybrid vehicle is running, vibrations may occur due to the rotational unbalance of the tires acting as a force. The device described in Patent Document 1 is a device configured to reduce or prevent vibrations in which torque fluctuations of the engine are a forced force, so that the hybrid vehicle stops the engine and runs with the driving force of the motor. In this state, it is impossible to estimate the resonance of the hybrid vehicle and to suppress or prevent the resonance. Moreover, even if the apparatus described in Patent Document 1 can avoid the rigidity inflection point of the damper, the frequency of resonance caused by the rotational imbalance of the tire cannot be known in advance. In the invention, it is difficult to suppress or prevent such resonance at an unspecified frequency.

  The present invention has been made paying attention to the above technical problem, and provides a vehicle vibration control device capable of suppressing or preventing resonance or excessive vibration when the hybrid vehicle is running on a motor. It is intended to do.

  In order to achieve the above object, the present invention provides a power split mechanism that splits power output from an engine into a first motor side having a power generation function and a drive wheel side, and rotation of the output shaft of the engine in a predetermined direction. A brake mechanism that stops the engine, a damper that is provided between the brake mechanism and the power split mechanism and has a spring constant that changes depending on a twist angle, and a second motor that has a power generation function that adjusts torque transmitted to the drive wheels A vibration control apparatus for a vehicle capable of running with the power of the first motor and the second motor in a state where the rotation of the output shaft in the predetermined direction is stopped by the brake mechanism. The spring constant of the damper is estimated based on the output torque of the first motor in a state where the motor is running with the power of at least the second motor of the two motors. It is determined whether or not the vehicle speed causes a vibration that enters a resonance band that is a predetermined frequency range including a resonance point in a state of traveling at a spring constant, and is determined to be a vehicle speed that causes a vibration that enters the resonance band. In this case, the spring constant is changed by changing the torque of the first motor applied to the damper.

  In the present invention, when it is determined that vibration that enters the resonance band occurs, the spring constant of the damper is changed. Since the resonance band is a frequency range corresponding to the spring constant of the damper, the resonance band changes when the spring constant is changed. As a result, it is possible to suppress or prevent the occurrence of excessive vibration even when traveling at the vehicle speed at that time.

It is a flowchart for demonstrating an example of the control performed with the vibration control apparatus which is an example of this invention. It is a diagram which shows the relationship between a spring constant and a resonance point or a resonance band, and a relationship between a tire rotation primary frequency and a vehicle speed. It is a diagram showing typically an example of change of torque of the 1st motor for change of a spring constant, and change of torque of the 2nd motor for compensating drive torque. It is a schematic diagram which shows the drive system of the hybrid vehicle which can be made into object by this invention. It is a torsional characteristic diagram showing the relationship between the torque of the first motor, the twist angle and the spring constant. It is a diagram which shows the relationship between a tire rotational frequency, a surge level, and a spring constant.

  The present invention is an apparatus for controlling vibration of a hybrid vehicle that uses an engine and a motor having a power generation function as a power source and can select EV traveling that travels only by the power of the motor. An example of the drive system of the hybrid vehicle will be briefly described. FIG. 4 schematically shows a so-called two-motor type hybrid vehicle. A power split mechanism 4 is provided that splits the power output from the engine 1 into a first motor (MG1) 2 side and a drive wheel 3 side. The power split mechanism 4 is basically constituted by a differential mechanism including three rotating elements, more specifically, a planetary gear mechanism, for example, a first motor is connected to a sun gear, and an engine 1 is connected to a carrier. Can be configured to output torque from the ring gear toward the drive wheel 3.

  A brake mechanism 6 that stops the rotation of the output shaft (crankshaft) 5 of the engine 1 is provided to enable EV traveling and reduce power loss due to dragging the engine 1 during EV traveling. When the power split mechanism 4 is configured by a differential mechanism such as a planetary gear mechanism, when the first motor 2 outputs a torque for traveling, the output shaft 5 of the engine 1 has a negative rotation direction (original of the engine 1). Torque in the direction opposite to the rotation direction) is applied. The torque is received by the brake mechanism 6 so as to stop the rotation of the output shaft 5 in the negative direction. Therefore, the brake mechanism 6 may be configured to stop rotation in both forward and reverse directions, such as a friction brake and a dog clutch, or may be a one-way clutch.

  A damper 7 is provided between the brake mechanism 6 and the power split mechanism 4 to suppress engine torque vibration. The damper 7 is a spring damper as described in, for example, Patent Document 1 described above, and a coil spring is disposed between a driving side plate and a driven side plate. When the plate is relatively twisted, the coil spring is compressed to reduce vibration. In addition, a plurality of types of coil springs having different lengths and spring constants are provided as the coil springs. Therefore, the damper 7 is configured such that the relationship between the torsion angle and the torque, that is, the torsion characteristics, is not constant. An example thereof is shown in FIG. 5, and the example shown here is an example in which the spring constant changes in three stages (K1 <K2 <K3). In the specific example described here, as described above, since the torque for traveling output from the first motor 2 is applied to the output shaft 5 or the brake mechanism 6, the torque output from the first motor 2. Acts on the damper 7 as a torque that increases or decreases a torsion angle. Therefore, the twist angle of the damper 7 can be changed by changing the twist angle of the damper 7 by the torque of the first motor 2. FIG. 5 also shows the direction of change in the twist angle due to the torque of the first motor 2. In FIG. 5, the negative region of the torque (MG1 torque) of the first motor 2 is a region of torque output by the first motor 2 rotating in the negative rotation direction, and the positive region is the first region. This is a region of torque output by the motor 2 rotating in the forward rotation direction.

  When the rotation of the output shaft 5 of the engine 1 is stopped by the brake mechanism 6, vibration from the drive wheel (tire) 3 side is input to the damper 7. The vibration is caused by rotational imbalance of the drive wheels 3 and road surface unevenness. Since the torsional characteristics of the damper 7 change as described above, the resonance point of the damper 7 or the entire drive system changes according to the spring constant of the damper 7. FIG. 6 shows the frequency of vibration input from the drive wheel 3 side in terms of tire rotation frequency, and the tire rotation frequency and the predetermined torque from the drive wheel 3 side when the spring constant is varied in various ways. It is the figure which showed the relationship with the surge level (vibration acceleration) at the time of input. The spring constant can be replaced with a torque per unit angle of the twist angle. As shown in FIG. 6, in the drive system using the above-described damper 7, the resonance point changes to the high frequency side as the spring constant of the damper 7 increases.

  The hybrid vehicle shown in FIG. 4 further includes a second motor 8. The second motor 8 is a motor having a power generation function similarly to the first motor 2 described above, and is connected to a predetermined portion of a path for transmitting torque from the power split mechanism 4 to the drive wheels 3. That is, the second motor 8 is configured to increase or decrease the torque transmitted to the drive wheel 3. The first motor 2 and the second motor 8 described above are connected to a power storage device such as a battery via an inverter (not shown). These motors 2 and 8 are configured so as to be able to exchange electric power with each other. The electric power generated by the first motor 2 is supplied to the second motor 8 so that the second motor 8 functions as a motor. The power generated by the second motor 8 is supplied to the first motor 2 so that the first motor 2 functions as a motor. In addition, the motors 2 and 8 are supplied with electric power from the power storage device so that they function as motors and travel by EV. In addition, the code | symbol 9 in FIG. 4 shows the differential gear used as a final reduction gear.

  An electronic control unit (ECU) 10 is provided for electrically controlling the operation state such as the engagement and release of the brake mechanism 6 and the torques of the motors 2 and 8 described above. The ECU 10 is mainly composed of a microcomputer, and uses input data or prestored data to perform calculations according to a program stored in advance, and uses the result of the calculation as a control command signal for the brake mechanism 6. And the motors 2 and 8 or the inverter. The input signal includes the state of execution or non-execution of EV traveling, the output torque of the first motor 2, the accelerator opening or throttle opening, the operation amount of the accelerator pedal or the brake pedal, the vehicle speed, the rotational speed of the driving wheel 3, and the like. is there.

  In the EV traveling state, since the engine 1 is stopped, the damper 7 operates to absorb vibration (torque fluctuation) transmitted from the drive wheel 3 side. Therefore, the resonance point is determined according to the spring constant (torsional characteristic). The vibration control apparatus as an example of the present invention controls the spring constant (torsional characteristic) of the damper 7 so as to reduce such vibration during EV traveling or suppress excessive vibration due to resonance or the like. It is configured. Specifically, the control is performed by the ECU 10 described above. An example of the control is shown in the flowchart of FIG. The routine shown in FIG. 1 is repeatedly executed when the hybrid vehicle is traveling, and it is first determined whether or not EV traveling is in progress (step S1). The EV traveling is a state in which the two motors 2 and 8 output power for traveling, or the second motor 8 outputs power for traveling. Judgment can be made based on the control state. Further, since EV travel is set according to the vehicle speed, the accelerator opening, and the like, the determination in step S1 can be made based on the vehicle speed and the accelerator opening. In step S1, the rotation of the output shaft 5 may be replaced with a determination as to whether or not the brake mechanism 6 can stop the rotation, or these two determinations may be performed simultaneously.

  If a negative determination is made in step S1, the process returns without performing any particular control. On the other hand, if a positive determination is made in step S1, the spring constant set at that time and the vehicle speed at which resonance occurs are obtained (step S2). Since the vehicle is traveling in the EV mode, the vibration is caused by the fluctuation of the torque transmitted from the drive wheel 3 side. In that case, since the damper 7 is twisted by the torque of the first motor 2, the twist angle of the damper 7 and the spring constant associated therewith are based on the torque of the first motor 2 due to the relationship shown in FIGS. 5 and 6 described above. Can be estimated or obtained. The resonance point at the estimated or calculated spring constant can be obtained based on the relationship shown in FIG. On the other hand, the relationship between the rotation primary frequency and the vehicle speed accompanying the rotation of the drive wheels 3 can be obtained in advance based on the outer diameter of the drive wheels 3 being used. An example is shown in FIG. In FIG. 2, the same diagram as FIG. 6 described above is also shown. Therefore, when a resonance point based on the spring constant is obtained, the vehicle speed at which resonance occurs or a surge level (that is, vibration) is within a predetermined frequency range including a resonance point that exceeds a predetermined tolerance in design (becomes NG). The vehicle speed of the resonance band can be obtained based on FIG.

  The lower limit vehicle speed A and the upper limit vehicle speed B of the resonance band thus determined are determined, and it is determined whether or not the current vehicle speed V is in the vehicle speed range (whether A <V <B). Step S3). This determination corresponds to a determination as to whether resonance occurs at the current vehicle speed or whether the vibration exceeds an allowable range. If a negative determination is made in step S3, there is no need to newly perform control for vibration reduction, and the routine returns.

  On the other hand, when a positive determination is made in step S3, it is determined whether or not the vehicle speed changes rapidly. Specifically, it is determined whether the throttle opening is not fully open (whether it is not WOT), whether the change in accelerator opening is gradual, whether the brake operation amount is changed, or whether the operation speed is gradual. (Step S4). These determinations may be made by predetermining a threshold value through experiments, simulations, or the like, and comparing the detected operation amount with the threshold value. If a negative change is determined in step S4 because the change in the vehicle speed is more than assumed in the design, the actual vehicle speed quickly passes the vehicle speed in the resonance band, and control for vibration reduction is performed. Therefore, it is considered that there is no need to perform a new operation.

  If the determination in step S4 is affirmative, when the torque of the first motor 2 is controlled in order to change the spring constant of the damper 7, the fluctuation of the drive torque associated with the torque control is suppressed. It is determined whether or not the torque of the second motor 8 can be changed (step S5). When the power split mechanism 4 described above is constituted by a planetary gear mechanism, if the torque of the first motor 2 is increased in the negative rotation direction so as to increase the spring constant of the damper 7 in the positive rotation direction, the output of the engine 1 is increased. Since the shaft 5 is fixed by the brake mechanism 6, the torque output from the power split mechanism 4 increases. On the other hand, when the torque of the first motor 2 is increased in the positive rotation direction so as to increase the spring constant of the damper 7 in the negative rotation direction, the torque output from the power split mechanism 4 decreases. In order to suppress such fluctuations in driving torque, the torque of the second motor 8 is increased or decreased. In that case, electric power is output from the power storage device, the output amount is decreased, or charging is performed. On the other hand, depending on the remaining charge (SOC) of the power storage device, discharging or charging is restricted, and accordingly, torque control of the second motor 8 is restricted. In step S5, it is determined whether or not the control for the second motor 8 is restricted. Therefore, if there is no remaining power to perform torque control of the second motor 8 and a negative determination is made in step S5, the process returns without performing any particular control.

  On the other hand, if the torque control of the second motor 8 is possible and a positive determination is made in step S5, the spring constant of the damper 7 is changed, and accordingly the resonance point or resonance band is set to the high frequency side or low. Change to the frequency side (step S6). For example, if EV driving is performed in a so-called double drive mode in which the first motor 2 outputs torque in the negative rotation direction and the second motor 8 outputs torque in the positive rotation direction, and the vehicle speed is high to some extent, Since the output torque of one motor 2 is large, the resonance point is on the high vehicle speed side. If the resonance point is reduced so that the actual vehicle speed does not enter the vehicle speed in the resonance band in this state, the output torque (torque in the negative rotation direction) of the first motor 2 is reduced. This state is shown in FIG. As described above, when the torque of the first motor 2 is changed so as to increase in the positive rotation direction (so as to reduce the torque in the negative rotation direction), it is output from the power split mechanism 4 toward the drive wheels 3. Torque decreases. The output torque of the second motor 8 is increased so as to compensate for such a decrease in torque. The control amount can be obtained based on the current value of the first motor 2, the gear ratio in the power split mechanism 4, and the like.

  The torque of the first motor 2 for changing the resonance point may be reduced, and in this case, a torque reduction gradient (torque rate) is set according to the torque of the first motor 2 (step S7). Specifically, when the absolute value of the torque of the first motor 2 is reduced to a predetermined small torque of about “0”, the torque rate is set to a predetermined small value, on the contrary, When the torque of one motor 2 is not reduced to the predetermined small torque, torque rate reduction control is not executed. This control of the torque rate is to prevent so-called rattling noise. That is, by reducing the torque of the first motor 2, the force to pinch the coil spring in the damper 7 becomes small, and when the excitation force that changes positively and negatively becomes larger than the pinching force, the twist is suddenly released. May cause a rattling sound. In order to avoid or suppress such a situation, the torque rate is moderated.

  Although specific examples of the present invention have been described above, the present invention is not limited to the specific examples described above, and the present invention adopts various configurations that do not deviate from the configurations described in the claims. Good.

  DESCRIPTION OF SYMBOLS 1 ... Engine (ENG), 2 ... 1st motor (MG1), 3 ... Drive wheel, 4 ... Power split mechanism, 5 ... Output shaft (crankshaft), 6 ... Brake mechanism, 7 ... Damper, 8 ... 2nd motor 9 ... Final reduction gear, 10 ... Electronic control unit (ECU).

Claims (1)

A power split mechanism that splits the power output by the engine into a first motor side having a power generation function and a drive wheel side; a brake mechanism that stops rotation of the output shaft of the engine in a predetermined direction; the brake mechanism and the power split And a second motor having a power generation function that adjusts the torque transmitted to the drive wheel, and that rotates the output shaft in the predetermined direction. In a vehicle vibration control device capable of traveling with the power of at least the second motor of the first motor and the second motor while stopped by the brake mechanism,
Estimating the spring constant of the damper based on the output torque of the first motor in a state of running with the power of the first motor and the second motor;
Determining whether the vehicle speed causes a vibration to enter a resonance band that is a predetermined frequency range including a resonance point in a state of traveling with the estimated spring constant;
The vehicle is configured to change the spring constant by changing the torque of the first motor applied to the damper when it is determined that the vehicle speed causes vibrations entering the resonance band. Vibration control device.

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