JP2023076929A - Control device of vehicle - Google Patents

Abstract

To provide a control device of a vehicle which can restrain vibration.SOLUTION: A control device of a vehicle, in which output torque of a drive power source is transmitted to driving wheels via a non-stage transmission and a drive shaft, comprises: a detection part which detects switching from on-accelerator to off-accelerator; a prediction part which, upon the detection part detecting the switching from the on-accelerator to the off-accelerator, predicts a transmission gear ratio of the non-stage transmission as of when the output torque functions, as a requested torque corresponded to the off-accelerator; a calculation part which calculates an inverse number of a resonant frequency generated at the transmission gear ratio predicted by the prediction part, of a drive system which contains from the drive power source to the drive shaft; and a control part which controls the drive power source so that a torque falling time period becomes the inverse number of the resonant frequency, the torque falling time period ranging from when the switching from the on-accelerator to the off-accelerator is detected by the detection part until when the output torque becomes the requested torque.SELECTED DRAWING: Figure 4

Description

The present invention relates to a vehicle control device.

There is a technique for suppressing vehicle vibration by setting the reciprocal of the resonance frequency of a driving system including a driving force source and a transmission as the torque fall time of the driving force source (see Patent Document 1, for example).

JP 2019-099059 A

If the transmission is a continuously variable transmission, the gear ratio continuously changes even during the torque drop. If the reciprocal of the resonance frequency is used as the torque fall time without considering such a gear ratio, vibration may not be sufficiently suppressed.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a vehicle control apparatus capable of suppressing vibration.

The object is to provide a control device for a vehicle in which output torque of a driving force source is transmitted to driving wheels via a continuously variable transmission and a drive shaft, wherein a detecting unit for detecting switching from accelerator-on to accelerator-off; a prediction unit for predicting a gear ratio of the continuously variable transmission when the output torque becomes a required torque corresponding to the accelerator-off when the detection unit detects the switching from the accelerator-on to the accelerator-off; A calculation unit that calculates the reciprocal of a resonance frequency of a driving system including from the driving force source to the drive shaft that occurs at the gear ratio predicted by the prediction unit, and the detection unit detects switching from accelerator ON to accelerator OFF. and a control unit for controlling the driving force source such that the torque fall time from when the output torque reaches the required torque is the reciprocal of the resonance frequency. can.

ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the vehicle which can suppress a vibration can be provided.

FIG. 1 is a block diagram showing a schematic configuration of a vehicle according to this embodiment. FIG. 2 is a graph showing the relationship between vibration intensity and frequency. FIG. 3 is a graph showing the relationship between drive shaft torque and torque fall time. FIG. 4 is an example of a timing chart showing changes in accelerator opening, transmission gear ratio, and engine torque. FIG. 5 is a flowchart showing an example of vibration suppression control executed by the ECU. FIG. 6A is an example of a map that defines the relationship between the gear ratio and the resonance frequency, and FIG. 6B is a map that defines the resonance frequency and the torque fall time.

[Schematic configuration of vehicle]
FIG. 1 is a block diagram showing a schematic configuration of a vehicle 1 of this embodiment. As shown in FIG. 1, a vehicle 1 includes an engine (ENG) 10, a torque converter (T/C) 20, a continuously variable transmission (CVT) 30, a hydraulic control circuit 35, a differential gear 41, a drive shaft 43, drive wheels 45, and an ECU (Electronic Control Unit) 50.

The engine 10 is a driving force source for the vehicle 1 . The engine 10 is a gasoline engine, which is an example of an internal combustion engine, but is not limited to this, and may be a diesel engine. Torque of engine 10 is transmitted to driving wheels 45 through torque converter 20 and continuously variable transmission 30 .

The torque converter 20 is a hydrodynamic power transmission device, and includes a pump impeller directly or indirectly connected to the crankshaft of the engine 10 described above, and a turbine runner connected to the input shaft of the torque converter 20. ing. The torque converter 20 increases and transmits torque, which is power, from the pump impeller side to the turbine runner side via oil.

Continuously variable transmission 30 is arranged on the same axis as engine 10 as shown in FIG. 1 and transmits torque between engine 10 and drive wheels 45 . The continuously variable transmission 30 can continuously change the gear ratio, which is the ratio of the input rotation speed to the output rotation speed. Specifically, the gear ratio can be changed by changing the groove width of the input side pulley and the output side pulley by the hydraulic control circuit 35 controlled by the ECU 50, thereby changing the winding diameter of the transmission belt.

A differential gear 41 that is a final reduction gear is connected to an output shaft 31 of the continuously variable transmission 30 , and torque is transmitted to drive wheels 45 via a drive shaft 43 that is connected to the differential gear 41 . The driving wheels 45 generate a driving force on the road surface by the power of the engine 10 transmitted from the torque converter 20 and the continuously variable transmission 30, thereby causing the vehicle 1 to travel. The drive wheels 45 may be left and right front wheels, left and right rear wheels, or both.

The hydraulic control circuit 35 is a known hydraulic control circuit that uses a mechanical oil pump driven by the engine 10 as a hydraulic supply source, and supplies hydraulic pressure to the torque converter 20 and the continuously variable transmission 30 to control their operations. Control. Further, by inputting a hydraulic pressure command value output from the ECU 50 to the hydraulic pressure control circuit 35, each hydraulic pressure supplied to the torque converter 20 and the continuously variable transmission 30 is controlled based on the hydraulic pressure command value.

The ECU 50 is an electronic control unit that performs control processing regarding the vehicle 1 . The ECU 50 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a backup RAM, and the like. The ROM stores various control programs, maps to be referred to when executing the various control programs, and the like. The CPU executes arithmetic processing based on various control programs and maps stored in the ROM. In addition, the RAM is a memory that temporarily stores the calculation results of the CPU and the data input from each sensor, etc., and the backup RAM is a non-volatile memory that stores data that should be saved when the ignition is turned off. . The CPU, ROM, RAM, and backup RAM functionally implement a detection unit, a prediction unit, a calculation unit, and a control unit, which will be described later in detail.

Various sensors and switches such as an ignition switch 60, a crank angle sensor 61, an accelerator opening sensor 62, and an output shaft rotation speed sensor 63 are connected to the ECU 50, and signals from these sensors and switches are sent to the ECU 50. is entered. The ECU 50 controls the operating state of the engine 10 and the gear ratio of the continuously variable transmission 30 based on the detection results of various sensors.

[Relationship between resonance frequency and torque fall time]
In the vehicle 1 configured as described above, the drive system from the engine 10 to the drive shaft 43 may resonate due to torque fluctuations of the engine 10 . FIG. 2 is a graph showing the relationship between vibration intensity [dB] and frequency [Hz]. The vertical axis indicates vibration intensity, and the horizontal axis indicates frequency. In FIG. 2, the case of the gear ratio γ0 of the continuously variable transmission 30 is indicated by a dotted line, and the case of the gear ratio γ1 smaller than the gear ratio γ0 is indicated by a solid line. The frequency at the peak value of vibration intensity is the resonance frequency. As shown in FIG. 2, the resonance frequency f0 at the gear ratio γ0 is lower than the resonance frequency f1 at the gear ratio γ1. In other words, the smaller the gear ratio, the higher the resonance frequency tends to be. This is because the smaller the gear ratio, the smaller the difference in the rotational speed of the drive shaft 43 with respect to the engine rotational speed, which is equivalent to the higher rigidity of the drive system from the crankshaft of the engine 10 to the drive shaft 43 . In the case of the continuously variable transmission 30, the gear ratio is controlled to be small at low vehicle speeds, and is controlled to be large at high vehicle speeds.

When the torque of the engine 10 drops due to the switching from accelerator-on to accelerator-off, vibration due to resonance as described above may occur. The torque of the drive shaft 43 at the time of torque fall (hereinafter referred to as drive shaft torque) fluctuates according to the torque fall time. If the drive shaft torque fluctuates significantly, the vehicle 1 vibrates. The torque fall time is the time from when the ECU 50 detects that the accelerator has been switched from on to off until the torque of the engine 10 reaches the required torque corresponding to the off of the accelerator.

FIG. 3 is a graph showing the relationship between drive shaft torque [N·m] and torque fall time [s]. The vertical axis indicates the drive shaft torque, and the horizontal axis indicates the torque fall time. As shown in FIG. 3, it is known that the drive shaft torque has a waveform that takes the absolute value of a sine wave, and that the drive shaft torque becomes zero when the torque fall time is an integer multiple of the reciprocal of the resonance frequency. . Specifically, in the case of the gear ratio γ0, the drive shaft torque becomes zero when the torque fall time is (1/f0), (2/f0), (3/f0), and so on. Similarly, when the gear ratio is γ1, the drive shaft torque becomes zero when the torque fall time is (1/f1), (2/f1), (3/f1), and so on. The shortest torque fall times at which the drive shaft torque becomes zero at gear ratios γ0 and γ1 are (1/f0) and (1/f1), respectively, and (1/f1)<(1/f0) holds. do. The peak value of the adjacent drive shaft torques at the gear ratios γ0 and γ1 is smaller at the gear ratio γ1 than at the gear ratio γ0.

FIG. 3 shows the torque D0 when the torque fall time is (1/f0) at the gear ratio γ0 and the torque fall time (1/f0) at the gear ratio γ1. and torque D1 in the case. Torque D0 is zero and torque D1 is a value greater than torque D0. Details will be described later.

[Setting of Torque Fall Time Considering Transition of Gear Ratio]
FIG. 4 is an example of a timing chart showing transitions of accelerator opening [deg], gear ratio [-], and engine torque [N·m]. The engine torque is an example of the output torque of the drive power source. In order to facilitate understanding, FIG. 4 illustrates a case where the gear ratio γ0 is lowered to the gear ratio γ1 due to the torque drop. At time t0, the vehicle is running at a predetermined accelerator opening and a gear ratio γ0. When it is detected that the accelerator is off at time t1, the gear ratio gradually decreases along with the engine torque. Ultimately, the engine torque is reduced to a predetermined deceleration torque corresponding to accelerator off, and the gear ratio is reduced to the gear ratio γ1.

Here, a comparative example shown in FIG. 4 will be described. In the comparative example, the torque fall time is set to (1/f0) based on the gear ratio γ0 at time t1 when the accelerator is detected. Therefore, at time t3 when (1/f0) has passed from time t1, the engine torque becomes the backlash reduction start torque, and the gear ratio decreases from the gear ratio γ0 to the gear ratio γ1. That is, the gear ratio when the engine torque becomes the backlash reduction start torque is not the gear ratio γ0 but the gear ratio γ1. Therefore, in the comparative example, when the engine torque reaches the rattling start torque, the torque D1 shown in FIG.

In this embodiment, it is predicted that the gear ratio when the engine torque reaches the backlash reduction start torque at time t1 will be the gear ratio γ1, and the torque fall time is set to (1/f1) based on the gear ratio γ1. set to Therefore, in this embodiment, the engine torque becomes the backlash reduction start torque at time t2 after (1/f1) from time t1. The drive shaft torque at this time is zero as shown in FIG. Vibration is suppressed in this way.

[Vibration suppression control]
FIG. 5 is a flowchart showing an example of vibration suppression control executed by the ECU 50. As shown in FIG. This control is repeatedly executed with the ignition on. The ECU 50 determines whether or not it has detected that the accelerator has been switched from on to off (step S1). If No in step S1, this control ends. Step S1 is an example of processing executed by the detection unit.

In the case of Yes in step S1, the ECU 50 predicts the gear ratio when the engine torque becomes the required torque corresponding to the accelerator off (step S2). Specifically, the ECU 50 predicts the target gear ratio set based on the detection of accelerator off as the above gear ratio. The target gear ratio is set by the current output shaft speed and the target engine speed. Note that the gear ratio prediction method is not limited to this. For example, the gear ratio may be predicted by referring to a map of adaptive values experimentally calculated based on the current output shaft speed and target engine speed. Step S2 is an example of processing executed by the prediction unit.

Next, the ECU 50 calculates the resonance frequency based on the predicted gear ratio (step S3). FIG. 6A is an example of a map that defines the relationship between gear ratios and resonance frequencies. In this map, as described above, the smaller the gear ratio, the higher the resonance frequency. This map is calculated in advance by experiments and stored in the memory of the ECU 50 . The ECU 50 refers to this map to calculate the resonance frequency.

Next, the ECU 50 calculates the torque fall time based on the calculated resonance frequency (step S4). FIG. 6B is a map that defines resonance frequency and torque fall time. As described above, this map defines that the higher the resonance frequency, the shorter the torque fall time. This map is stored in the memory of the ECU 50 in advance. The ECU 50 refers to this map to calculate the torque fall time. Steps S3 and S4 are an example of processing executed by the calculation unit. As described above, since the torque fall time is the reciprocal of the resonance frequency, it may be calculated without referring to the map as described above.

Next, the ECU 50 reduces the engine torque so that the engine torque becomes the required torque corresponding to the accelerator off when the torque fall time has elapsed after the accelerator off is detected (step S5). For example, the ECU 50 adjusts the reduction amount of the intake air amount of the engine 10 and the retardation amount of the ignition timing, and reduces the engine torque to the required torque after the torque fall time has passed since the accelerator is turned off. Step S5 is an example of processing executed by the control unit.

In the above embodiment, the ECU 50, which is the control device of the vehicle 1 whose driving force source is the engine 10, was described as an example, but the present invention is not limited to this. For example, the contents of the above embodiments can be applied to a control device for an electric vehicle having a motor as a driving force source, and a control device for a hybrid vehicle having an engine and a motor as driving force sources.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations can be made within the scope of the gist of the present invention described in the scope of claims. Change is possible.

10 engine 50 ECU (control device, detection unit, prediction unit, calculation unit, control unit)

Claims (1)

A control device for a vehicle in which output torque of a driving force source is transmitted to driving wheels via a continuously variable transmission and a drive shaft,
a detection unit that detects switching from accelerator-on to accelerator-off;
a prediction unit that predicts a gear ratio of the continuously variable transmission when the output torque becomes a required torque corresponding to the accelerator-off when the detection unit detects switching from the accelerator-on to the accelerator-off;
a calculation unit that calculates the reciprocal of a resonance frequency of a driving system including from the driving force source to the drive shaft that occurs at the gear ratio predicted by the prediction unit;
The driving force source is controlled such that the torque fall time from when the detection unit detects switching from accelerator-on to accelerator-off until the output torque reaches the required torque is the reciprocal of the resonance frequency. and a controller for a vehicle.

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