KR101021116B1 - Motor torque control method of hybrid vehicle - Google Patents

Abstract

The present invention relates to a motor torque control method of a hybrid vehicle, and more particularly, to control motor torque in consideration of a backlash of a gear engaged between a transmission and a drive shaft during tip-in / out driving of a parallel hybrid vehicle without a torque converter. Therefore, the present invention relates to a method of controlling motor torque of a hybrid vehicle in which shock and jerk phenomena are reduced to improve driving and riding comfort.

To this end, the present invention comprises the steps of determining the tip-in driving; Controlling the motor torque using a motor torque profile in consideration of the backlash between the drive side gear, which is an automatic transmission side gear, and the tire side gear, which is a drive shaft side gear; It provides a motor torque control method of a hybrid vehicle comprising a.

Hybrid, Motor, Torque Control, Tip-In, Short & Jerk, Drive Shaft, Gear, Backlash

Description

Method for controlling motor torque of hybrid vehicle

The present invention relates to a motor torque control method of a hybrid vehicle, and more particularly, to control motor torque in consideration of a backlash of a gear engaged between a transmission and a drive shaft during tip-in / out driving of a parallel hybrid vehicle without a torque converter. Therefore, the present invention relates to a method of controlling motor torque of a hybrid vehicle in which shock and jerk phenomena are reduced to improve driving and riding comfort.

The hybrid vehicle is a future vehicle that can adopt a motor driving source as an auxiliary power source as well as an engine, and can reduce exhaust gas and improve fuel efficiency, and can be divided into a series type or a parallel type according to the arrangement of the power transmission device.

Looking at the system configuration of the parallel hybrid vehicle, as shown in the configuration diagram of Figure 1, the engine 10, the motor 20, the automatic transmission 30 is directly connected on one axis, the engine 10 and The motor 20 is connected by the clutch 40, and the automatic transmission is connected to transmit power to the drive shaft 60, and of course, the crank of the engine by the inverter, the belt for their operation ISG (50, Integrated Starter Generator (ISG)), high voltage battery and the like directly connected to the pulley.

Such a hybrid hybrid vehicle (HEV) is a case in which an automatic transmission in which a torque converter is deleted is applied, and there is a lack of attenuating vibration factor compared to a conventional gasoline automatic transmission vehicle due to the removal of the torque converter, and thus shock and jerk during creep driving. (Shock & Jerk) There is a problem that occurs.

In the hybrid vehicle, the torque amount of the drive motor is determined by the opening ratio of the throttle valve, which is the amount of the accelerator pedal, which is the driver's driving demand, and the current vehicle speed. In the case of tip-in / out, the torque change of the motor also changes rapidly in response to this. Therefore, if the accelerator pedal is repeatedly tip-in / out rapidly, the vehicle shakes due to the sudden change in the amount of motor torque. The shock and jerk phenomenon occurs to cause a problem of deterioration of ride comfort.

As shown in the accompanying FIG. 3, in which a hybrid vehicle compares a power transmission device of a general gasoline vehicle, a general gasoline vehicle has a torque converter that damps a driving system, and thus has a tip-in / out tip. Shock and jerk is not a big problem in the case of -in / out.However, in the case of hybrid vehicles, the torque converter is deleted to improve fuel efficiency, so there is no mechanism for damping. The shock and jerk phenomenon caused by tip-in / out is severely generated.

In addition, the shock and jerk phenomenon occurs mainly when creep oscillation due to the backlash accumulation of transmission gears, and the shock and jerk phenomenon generated during the creep oscillation are the next-generation eco-friendly vehicles. Contrary to their image, they have a very bad effect on the overall driving performance of the vehicle.

Here, look at the phenomenon that the gear backlash occurs during the coasting and tip-in driving as follows.

4 is a graph showing motor torque and drive shaft (D / S) torque during time (ms) during tip-in driving.

It takes a certain time for the motor torque to be transmitted to the drive shaft, which may be described as the time required for the gear inside the automatic transmission to be aligned in the driving direction, that is, the delay time due to the gear backlash.

Accordingly, due to the time delay caused by the gear backlash, as shown in the drive shaft torque diagram of FIG. 4, a fluctuation phenomenon occurs in the torque of the drive shaft, which causes shock and jerk. It becomes the cause of generation.

The delay time due to the gear backlash will be described in more detail with reference to FIG. 5.

While driving on the other side by the acceleration force of the vehicle, the frictional force with the ground acts on the tire gear (drive shaft gear) and the driving gear (automatic gear gear) acts as a load. As the gear tooth is transferred from the tire gear to the driving gear, the driving gear is located on the left side as shown in FIG. 5, and the driving gear and the tire gear rotate to the right at the same speed.

In this state, when the tip-in phase for rapidly stepping on the accelerator pedal is started, additional force is transmitted to the driving gear by the motor driving, and the driving gear is no load in the driving direction, so The speed of the side gear starts to increase relative to the speed of the tire side gear, so that the driving side gear is moved to the right relative to the tire side gear.

Subsequently, the tip-in phase is terminated and the drive travel is performed, as shown in the bottom view of FIG. 5, where the drive side gear moves the gear clearance so as to contact the tire side gear on the right side. Subsequently, the driving force starts to be transmitted to the tire through the tire-side gear, and when a driving force greater than the frictional force is transmitted, the vehicle speed increases to drive driving.

Here, the gap between the drive gear (automatic transmission gear) and the tire gear (drive shaft gear) as described above, that is, the phenomenon of shock and jerk due to backlash, will be described with reference to FIG. Same as

When switching from coasting to tip-in driving, a delay occurs while the drive gear moves to the tire gear, and during this delay, the motor torque is not transmitted to the tire gear through the drive gear.

In this way, the motor torque is not transmitted to the drive shaft during the time that the driving gear is brought into contact with the tire gear during tip-in driving, and at the moment when the driving gear touches the tire gear, motor torque of about 30 Nm or more is applied to the drive shaft. It is applied suddenly, which is about 420 Nm in terms of drive shaft torque, and this sudden torque transmission causes short and jerk on the drive shaft.

The occurrence of such a shock and jerk phenomenon leads to a problem of deterioration of ride comfort and driving ability, and therefore, shocks generated during the starting and driving of a vehicle directly related to the driving performance of a hybrid vehicle ( The study of shock reduction is the main item in the development of hybrid vehicles.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and in the tip-in / out driving of a parallel hybrid vehicle without a torque converter, the motor torque is controlled by considering the backlash of the gear engaged between the transmission and the drive shaft. It is an object of the present invention to provide a method for controlling motor torque of a hybrid vehicle in which a sudden torque is not transmitted, thereby reducing shock and jerking caused by torque shaking of the drive shaft, thereby improving driving comfort and riding comfort.

The present invention for achieving the above object comprises the steps of: determining the tip-in driving; Controlling the motor torque using a motor torque profile in consideration of the backlash between the drive side gear, which is an automatic transmission side gear, and the tire side gear, which is a drive shaft side gear; It provides a motor torque control method of a hybrid vehicle comprising a.

In a preferred embodiment, the step of controlling the motor torque using the motor torque profile comprises: when it is determined that the tip-in driving is performed, each tooth of the drive side gear contacts each tooth of the tire side gear. Increasing the motor torque during the time it travels to become; Reducing the motor torque for a predetermined time when each tooth of the drive side gear is in contact with each tooth of the tire side gear; The process of continuously increasing the motor torque in accordance with the driver's will to step on the accelerator pedal; Characterized in that consists of.

Through the above problem solving means, the present invention can provide the following effects.

According to the present invention, in consideration of the backlash of the gear engaged between the transmission and the drive shaft during tip-in / out driving of a parallel hybrid vehicle, the gear backlash is reduced by controlling the motor torque to be temporarily increased, and the gear of the transmission side By reducing the torque of the motor at the moment of contact with the gear on the drive shaft side, the sudden torque is not transmitted to the drive shaft, thereby reducing the shock and jerk phenomenon caused by the torque shake phenomenon of the drive shaft. Can improve.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention prevents rapid transfer of motor torque to the drive shaft by controlling the motor torque in consideration of the backlash of the gear engaged between the transmission and the drive shaft during tip-in / out driving of a parallel hybrid vehicle without a torque converter. The main focus is to reduce the shock and jerk caused by the vibration of the drive shaft, thereby improving driving and riding comfort.

7 is a graph illustrating the reduction of the torque shaking phenomenon of the drive shaft by the motor torque control method according to the present invention, FIG. 8 is a flowchart illustrating the motor torque control method according to the present invention, and FIG. In the motor torque control method according to the present invention, it is a graph showing the motor torque profile in consideration of the gear backlash.

The hybrid vehicle is driven by the EV mode when switching from the other driving to the tip-in driving or when creep driving (the slow driving after the stop is called creep driving).

According to the present invention, it is determined that the tip-in driving while driving or stopping, and if it is confirmed that the tip-in driving, the motor torque profile considering the backlash between the gear on the drive side of the automatic transmission gear and the gear on the tire side of the drive shaft gear It is characterized by controlling the motor torque by using a.

Here, the torque profile for the motor torque control according to the present invention will be described.

First, when it is determined that tip-in driving is performed while driving or stopping in the main vehicle, such as HCU, which is the main controller of the hybrid vehicle, the tip-in driving is performed, a torque control command is given to the motor to perform the acceleration / deceleration control for the motor torque.

At this time, before the tip-in driving (before the motor torque control command is issued), the drive side gear, which is the automatic transmission gear, and the tire gear, which is the drive shaft gear, are in a state of generating backlash, that is, a gear gap.

That is, as shown in the uppermost drawing in FIG. 5, the gear gap between the teeth of the gear on the tire side is generated as much as the tolerance in gear production.

Accordingly, the gear gap, ie, the gear backlash, is reduced through the control of temporarily increasing the motor torque with the tip-in driving.

More specifically, as shown in FIG. 9, at the time of tip-in determination, the motor torque command of m1 Nm is issued and the torque of m1 Nm is maintained for t1 seconds to reduce the gear gap. do.

Thus, by increasing the motor torque during the time that each tooth of the drive side gear moves to contact each tooth of the tire side gear, the gear backlash is reduced.

Subsequently, as soon as the driving gear of the automatic transmission gear reaches the tire gear of the gear of the drive shaft, the sudden torque is not transmitted to the drive shaft through a control that reduces the motor torque.

More specifically, the moment when the drive gear of the automatic transmission gear reaches the tire gear of the drive shaft gear, the motor torque command of m2 Nm is reduced as the reduced magnitude, and the torque of the reduced m2 Nm magnitude is applied for t2 seconds. To minimize motor torque when the drive gear contacts the tire gear.

As such, when the teeth of the gear on the driving side are in contact with the teeth of the gear on the tire side, the motor torque is suddenly moved toward the drive shaft as before. The transmission may prevent the phenomenon in which the torque of the drive shaft is generated up to a level of 420 Nm, and as a result, as shown in the third graph of FIG.

Thereafter, the motor torque is continuously increased in accordance with the driver's intention to step on the accelerator pedal, thereby driving the vehicle normally.

On the other hand, the magnitude of increase (m1 Nm) and decrease (m2 Nm) of the motor torque, the torque holding time (t1, t2) is mapped according to the gear gap, vehicle speed (motor speed), APS (acceleration pedal position) of the hybrid vehicle The main controller can be stored in the memory of the HCU, and the gear gap is constant for each gear stage, and thus can be obtained experimentally.

1 is a block diagram for power transmission of a parallel hybrid vehicle,

2 is a graph illustrating a shock and jerk phenomenon according to tip-in / out driving;

3 is a configuration diagram comparing the power transmission device of a hybrid vehicle and a general gasoline vehicle,

4 is a graph illustrating that shock and jerk shapes are generated by excessive torque acting on the drive shaft due to gear backlash during tip-in driving;

5 is a schematic diagram illustrating a gear backlash phenomenon;

6 is a graph illustrating a short and jerk phenomenon in the drive shaft due to the gear backlash phenomenon of FIG. 5;

7 is a graph illustrating the reduction of the torque shaking phenomenon of the drive shaft by the motor torque control method according to the present invention;

8 is a flowchart illustrating a motor torque control method according to the present invention;

9 is a graph showing a motor torque profile in consideration of the gear backlash in the motor torque control method according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10: engine 20: motor

30: automatic transmission 40: clutch

50: ISG 60: drive shaft

Claims (4)

delete delete Determining tip-in driving; Controlling the motor torque using a motor torque profile in consideration of the backlash between the drive side gear, which is an automatic transmission side gear, and the tire side gear, which is a drive shaft side gear; In the motor torque control method of a hybrid vehicle comprising: Controlling the motor torque using the motor torque profile includes: When it is confirmed that the vehicle is a tip-in driving, the motor torque increases to the size of m1 Nm during the time (t1 second) during which each tooth of the drive side gear moves to contact each tooth of the tire side gear. Process; At the moment when each tooth of the drive gear is in contact with each tooth of the tire gear, reducing the motor torque by m2 Nm for a predetermined time (t2 seconds); The process of continuously increasing the motor torque in accordance with the driver's will to step on the accelerator pedal; Motor torque control method of a hybrid vehicle, characterized in that consisting of. The method of claim 3, The increase (m1 Nm) and decrease (m2 Nm) of the motor torque, and the torque holding time (t1, t2) can be mapped to the gear gap, vehicle speed (motor speed), APS (acceleration pedal position) and stored in the controller. And the gear gap is constant according to each gear stage, and thus is experimentally determined.

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