JP2007321742A - Vibration suppression device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress back-and-forth vibration occurring at acceleration of a vehicle from an initial period in which the vibration starts without losing an accelerating feeling and to reduce shock and a swaying feeling due to vibration. <P>SOLUTION: When an accelerator pedal is stepped on and vibration control at acceleration is performed, the ignition timing is delayed by a torque down correction value, and an engine torque rising stepwisely is made to torque down and applied as a reversal phase torque with respect to the vibration before a first peak of an amplitude waveform of back-and-forth vibration appears. Thereby, the peak of the first amplitude of the back-and-forth vibration is suppressed and shock is reduced. Also, the swaying feeling occurring in a damping process of the vibration is reduced and a driver is not given an uncomfortable feeling. Further, as the reversal phase torque is applied before the first peak of the amplitude waveform of the back-and-forth vibration appears, the acceleration feeling is not lost due to starting of vehicle acceleration corresponding to the accelerator operation being slowed, contributing to improvement in driving performance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle vibration suppression device that suppresses vibration generated in a drive system of a vehicle with engine torque having a phase opposite to that of the vibration.

  In vehicles such as automobiles, vibrations are generated due to engine rotation fluctuations, which not only causes discomfort to the occupant, but also may lead to deterioration in driving feeling. As a technology for suppressing this vibration, a technology for suppressing the vibration by smoothing the rising of the engine torque is known, but there is a problem that the acceleration feeling is impaired if the vibration is sufficiently suppressed. .

For this reason, for example, as disclosed in Patent Document 1, a technique is often employed in which torque having a phase opposite to that of vibration is applied to attenuate the vibration. The technology disclosed in Patent Document 1 suppresses fluctuations in engine rotation speed by the generated torque of the generator motor, and calculates the torque to be generated by the generator motor by detecting and feeding back the engine rotation speed. ing.
JP-A-5-302526

  However, in the technique of generating torque that suppresses vibration after detecting engine rotation fluctuation, as in the technique disclosed in Patent Document 1, reverse-phase torque is generated after vibration occurs. For this reason, it is possible to use a system that produces a relatively large shock at first, such as the longitudinal vibration of the vehicle that occurs with the accelerator operation during acceleration, and then the vibration with a sense of vibration is attenuated. Although it is possible to suppress the feeling, it is difficult to suppress the initial shock.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and can suppress the longitudinal vibration that occurs during acceleration of the vehicle from the beginning when the vibration starts without impairing the acceleration feeling, and can reduce the vibration shock and feeling of vibration. An object of the present invention is to provide a vibration suppression device.

  In order to achieve the above object, a vehicle vibration suppression device according to the present invention is a vehicle vibration suppression device that suppresses vibration generated in a vehicle drive system with engine torque having a phase opposite to that of the vibration. Based on a model in which the twisting element is expressed by a spring system, the longitudinal vibration predicting means for predicting the longitudinal vibration generated during acceleration of the vehicle and the timing for giving the engine torque in the reverse phase are predicted by the longitudinal vibration predicting means. Based on the result, torque down timing setting means that is set at an initial stage where the longitudinal vibration starts, and engine torque is reduced by retarding the ignition timing of the engine at the timing set by the torque down timing setting means. Thus, the present invention is characterized by comprising reverse-phase torque generating means for generating the reverse-phase engine torque.

  The vehicle vibration suppression device according to the present invention can suppress the longitudinal vibration that occurs during acceleration of the vehicle from the beginning of the vibration without impairing the acceleration feeling, and can reduce the shock and feeling of vibration.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 relate to an embodiment of the present invention, FIG. 1 is a schematic configuration diagram showing a vehicle control system, FIG. 2 is an explanatory diagram showing a torsional resonance model of a drive system, and FIG. 3 is a torque down setting. FIG. 4 is a flowchart of the routine, FIG. 4 is a flowchart of an ignition timing setting routine, and FIG. 5 is an explanatory diagram showing the relationship between engine torque and vehicle longitudinal vibration.

  In FIG. 1, reference numeral 1 denotes a vehicle, and in this embodiment, a four-wheel drive vehicle. An engine 2 is mounted on the front portion of the vehicle 1, and a transmission 3 is connected to the output shaft of the engine 2. A center differential device 4 including a driving force distribution mechanism including a hydraulic multi-plate clutch and a planetary gear and a differential limiting mechanism is integrally connected to the rear portion of the transmission 3. The center differential device 4 attaches the propeller shaft 5 to the center differential device 4. It is connected to the rear differential device 6 via the front drive shaft 7 and to the front differential device 8 via the front drive shaft 7.

  The output of the engine 2 is shifted to a predetermined speed by the transmission 3 and then the driving force is distributed to the front wheel side and the rear wheel side via the center differential device 4. The driving force distributed to the rear wheel side is transmitted to the left and right rear wheels 9, 9 via the rear differential device 6, and the driving force distributed to the front wheel side is transmitted to the left and right front wheels 10, 10 via the front differential device 8. Is transmitted to.

  On the other hand, reference numeral 50 denotes an electronic control device mounted on the vehicle 1 and is configured around a microcomputer. In FIG. 1, an electronic control unit (ECU) for engine control is shown as a representative example, but the vehicle 1 is also equipped with a plurality of electronic control units including an electronic control unit for transmission control. ing.

  The engine control ECU 50 is connected to a crank angle sensor 15, an accelerator sensor 16, and various sensors and switches for detecting an operation state such as an intake air amount sensor and an air-fuel ratio sensor. The ECU 50 controls fuel injection through an injector (not shown), intake control through an electronically controlled throttle device (ETC) 20, spark plug 17 and igniter 18 based on signals from these sensors and switches. Various controls such as ignition timing control via the engine are executed.

  At the same time, in order to prevent vehicle longitudinal vibration at the time of acceleration, the ECU 50 performs vibration suppression control that suppresses vibration by applying an engine torque having a phase opposite to the engine rotation fluctuation. The vibration suppression control by the ECU 50 is a control that effectively suppresses vehicle longitudinal vibration during acceleration by applying a reverse-phase torque at an early stage when vibration starts, and the initial stage before the vibration during acceleration increases. The reverse phase torque is applied before the stage, that is, the vibration becomes substantially significant. As a result, it is possible to suppress the shock at the time of acceleration and the feeling of swaying, and to suppress the shock at the initial stage when the vibration starts without impairing the feeling of acceleration.

  The vehicle longitudinal vibration at the time of acceleration is caused by exciting a resonance mode of torsional vibration in the drive system by using a transient fluctuation of engine torque as an excitation force. That is, the engine torque at the time of acceleration due to depression of the accelerator pedal can be usually expressed as a step (or ramp) input. For this reason, during normal acceleration, the torsional resonance primary mode of the drive system is excited, resulting in damped free vibration.

  As shown in FIG. 2, the primary mode of the drive system torsional resonance includes an equivalent mass M1 of the flyhole and an equivalent mass M2 of the vehicle, and a torsion element such as a drive system clutch and a drive shaft as a spring system. It can be expressed by a simple model of harmonic motion (model replaced with a translational vibration system) that is expressed by an equivalent stiffness K and an equivalent damping coefficient C. In the harmonic motion, a component having a phase opposite to the speed works as a damping force. Therefore, as shown in the following equations (1) and (2), the vehicle is obtained from the transmission force F1 when the engine torque F is applied to the simple model. By obtaining the longitudinal acceleration A2, the vehicle longitudinal vibration with the engine torque transient fluctuation as the excitation force is predicted, and the engine torque of the reverse phase that is delayed by 90 ° with respect to the transmission force F1 in FIG. By giving in stages, the vehicle longitudinal vibration can be effectively suppressed.

A1 = {F−K × (X1−X2) −C × (V1−V2)} / M1 (1)
A2 = {K × (X1−X2) −C × (V1−V2)} / M2 (2)
However, A1, V1, and X1 are the acceleration, speed, and displacement on the equivalent mass M1 side, respectively, and A2, V2, and X2 are the acceleration, speed, and displacement on the equivalent mass M2 side, respectively.

  Specifically, when the ECU 50 increases the engine torque stepwise in response to accelerator depression during acceleration, at least the first peak in the vibration waveform of the vehicle longitudinal vibration is generated by the function as the reverse phase torque generating means. In the initial stage before occurrence, the ignition timing of the engine 2 is retarded by a short period to reduce the torque from the stepped base torque, thereby giving engine torque in a phase opposite to vibration.

  The torque-down timing (torque-down start timing and end timing) and the torque-down amount (ignition timing retard angle and retard amount) are set by the function of the ECU 50 as torque-down timing setting means. It is determined based on the amplitude and frequency of the vehicle longitudinal vibration predicted using the simple model formula by the function as the predicting means.

  Hereinafter, the vibration suppression control of the vehicle longitudinal vibration by the ECU 50 will be described with reference to the flowcharts of FIGS. The vibration suppression control includes the torque down setting routine of FIG. 3 that realizes the functions of the ECU 50 as the longitudinal vibration prediction means and the torque down timing setting means, and the ignition of FIG. 4 that realizes the functions of the ECU 50 as the reverse phase torque generation means. This is performed by a timing setting routine.

  In the torque down setting routine of FIG. 3, first, the signal of the accelerator sensor 16 is read in the first step S1, and the depression amount and depression speed of an accelerator pedal (not shown) are detected. Next, it progresses to step S2 and it is determined whether the acceleration condition which implements damping control is satisfied. For example, when the amount of depression of the accelerator pedal is greater than or equal to a predetermined threshold and the depression speed is greater than or equal to a predetermined threshold, it is determined that an acceleration condition for performing vibration suppression control is satisfied. The threshold value for executing the vibration suppression control may be set to a value that can be applied in general during acceleration including slow acceleration, but in general, there is no possibility of occurrence of vehicle longitudinal vibration that is particularly problematic during slow acceleration. Therefore, it is set to a value corresponding to sudden acceleration.

  Note that the acceleration condition of this vibration suppression control may be determined by comparing the change speed of the engine speed with a threshold value.

  In step S2, if the acceleration condition is not satisfied, the routine exits without executing the vibration suppression control. If the acceleration condition is satisfied, the process proceeds from step S2 to step S3, and the control content of the ETC 20 is read. The control content of the ECTC 20 is mainly target control to a throttle opening satisfying the driver's required torque corresponding to the accelerator pedal depression amount, and the accelerator opening (accelerator pedal depression amount) based on the signal from the accelerator sensor 16 The target throttle opening is set by referring to a table using the engine speed based on the signal from the crank angle sensor 15 as a parameter.

  Next, the process proceeds to step S4, and the amount of increase and speed of engine torque increased by acceleration are calculated as the engine torque fluctuation amount from the control content by the ETC 20, and in step S5, the accelerator pedal is depressed from the engine torque fluctuation amount. Predicts the magnitude (amplitude) and period of the vehicle longitudinal vibration generated by. This vehicle longitudinal vibration prediction is performed by simulating the acceleration of the torsional vibration of the drive system transmitted from the engine 2 via the transmission 3 by applying the specifications of the vehicle to be controlled in advance to the above-mentioned simple model, In addition, using an experiment with an actual machine, a map is made for each gear position of the transmission 3, and prediction is made from the acceleration of vibration obtained by referring to this map.

  Then, the process proceeds from step S5 to step S6, the torque-down timing and the torque-down amount for temporarily reducing the engine torque are set based on the predicted amplitude and cycle of the vehicle longitudinal vibration, and the routine is exited. Torque down timing is based on the point in time when the step increase in engine torque corresponding to the depression of the accelerator pedal is started, so that the time from this reference is the time for the first peak in the amplitude waveform of the longitudinal vibration to appear. In addition, a torque down start time and a torque down period (or end time) are set.

  Specifically, the torque down timing is determined based on the time when the acceleration condition for executing the vibration damping control is satisfied, the time when the control command for the throttle opening is output from the ETC 20, or the like. The torque down amount is set by mapping in advance the relationship between the amplitude and period of the vehicle longitudinal vibration and the torque down amount according to the vehicle characteristics including the engine characteristics, and referring to the map. Although it is set, there is a limit value that is naturally determined by vehicle characteristics including engine characteristics.

  If the torque reduction amount is limited, it is expected that a sufficient damping effect cannot be obtained by only one torque reduction just before the first peak in the amplitude waveform of the longitudinal vibration appears. The torque down timing is also set for the next peak of the amplitude waveform.

  The torque-down timing and the torque-down amount set in the torque-down setting routine described above are referred to in the ignition timing control, and the ignition timing is retarded and the torque is reduced before the vehicle longitudinal vibration substantially occurs. Vibration is suppressed.

  Next, an example of ignition timing control including ignition timing retarding of vibration suppression control will be described using the flowchart of FIG. Note that the ignition timing setting routine shown in FIG. 4 shows an example of the ignition timing setting, and is not necessarily limited to this.

  In the ignition timing setting routine of FIG. 4, in the first step S10, the basic ignition timing ADVB is set according to the operating state. The basic ignition timing ADVB is set with reference to a table based on, for example, the engine speed and the engine load (basic fuel injection pulse width, etc.).

  Next, it progresses to step S11 and it is investigated whether it is the torque down timing which implements the damping control at the time of acceleration. If it is not the torque down timing, the routine proceeds from step S11 to steps S12, S13 to execute normal ignition timing control. If the torque down timing is reached, the routine proceeds from step S11 to steps S14, S15, and ignition for vibration suppression control. Perform timing retarding.

  In normal ignition timing control, in step S12, various correction values ADVH for correcting the basic ignition timing ADVB are set. The various correction values ADVH collectively refer to various correction values such as knocking correction, water temperature correction, rotation speed correction, and learning correction. Specifically, each correction value is individually set. In step S13, the basic ignition timing ADVB is corrected with various correction values ADVH, and the final ignition timing ADV is set.

  On the other hand, when the accelerator pedal is depressed for acceleration to shift to an operation state in which vibration suppression control is executed and the torque down timing is reached, a torque down correction value ADVTD is set in step S14. The torque-down correction value ADVTD is a retard amount that decreases the engine torque by the torque-down amount set in the torque-down setting routine, and is set according to the engine characteristics within a range that does not cause misfire. In step S15, the basic ignition timing ADVB is retarded with the torque-down correction value ADVTD, and the final ignition timing ADV is set.

  The torque-down correction value ADVTD may be set in the torque-down setting routine, and the torque-down correction value ADVTD may be simply read in the ignition timing setting routine.

  As described above, when the final ignition timing ADV is set, the spark plug 17 is sparked via the igniter 18 at the ignition timing ADV, and the combustion cycle of the engine is repeated. At this time, when the vibration suppression control during acceleration is performed, the ignition timing ADV is retarded by the torque down correction value ADVTD, and acts as a reverse phase torque with respect to the torsional vibration of the drive system.

  As shown in FIG. 5, this reverse-phase torque reduces the engine torque (input) F, which increases stepwise, at least before the first peak appears with respect to the predicted amplitude waveform of the longitudinal vibration. Is given by. Since the waveform of the transmission force F1 is equal to the waveform of the vehicle longitudinal acceleration A2, the predicted longitudinal vibration is shown by the broken line waveform of the transmission force F1 in FIG.

  As a result, as shown in FIG. 5, it is possible to suppress the longitudinal vibration during acceleration and to obtain the vehicle acceleration as shown by the bold line in the figure, and to suppress the shock by suppressing the peak of the first vibration side of the longitudinal vibration. In addition to alleviating, the feeling of vibration generated during the vibration damping process is reduced, and the driver is not uncomfortable.

  In addition, since the reverse phase torque is applied at least before the first peak appears in the amplitude waveform of the longitudinal vibration, the rise of the vehicle acceleration corresponding to the accelerator operation does not slow down and the acceleration feeling is not impaired, but rather a smooth acceleration fee A ring can be obtained, which can contribute to improvement in drivability.

Schematic configuration diagram showing the vehicle control system Explanatory drawing showing the torsional resonance model of the drive system Torque down setting routine flowchart Flow chart of ignition timing setting routine Explanatory diagram showing the relationship between engine torque and vehicle longitudinal vibration

Explanation of symbols

1 Vehicle 2 Engine 3 Transmission 50 Electronic Control Unit ADV Ignition Timing ADVTD Torque Down Correction Value

Claims (3)

In a vehicle vibration suppression device that suppresses vibration generated in a drive system of a vehicle with engine torque having a phase opposite to the vibration,
Longitudinal vibration prediction means for predicting longitudinal vibration generated during acceleration of the vehicle, based on a model expressing the torsional elements of the drive system as a spring system;
Torque down timing setting means for setting the timing for applying the reverse phase engine torque to an initial stage where the longitudinal vibration starts based on the prediction result of the longitudinal vibration prediction means;
A negative phase torque generating means for generating the negative phase engine torque by retarding the engine ignition timing at a timing set by the torque down timing setting means and reducing the engine torque; A vehicle vibration suppression device. The torque down timing setting means includes:
2. The vehicle vibration suppression according to claim 1, wherein the timing of applying the reverse phase engine torque is set at least before the first peak appears in the amplitude waveform of the longitudinal vibration predicted by the longitudinal vibration prediction means. apparatus. The longitudinal vibration prediction means is
3. The vehicle vibration suppressing device according to claim 1, wherein the longitudinal vibration is predicted in consideration of an engine torque fluctuation amount during acceleration and a transmission gear stage.

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