JP4604815B2 - Vehicle drive control device - Google Patents

Description

  The present invention relates to a vehicle drive control device capable of driving wheels with an electric motor.

Conventionally, there are motors that drive the main drive wheels by the engine and drive the auxiliary drive wheels by the electric motor when the slip tendency of the main drive wheels is detected. The driving force of the electric motor is increased on the uphill road than on the flat road. In addition, it has been proposed to drive the electric motor according to the driver's accelerator operation even when the main driving wheel does not tend to slip during low-speed traveling (see Patent Document 1).
JP 2002-218605 A

  By the way, when starting on an uphill road with a steep slope, if the engine torque (creep torque) is insufficient, the vehicle may move backward until the brake is released and the accelerator is depressed (hereinafter referred to as rollback). On dry roads with a high coefficient of friction μ, even if you roll back, you can move straight forward by stepping on the accelerator. Therefore, it is desirable to drive the auxiliary driving wheel.

However, in the conventional example described in Patent Document 1, since the motor torque is not generated until the driver steps on the accelerator or until the slip tendency of the main driving wheel is detected, the response is delayed and the rollback is effective. Cannot be suppressed.
Therefore, the present invention has been made paying attention to the above problem, and an object of the present invention is to provide a vehicle drive control device that can quickly suppress rollback.

In order to solve the above-described problems, a vehicle drive control device according to the present invention is a vehicle drive control device capable of driving wheels by an electric motor, and detects a rollback in which the vehicle moves in the direction opposite to the traveling direction. And a drive control means for increasing the driving force in the vehicle traveling direction in the electric motor when the rollback of the vehicle is detected by the rollback detection means than when the rollback is not detected. It is said.
Further, when the drive control means increases the driving force of the electric motor in the vehicle traveling direction, and the rollback speed decreases, the driving control means increases the driving force in the vehicle traveling direction when the rollback speed decreases. It is characterized by maintaining.

According to the present invention, when the vehicle moves in the direction opposite to the traveling direction, that is, when the vehicle rolls back, the rollback is performed by immediately increasing the driving force in the vehicle traveling direction in the electric motor without waiting for the driver's accelerator operation. It can be quickly suppressed.
Further, by maintaining the driving force in the vehicle traveling direction at the time when the rollback speed is reduced, it is possible to reliably prevent the vehicle from rolling back again and improve the starting performance.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a first embodiment of the present invention, in which front wheels 1FL and 1FR are main drive wheels driven by an engine 2 (internal combustion engine), and rear wheels 1RL and 1RR are electric motors 3 (electric motors). This is a so-called standby type four-wheel drive vehicle that can be driven auxiliary drive wheels.
The output of the engine 2 is transmitted to the front wheels 1FL and 1FR via the automatic transmission 4 having a torque converter, and the output of the electric motor 3 fed by the battery 5 is transmitted to the rear wheels 1RL and 1RR via the speed reducer 6. Is transmitted to.

The electric motor 3 is driven and controlled by the controller 7, and usually the vehicle speed is within a predetermined range (for example, 0 to 0) even when the slip tendency of the front wheels 1FL and 1FR is detected or even when the slip tendency of the front wheels 1FL and 1FR is not detected. When the vehicle is traveling at a low speed of 30 km / h, a motor torque Tm corresponding to the driver's accelerator operation is output.
The controller 7 includes a shift position signal of the automatic transmission 4 detected by the inhibitor switch 10, rotation speed and rotation direction signals of the wheels 1 FL to 1 RR detected by the rotation sensor 11, and a driver's accelerator detected by the accelerator sensor 12. An operation signal is input.

Next, drive control processing executed by the controller 7 will be described with reference to the flowchart of FIG.
First, in step S1, it is determined whether or not the vehicle is rolling back. Specifically, when the wheel rotates in the vehicle reverse direction with the shift position in the forward range such as “D” or “1”, or when the shift position is in the reverse range of “R” When the vehicle is rotating in the vehicle forward direction, it is determined that the vehicle is rolling back, and the process proceeds to step S3 described later. Otherwise, it is determined that the vehicle is not rolled back and the process proceeds to step S2. .

  In step S2, referring to the control map of FIG. 3, the generation of the motor torque Tm is controlled based on the front wheel slip tendency and the accelerator operation, and then the process returns to a predetermined main program. Here, the front wheel slip tendency is calculated by, for example, calculating the front wheel slip speed by subtracting the average wheel speed of the rear wheel from the average wheel speed of the front wheel, and when the front wheel slip speed is greater than 0, the front wheel tends to slip. When the front wheel slip speed is 0 or less, it is determined that the front wheel does not have a slip tendency. According to the control map of FIG. 3, when the front wheel does not tend to slip, when the accelerator operation is ON, the motor torque Tm corresponding to the accelerator operation is generated, and conversely, when the accelerator operation is OFF, the motor torque Tm is generated. Set to zero.

  On the other hand, when the front wheels tend to slip, when the accelerator operation is ON, a motor torque Tm corresponding to the accelerator operation is generated. Conversely, when the accelerator operation is OFF, a predetermined motor torque Tm1 is generated. This motor torque Tm1 is a creep torque that rotates the rear wheels in the vehicle traveling direction in order to compensate for the decrease in the starting performance due to the slip tendency of the front wheels. For example, when the speed reducer 6 with a reduction ratio R = 27 is used, Tm1 is set to about 1.2 [N · m].

  In step S3, referring to the control map of FIG. 4, the generation of the motor torque Tm is controlled based on the front wheel slip tendency and the accelerator operation, and then the process returns to the predetermined main program. According to the control map of FIG. 4, when the front wheel does not tend to slip, when the accelerator operation is ON, a motor torque Tm corresponding to the accelerator operation is generated, and when the accelerator operation is OFF, a predetermined motor torque Tm2 is generated. generate. The motor torque Tm2 is a creep torque that rotates the rear wheels in the vehicle traveling direction in order to suppress vehicle rollback. Therefore, it is set in consideration of an assumed road surface gradient and vehicle weight. For example, when a reduction gear 6 with a reduction ratio R = 27 is used, it is set to about Tm2 = 25-30 [N · m].

  On the other hand, when the front wheels tend to slip, when the accelerator operation is ON, a motor torque Tm corresponding to the accelerator operation is generated. Conversely, when the accelerator operation is OFF, a predetermined motor torque Tm3 is generated. This motor torque Tm3 is a creep torque that rotates the rear wheels in the vehicle traveling direction in order to suppress rollback of the vehicle and to compensate for a decrease in the starting performance due to the slip tendency of the front wheels. Therefore, it is set in consideration of an assumed road surface gradient and vehicle weight. For example, when the reduction gear 6 having a reduction ratio R = 27 is used, it is set to about Tm3 = 38 [N · m].

As described above, when the rollback is detected, a larger motor torque Tm is generated than when the rollback is not detected, and when the slip tendency of the front wheels is detected, the motor torque is larger than when the slip tendency is not detected. Tm is generated. This is the same when the motor torque Tm corresponding to the accelerator operation is generated. The gain characteristic of the motor torque Tm with respect to the accelerator operation is changed. When the rollback is detected, the motor torque Tm is set more than when it is not detected. The motor torque Tm is increased when the front wheel slip tendency is detected and when the front wheel slip tendency is not detected.
As described above, the process in step S1 corresponds to the “rollback detection unit”, and the processes in steps S2 and S3 correspond to the “drive control unit”.

Next, operations and effects of the first embodiment will be described.
When starting on an uphill road with a steep slope, the driver steps on the accelerator after releasing the brake. At this time, if the force to move backward by its own weight is larger than the force to move forward by the creep torque of the front wheels 1FL and 1FR, the vehicle rolls back between when the brake is released and when the accelerator is depressed. .
Therefore, in the present embodiment, when vehicle rollback is detected based on the shift position of the automatic transmission 4 and the rotation direction of the wheels 1FL to 1RR (determination in Step S1 is “Yes”), the time chart of FIG. Thus, without waiting for the driver's accelerator operation, that is, even when the accelerator operation is OFF, the electric motor 3 is immediately caused to generate a creep torque in the vehicle traveling direction (step S3). Thereby, the rollback (speed and distance) of the vehicle can be quickly suppressed, and the start performance can be improved.

In addition to driving the main drive wheels with the engine 2 and detecting the rollback of the vehicle, the auxiliary drive wheels are driven with the electric motor 3 to make the four-wheel drive, so that the two-wheel drive with the electric motor 3 is achieved. Can also improve the starting performance.
Further, when detecting the rollback and generating the creep torque by the electric motor 3, if the slip tendency of the front wheels 1FL and 1FR is detected, the creep torque is generated larger than when the slip tendency is not detected. Further, the starting performance can be improved.

Thus, when the rollback speed (negative speed in FIG. 5) becomes 0, the creep torque of the electric motor 3 is returned to 0. When the rollback is performed again, the creep torque is generated in the electric motor 3, and this operation is performed by the accelerator operation. Repeat until ON. If the accelerator operation is turned on, motor torque Tm corresponding to the driver's accelerator operation is generated thereafter.
Further, when the front wheel does not have a tendency to slip and the accelerator operation is OFF when the vehicle is not rolled back, the motor torque Tm is set to zero. This is because when the creep torque of the engine 2 and the creep torque of the electric motor 3 are matched on a flat road that does not roll back, the creep speed increases rapidly or becomes excessive after the brake is released.

In the first embodiment, the motor torque Tm is generated from 0 in the electric motor 3 when the rollback of the vehicle is detected. However, the present invention is not limited to this, and a certain amount of motor torque Tm is generated. The motor torque Tm may be increased from the state in which is generated.
In the first embodiment, the magnitude of the motor torque Tm is changed depending on whether or not the front wheels 1FL and 1FR tend to slip. Similarly, whether the rear wheels 1RL and 1RR tend to slip. The magnitude of the engine torque Te may be changed depending on whether or not.

  In the first embodiment, the motor torque Tm is generated in the electric motor 3 when it is detected that the vehicle has rolled back. However, before the vehicle rolls back, it is estimated that the vehicle rolls back. Alternatively, the motor torque Tm may be generated in the electric motor 3. In this case, an acceleration sensor (G sensor) that detects the gradient of the road surface can be applied as the rollback detection means. That is, when it is determined by the acceleration sensor or the like that the vehicle is on a sloped road surface and the vehicle travels in the direction of climbing the slope, the occurrence of rollback is detected and the motor torque Tm is generated in the electric motor 3. You can also.

  Moreover, in said 1st Embodiment, in order to detect the rollback of a vehicle, the rotation speed and the rotation direction of wheel 1FL-1RR are detected by the rotation sensor 11, However, It is not limited to this. Many common wheel speed sensors convert a wheel rotation into a change in magnetic field and pick up the strength and polarity of magnetic flux density with a magnetic detection element, and this cannot detect the direction of rotation. Therefore, the rotation direction of the rear wheels 1RL and 1RR may be detected by determining the polarity of the electromotive force of the electric motor 3, and the rollback of the vehicle may be detected based on this. Therefore, if the wheel can be driven by the electric motor, a sensor capable of detecting the rotation direction of the wheel can be omitted.

Moreover, in said 1st Embodiment, in order to detect the slip tendency of a wheel, the slip speed of a wheel is calculated, However, It is not limited to this. For example, the wheel slip tendency may be detected based on the wheel acceleration obtained by differentiating the wheel speed, the slip ratio calculated from the difference between the vehicle body speed and the wheel speed, or the like.
In the first embodiment, the front wheels 1FL and 1FR are main drive wheels that are driven by the engine 2, and the rear wheels 1RL and 1RR are auxiliary drive wheels that can be driven by the electric motor 3. However, the present invention is not limited to this. Instead of this, the rear wheels 1RL and 1RR may be the main drive wheels, and the front wheels 1FL and 1FR may be the auxiliary drive wheels.

Further, in the first embodiment described above, a single motor type power train (power transmission system) that drives the rear wheels 1RL and 1RR with one electric motor 3 is adopted, but the present invention is not limited to this. Absent. For example, a two-motor system in which each wheel is driven by two electric motors, or a wheel-in motor system in which the motor itself is a driving wheel may be employed.
Moreover, in said 1st Embodiment, although the electric power is supplied to the electric motor 3 with the battery 5, it is not limited to this, You may supply electric power to the electric motor 3 with a capacitor | condenser and a generator. The electric motor 3 may be a direct current motor or an alternating current motor.

In the first embodiment described above, a hybrid system is adopted in which the front wheels are engine-driven and the rear wheels are motor-driven. However, the present invention is not limited to this. In addition, a series hybrid method, a parallel hybrid method, or a series / parallel hybrid (spirit hybrid) method may be adopted. Furthermore, the present invention may be applied to a pure electric vehicle (EV) not equipped with an internal combustion engine.
Furthermore, in the first embodiment, the present invention is applied to a four-wheeled vehicle, but may be applied to a two-wheeled vehicle, a three-wheeled vehicle, or a vehicle having five or more wheels.

Next, a second embodiment of the present invention will be described with reference to FIG.
In the second embodiment, the motor torque Tm generated when the vehicle rollback is detected in the first embodiment described above is controlled according to the rollback speed.
That is, Tm2 and Tm3 in FIG. 4 are made variable in accordance with the rollback speed, and as shown in FIG. 6, the motor torque Tm is increased as the rollback speed (negative speed in the figure) is faster.

Thereby, since the motor torque Tm can be generated without excessive or insufficient with respect to the rollback whose speed changes in accordance with the road surface gradient and the load load, the rollback can be accurately suppressed and the start performance can be improved. .
In the second embodiment, the motor torque Tm is changed continuously and continuously in accordance with the rollback speed. However, the present invention is not limited to this, and the motor is stepped in accordance with the rollback speed. The torque Tm may be changed, and it may be only one stage.
Other functions and effects are the same as those of the first embodiment described above.

Next, a third embodiment of the present invention will be described with reference to FIG.
In the third embodiment, the motor torque Tm generated when the vehicle rollback is detected in the second embodiment described above is controlled in accordance with the climbing slope of the road surface with respect to the vehicle traveling direction.
That is, the climbing gradient of the road surface with respect to the vehicle traveling direction is detected in advance by an acceleration sensor, and Tm2 and Tm3 in FIG. 4 are made variable according to the climbing gradient. As shown in FIG. The motor torque Tm is made larger than the time.

Thereby, since the motor torque Tm without excess and deficiency can be generated with respect to the rollback whose speed changes according to the road surface gradient, the rollback can be accurately suppressed and the start performance can be improved.
In the third embodiment described above, the motor torque Tm is changed separately for the gentle gradient and the steep gradient. However, the present invention is not limited to this, and the motor torque is continuously and continuously variable according to the climb gradient. Tm may be changed.
Other functions and effects are the same as those of the second embodiment described above.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
In the fourth embodiment, when the rollback speed decreases when the motor torque Tm in the vehicle traveling direction is increased in the second embodiment described above, the motor torque Tm at that time is maintained.
Thus, instead of decreasing the motor torque Tm in accordance with the decrease in the rollback speed, the vehicle rolls again by maintaining the motor torque Tm at the time when the rollback speed decreases as shown in FIG. It is possible to reliably prevent back-up and to improve the starting performance.
Other functions and effects are the same as those of the second embodiment described above.

  As described above, when the rollback of the vehicle is detected and the electric motor 3 generates the motor torque Tm, only the output and non-output of the predetermined torque (fixed value) are controlled, the rollback speed, The motor torque Tm may be increased according to the climb gradient, or the motor torque Tm at the time when the rollback speed is decreased may be maintained. In addition, the motor torque Tm at the time when the rollback is stopped is maintained, the motor torque Tm is decreased after the vehicle speed increases to a predetermined creep speed, or the motor torque Tm is generated after a predetermined time from the generation of the motor torque Tm. The torque Tm may be decreased, or the motor torque Tm may be changed according to the overheated state of the electric motor 3.

It is a schematic block diagram of this invention. It is a flowchart which shows a drive control process. It is a control map when rollback is not detected. It is a control map when a rollback is detected. It is a time chart which shows the effect of 1st Embodiment. It is a time chart which shows the effect of 2nd Embodiment. It is a time chart which shows the effect of 3rd Embodiment. It is a time chart which shows the effect of 4th Embodiment.

Explanation of symbols

1FL ・ 1FR Front wheel (Main drive wheel)
1RL, 1RR Rear wheel (auxiliary drive wheel)
2 Engine (Internal combustion engine)
3 Electric motor (electric motor)
4 Automatic transmission 5 Battery 6 Reducer 7 Controller 10 Inhibitor switch 11 Rotation sensor 12 Accelerator sensor

Claims (5)

In a vehicle drive control device capable of driving wheels by an electric motor,
A rollback detecting means for detecting a rollback in which the vehicle moves in the direction opposite to the traveling direction; Drive control means for increasing the driving force ,
The drive control means maintains the driving force in the vehicle traveling direction when the rollback speed decreases if the rollback speed decreases when the driving force in the vehicle traveling direction of the electric motor is increased. A vehicle drive control device.   2. The vehicle drive control device according to claim 1, wherein the main drive wheel is driven by the internal combustion engine and the auxiliary drive wheel can be driven by the electric motor.   The drive control means, when detecting the slip tendency of one of the main drive wheel and the auxiliary drive wheel, increases the other drive force than when not detecting the slip tendency. 3. The vehicle drive control device according to 2.   The vehicle drive control device according to any one of claims 1 to 3, wherein the drive control means increases the drive force of the electric motor in the vehicle traveling direction as the speed of the rollback increases. .   5. The drive control unit according to claim 1, wherein the drive control unit increases the driving force of the electric motor in the vehicle traveling direction as the slope of the road surface with respect to the vehicle traveling direction becomes steeper. 6. Vehicle drive control device.

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