JP6879699B2 - Vehicle driving force control device - Google Patents

Description

The present invention particularly relates to a driving force control device for a vehicle that is installed in an electric vehicle having a plurality of driving devices that can independently control the driving force of the left and right wheels so that they can rotate in opposite directions to control the driving force. It is related to the control when the wheel is locked.

Examples of an electric vehicle having a drive device capable of independently controlling the driving force of the left and right wheels include a vehicle using an in-wheel motor and a vehicle having a plurality of motors mounted on the vehicle body side such as in the hood. In the vehicle given here as an example, the mechanism for generating the driving force includes a motor, a motor and a speed reducer, and a device having a universal joint such as a constant velocity joint. Therefore, these are summarized in this specification. And use it as a drive device. The wheels are connected to the drive device, and the driving force is transmitted from the wheels to the road surface.

When the vehicle is running, for example, by involving a falling object on the road, a wedge-shaped resistance generating portion is generated between the wheel and the wheel house or suspension mechanism covering the wheel, which may cause the wheel to lock. Further, in the vehicle mentioned above, it is conceivable that the wheel lock may be caused by the failure of the drive device. Specifically, this failure may be caused by foreign matter getting caught in the bearing or reduction gear, or damage to the motor. Collectively, in this specification, it is referred to as a lock of the drive device or an abnormality of the drive device.

Japanese Unexamined Patent Publication No. 2006-115636 Japanese Patent No. 5397294 Japanese Patent No. 4877296

When the above-mentioned lock occurs while the vehicle is running, the rotation of the wheels is fixed and a braking force is generated between the wheels and the ground contact surface. In other words, it can be said that the part that caused the lock generates a fixing force (torque) that overcomes this braking force.
The braking force generated by locking one of the left and right drive devices causes the vehicle to make a turning moment. The patent document is aware of the problem of the generation of this turning moment, and also generates a reverse torque (braking torque) in the other driving device that remains, and as a result, locks both wheels so that the turning moment is not generated. It is 1. However, in this method, as pointed out in Patent Document 2, by locking both wheels, a turning moment is not generated, but the operation becomes inoperable.
In Patent Document 3, with respect to the portion corresponding to the driving device defined as described above, the weakest portion is provided in the path for transmitting the driving force (torque) so that the weakest portion is broken by the braking force due to the lock. It is proposed to design it. Further, Patent Document 2 proposes that when a lock is detected in a vehicle having a drive device having such a weakest portion, torque is generated in a motor so as to break the weakest portion.

A structure as shown in Patent Documents 2 and 3 and a control suitable for the structure can obtain desirable results in terms of safety, but it may be a structural weakness or may not include such a structure due to design reasons. To do. Therefore, it is desired to prepare a measure for canceling the locked state in the drive device having no special structure.

Therefore, a suitable measure was examined. It is assumed that in a vehicle having two independent drives, for example, independent drive devices on the left and right sides of the front wheels, one drive device is locked. It is assumed that the loads applied to the left and right wheels at this time are equal. The maximum value of the force that each of the left and right wheels can transmit to the road surface is the product of the load and the coefficient of friction between the wheels and the road surface, and when the wheels are locked and sliding on the road surface, multiply by the coefficient of dynamic friction. , Multiply the maximum coefficient of static friction when the vehicle is stopped or the wheels are rotating. Also, the maximum static friction coefficient is generally larger than the dynamic friction coefficient.

If the vehicle stops after one of the drives is locked, the maximum force that the wheels can transmit to the road surface is the product of the maximum coefficient of static friction between the wheels and the road surface and the load, which is normal. The forces that can be transmitted to the road surface by the operating drive and the locked drive are equal, and they cannot start moving again. Even if the wheel is spun using a drive device that operates normally, the coefficient of dynamic friction is applied between the wheel and the road surface, and even this cannot start moving. In other words, if more than half of the number of drive wheels of the vehicle is locked and stopped, it can be said that the vehicle cannot start moving again in consideration of cases other than two-wheel drive.
From the above, it can be seen that when the place where the vehicle is stopped is a main road or an expressway, it is desirable to release the lock because there is a concern that a following vehicle may collide.

Even if the driving force is exerted by a normal driving device during coasting (wheels are locked and dragging the road surface) so that the vehicle will not stop even if a lock occurs, the wheels will lock. It can be seen that the state of dragging the road surface exerts the maximum value of the braking force that can be transmitted at the time of dynamic friction on the road surface, and the driving force that can be transmitted by the driving device that operates normally is the driving force that can be transmitted at the time of static friction. Even if the maximum value is exhibited, the driving force of the vehicle as a whole is half that of the normal state, and the braking force due to the lock is generated, so the vehicle cannot obtain sufficient acceleration and cruises. It's difficult.

A structure as shown in Patent Documents 2 and 3 and a control suitable for the structure can obtain desirable results in terms of safety, but it may be a structural weakness or may not include such a structure due to design reasons. To do. For this reason, a lock occurs in a drive device that does not have a special structure, and if it cannot be released, the vehicle is likely to stop, and in the stopped state, the lock can be released. There is room for measures.

An object of the present invention is to be installed in an electric vehicle having a drive device capable of independently controlling the driving force of the left and right wheels, and even if the drive device does not have a special structure for unlocking, for example, foreign matter to a wheel house. It is an object of the present invention to provide a vehicle driving force control device that can take measures to release the locked state at an early stage when the vehicle is stopped due to a sudden locked state such as the biting of the vehicle.

The vehicle driving force control device of the present invention is installed in an electric vehicle having a plurality of driving devices 5 and 5 capable of independently controlling the driving forces of the left and right wheels 2 and 2 so as to be able to rotate in opposite directions, and is based on an accelerator command. A vehicle driving force control device that controls the driving devices 5 and 5.
A drive device lock detection unit 13 that monitors whether the drive device 5 is locked when the vehicle is running, and
A stop detection unit 18 that detects whether the vehicle is in a stopped state,
When the stop detection unit 18 detects that the vehicle has stopped after the lock is detected by the drive device lock detection unit 13, torque is applied to the drive device 5 in which the lock is detected in the direction opposite to the traveling direction of the vehicle. , The lock release control unit 16 that outputs to the drive device as a torque command for the purpose of unlocking,
It is characterized by having.

According to this configuration, when lock is detected, lock is detected in either the left or right drive devices 5 and 5, and it is detected that the vehicle has stopped after that, torque is applied to the locked drive device 5 in the direction opposite to the traveling direction. Is output. As a result, a force is generated in the driving device 5 that has been locked due to a cause such as the wedge being struck in a direction of loosening the action of the wedge, and the lock is attempted to be released. Therefore, even if the drive device 5 locks during traveling and then stops, the lock can be released. Further, the lock can be released even if the drive device 5 does not have a special structure for unlocking such as a weak portion for breaking. The lock may be detected by a conventionally used method.

More specifically, it is assumed that the drive device 5 is locked while the vehicle is moving forward. At this time, each drive device 5 outputs torque for forward drive. When the drive device 5 locks in this state, it means that a force due to the cause of the lock acts in a direction that hinders the forward movement. When the torque for driving forward cannot be transmitted, the driving device 5 receives an external force from the road surface. Since the external force from the road surface acts in the direction of turning the wheel 2 in the forward direction, the wedge is made to work deeper, for example, when the wedge is struck by foreign matter biting into the wheel 2. The force will be applied in the direction.
The traveling direction when the lock occurs is obtained from the rotation direction of the wheel 2. Therefore, if the torque is output in the direction opposite to the traveling direction before the stop after the vehicle has stopped without releasing the lock, a force acts in the direction of loosening the wedge. In this state, if the wheel can be rotated to the extent that the wheel spins in the direction opposite to the traveling direction, the cause of the lock may be eliminated.

In the present invention, the lock release control unit 16 includes a lock release torque command unit 14 and a driving force command switching unit 15.
The rotation speed information of the drive devices 5 and 5 is input to the drive device lock detection unit 13 and the lock release torque command unit 14.
The rotation speed information of the drive devices 5 and 5 is input to the drive device lock detection unit 13, the lock release torque command unit 14, and the vehicle stop detection unit 18.
When the drive device lock detection unit 13 detects a lock, the drive device lock detection unit 13 outputs a drive device lock signal to the lock release torque command unit 14.
When the vehicle stop detection unit 18 detects the vehicle stop state, the vehicle stop detection unit 18 outputs a stop signal to the lock release torque command unit 14.
When the stop signal and the drive device lock signal are input, the lock release torque command unit 14 obtains the drive device 5 that has detected the lock from the rotation speed information of the drive device 5 that can normally drive the lock release torque command unit 14. A reverse torque command is generated based on a torque pattern for unlocking that outputs torque in the direction opposite to the traveling direction of the vehicle, and the reverse torque command and the lock release command signal are transmitted to the driving force command switching unit 15. Output to
When the lock release command signal is input, the driving force command switching unit 15 changes the torque command for the driving devices 5 and 5 that has detected the lock to a normal torque command based on the accelerator command. Alternatively, the reverse torque command may be output. The rotation speed information of the drive device 5 may be the rotation speed of the wheel 2 or the rotation speed of the electric motor.

Here, various forms such as lock detection and torque output in the direction opposite to the traveling direction after the vehicle is stopped can be output in a step shape or intermittently in a pulse shape, so that the lock can be released. It was described as the torque pattern of.
By making the reverse torque command a command based on the torque pattern, it is possible to issue a reverse torque command that is likely to cause lock release confirmed by tests, simulations, and the like. Further, the lock release torque command unit 14 generates a reverse torque command and a lock release command signal, and the driving force command switching unit 15 outputs a reverse torque command instead of the normal torque command by these commands. By doing so, appropriate control can be easily performed.

In the case of this configuration, the accelerator command is a command output from the operation detection unit 11a of the accelerator operation means 11 operated by the driver, and the accelerator command is input to the lock release torque command unit 14. As one of the conditions for the lock release torque command unit 14 to output one or both of the reverse torque command and the lock release command signal, the condition of presence / absence of the accelerator command may be included.
Further, a brake command output from the operation detection unit 19a of the brake operation means 19 operated by the driver is input to the lock release torque command unit 14, and the lock release torque command unit 14 is the reverse torque command or the above. As one of the conditions for outputting one or both of the lock release command signals, the condition for the presence / absence of the brake command may be included.

When the lock is released and the wheel 2 rotates as a result of outputting the torque in the traveling direction before stopping as the reverse torque for releasing the lock when the accelerator and brake are not operated and the parking brake is not applied. , The vehicle will start moving without the driver's operation. Therefore, for safety reasons and the driver's operational feeling, it is necessary to include an accelerator command or a brake command operated by the driver as a condition for the lock release torque command unit 14 to output the reverse torque command or the lock release command signal. It is preferable in terms of eliminating the discomfort.

In the present invention, when the drive device lock detection unit 13 detects that the locks of the drive devices 5 and 5 have been released, the lock release torque command unit 14 releases the lock. The reverse torque command is set to zero so as not to output the torque pattern for this purpose, or the lock release command signal is changed and output so that the driving force command switching unit 15 outputs the torque command at the normal time. Either or both may be implemented.
By setting the reverse torque command to zero, the vehicle can rotate freely and is driven by one wheel, but it can run more safely so that it will not be locked again. When the driving force command switching unit 15 outputs the torque command at the normal time, the normal running can be started as soon as possible after the lock is released.

In the case of this configuration, the lock release torque command unit 14 issues a reverse torque command if the predetermined conditions are satisfied even if the drive device lock detection unit 13 does not detect that the lock has been released. You may set it to zero.
If reverse torque is applied for a long time without unlocking, it will lead to excessive temperature rise of the drive device 5, so it is safe to set the reverse torque command to zero when the specified conditions are met. preferable.

In the case of this configuration, as a result of satisfying the predetermined conditions, after the reverse torque command is set to zero, the lock release torque command unit 14 monitors the output of the drive device lock detection unit 13. If the lock is released, the lock release command signal may be changed so that the driving force command switching unit 15 outputs a torque command at the normal time.
This is because the lock was already released as a result of the torque output in the reverse direction, but the drive device 5 was not rotating as a result of the torque command in the reverse direction and the torque for rotating the wheel 2 being antagonized by the road surface. It may be that the drive device 5 starts to rotate by stopping the torque output. As before, if it rotates by a predetermined amount, it is judged that it has rotated, and it is judged that the lock has been released successfully.

The predetermined condition may be a certain time after the lock release control unit 16 outputs a torque pattern for lock release as a reverse torque command.
If the reverse torque is applied for a long time, the drive device 5 may overheat, so the reverse torque is released. However, if an abnormality is determined based on the result obtained by the temperature sensor 17, it is already acceptable. It may be over temperature and it makes more sense to make time-based decisions.

The predetermined condition is even if the temperature information obtained by the temperature sensor 17 installed in the drive device 5 exceeds a threshold value set so as not to cause burning due to overheating. good.
The problem caused by applying the reverse torque for a long time is due to overheating. Therefore, by eliminating the application of the reverse torque when the temperature of the drive device 5 exceeds the set threshold value, the burnout due to overheating occurs. Is prevented. In this case, it is preferable that the temperature sensor 17 can perform rapid measurement.

In the present invention, while the lock release control unit 16 outputs the torque in the opposite direction to the drive device 5 as the torque command, the vehicle traveling direction in which the torque is generated in the direction opposite to the traveling direction before the stop is determined. The reverse torque command guiding means 25 for prompting the driver by outputting the output to the display / sound generating device 26 provided in the vehicle may be provided.
For example, if the reverse torque command guiding means 25 is locked during forward movement, the guidance in the traveling direction of the vehicle to be guided is set to reverse. The driver operates the accelerator in response to this guidance, outputs torque in the direction opposite to the direction of travel up to that point by the accelerator command, and tries to move the vehicle backward by the normal drive device 5, so that the wheel 2 The force that turns the drive device 5 in the backward direction can be transmitted from the vehicle, and a larger force can be applied to the portion that causes the lock.
The display / sound generator 26 may be a device that visually notifies, such as a meter panel in front of the driver's seat, or a device that notifies by sound such as an alarm sound or voice.

The vehicle driving force control device of the present invention is equipped in an electric vehicle having a plurality of driving devices capable of independently controlling the driving forces of the left and right wheels so that they can rotate in opposite directions, and controls the driving device based on an accelerator command. A drive device lock detection unit that monitors whether or not the drive device is locked when the vehicle is running, and a stop detection unit that detects whether or not the vehicle is in a stopped state. When the stop detection unit detects that the vehicle has stopped after the lock is detected by the drive device lock detection unit, the lock is released from the drive device in which the lock is detected in the direction opposite to the traveling direction of the vehicle. Since it has a lock release control unit that outputs to the drive device as a torque command for the purpose of, even if the drive device does not have a special structure for unlocking, for example, a foreign object is caught in a wheel house. When the vehicle suddenly becomes locked and the vehicle is stopped, measures can be taken to release the locked state at an early stage.

It is a block diagram which shows the conceptual structure of the driving force control device of the vehicle which concerns on one Embodiment of this invention. It is a flow chart of an example of the processing performed by the driving force control device. It is a flow chart of another example of the processing performed by the driving force control device. It is a flow chart of still another example of the processing performed by the driving force control device. It is a graph which shows the relationship between the intermittent torque command and the output torque. It is a graph of an example of a torque pattern. It is a graph of another example of a torque pattern. It is sectional drawing of the example of the drive device which comprises an in-wheel motor drive device. It is the schematic sectional drawing of the example of the on-board type drive device.

An embodiment of the present invention will be described with reference to the drawings. Here, as an example, for the driving force control device 1, two driving devices 5 that can independently control the driving forces of the wheels 2 and 2, which are the two left and right driving wheels, so that they can rotate in opposite directions as shown in FIG. A case where it is applied to a four-wheel electric vehicle having, and 5 will be described. The wheels 2 and 2, which are the two left and right drive wheels, may be front wheels or rear wheels. The drive device 5 includes an on-board type motor installed in the bonnet described with reference to FIG. 9 and a transmission mechanism thereof, even if the drive device 5 is an in-wheel motor drive device described later with reference to FIG. Also good

The drive device 5 is a device that outputs torque to the wheels 2 based on a torque command, and in addition to the electric motor 4 and its drive transmission system, a current drive element for driving the electric motor 4 and an calculation for motor control. It will be described as including the arithmetic unit (motor driver that puts these together) that performs the above. In the illustrated example, the drive device 5 includes an inverter device 9 that serves as the motor driver. The inverter device 9 includes an inverter (not shown) including a bridge circuit including a plurality of current drive elements, and the calculation means.

The driving force control device 1 may be a part of a control device (often referred to as a vehicle integrated control device or the like) that controls a vehicle in an ECU (electric control unit) or the like. The driving force control device 1 reads at least the rotation speed information of the driving device 5 (for example, one or both of the motor rotation speed and the wheel rotation speed) from the driving device 5, and transmits a torque command to the driving device 5. .. In the driving force control device 1, the torque command is basically in response to an accelerator command given from an accelerator operation detection unit 11a that detects an operation amount of the accelerator operation device 11 operated by a driver such as an accelerator pedal. , The main driving force control unit 12 is generated. More specifically, the main driving force control unit 12 receives a brake command of the brake operation detection unit 19a for detecting the operation amount of the brake operation device 19 and a steering amount of the steering handle (not shown) in response to the accelerator command. The torque command may be generated by adding a correction amount such as turning assist control and vehicle attitude stabilization control according to the above. The means for outputting the accelerator command and the brake command may be an automatic driving device (not shown) that controls cruise control, automatic driving, and the like.

As a control means for releasing the lock of the drive device 5 in the drive force control device 1 having the above configuration,
A drive device lock detection unit 13 that monitors whether the drive device 5 is locked when the vehicle is running, a vehicle stop detection unit 18 that detects whether the vehicle is in a stopped state, and the drive device lock detection unit 13. Detects a lock, and when the stop detection unit 18 detects that the vehicle is stopped after this detection, locks the torque in the direction opposite to the traveling direction of the vehicle to the drive device 5 in which the lock is detected. A lock release control unit 16 that outputs a torque command for the purpose of release to the drive device 5 is provided. The lock release control unit 16 includes a lock release torque command unit 14 and a driving force command switching unit 15. Information on the rotation speed of the drive device 5 is input to the drive device lock detection unit 13 and the lock release torque command unit 14.

The drive device lock detection unit 13 monitors the lock of the drive device 5, and outputs a drive device lock signal to the lock release torque command unit 14 when the lock is detected.
The stop detection unit 18 outputs a stop signal to the lock release torque command unit 14 when the stop state is detected.

Hereinafter, the specific configuration of the driving force control device 1 will be described including the operation procedure shown in the flow charts of FIGS. 2 to 4. FIG. 2 shows a basic operation and does not have step S5. 3 and 4 are different from FIG. 2 in that they have determination steps S5 and S5'for FIG. 2, respectively, and are the same as those in FIG. 2 except for the above.
First, the drive device lock detection unit 13 or the lock release torque command unit 14 in the drive force control device 1 determines the traveling direction using the rotation speed read from the drive devices 5 and 5 (step S1). ..

Next, the drive device lock detection unit 13 performs lock detection (step S2). This lock detection may be performed by a conventionally used method. This is, for example, a detection method for determining a lock when the difference in the rotation speeds of the left and right drive devices 5 and 5 exceeds a preset allowable value. Here, it is assumed that the lock is detected and the drive device lock detection unit 13 transmits the drive device lock signal to the lock release torque command unit 14. This lock detection process is always performed, and the drive device lock signal is withdrawn as soon as the lock is released.
The vehicle stop detection unit 18 determines whether the vehicle is stopped based on the rotation speeds of the drive devices 5 and 5 (step S3). This determination may be made together with the rotation speed of the driven wheel (not shown) and acceleration information. When a stop is detected, a stop signal is output to the lock release torque command unit 14.

When the lock release torque command unit 14 receives the drive device lock signal and the stop signal, the lock release torque command unit 14 issues a reverse torque command in the direction opposite to the traveling direction based on the traveling direction determined earlier, according to the torque pattern for unlocking. It is transmitted to the driving force command switching unit 15. That is, the lock release torque pattern is output (step S6). At the same time as this transmission, the lock release torque command unit 14 transmits the lock release command signal to the driving force command switching unit 15. Further, as will be described in detail later, a brake command and an accelerator command may be input to the lock release torque command unit 14 in order to determine the reverse torque command.

The driving force command switching unit 15 outputs a torque command that is not intended to release the lock, such as a torque command output from the main driving force control unit 12 in response to the accelerator command, and a torque command that is output from the lock release torque command unit 14. It has the role of switching between the torque command for the purpose of unlocking. As a result of the processing up to this point, the driving force command switching unit 15 switches the torque command of the locked drive device 5 so as to output a reverse torque command based on the lock release command signal.

As a result of the drive device 5 outputting torque in the reverse direction in accordance with the reverse torque command, it is assumed that the lock is released and the drive device 5 starts rotating in the direction opposite to the traveling direction (step S7, yes). The lock release torque command unit 14 detects the rotation and determines whether or not the lock has been released. Here, as a threshold value for whether or not the lock is released, it is determined that the wheel 2 has rotated, for example, if the wheel 2 rotates 1/16 from the position of the wheel 2 when the vehicle is stopped.

On the other hand, it is assumed that the lock is not released even if the drive device 5 outputs the torque in the reverse direction according to the reverse torque command (step S7, no). In that case, the lock release torque command unit 14 outputs a lock release command signal, investigates the elapsed time from the start of outputting the lock release torque pattern to the drive device 5 (step S8), and sets in advance. Determine whether or not the set amount of time has passed. This is mainly a measure to prevent the motor coil of the electric motor 4 of the drive device 5 from being burnt out due to overheating, or the current driving element (FET, IGBT, etc.) that controls the current of the electric motor 4 is not burnt out. .. If the electric motor 4 is rotating, the motor coil and the current drive element rotate while switching, so even if the amount of current does not burn out, the electric motor is fixed and the phase does not switch. Since there is a high possibility that the product will burn out when an electric current is applied, such a process is performed.

When the preset time has elapsed, the lock release torque command unit 14 stops the reverse torque output for unlocking (step S9), and sets the reverse torque command to zero.
Here, the lock release torque command unit 14 again determines whether or not the lock has been released from the rotation speed (rotation amount) of the drive device 5 (step S10). This is because the lock was already released as a result of the torque output in the reverse direction, but the drive device 5 was not rotating as a result of the torque command in the reverse direction and the torque for rotating the wheel 2 being antagonized by the road surface. It may be that the drive device 5 starts to rotate by stopping the torque output. As before, if the rotation is performed by a predetermined amount, it is determined that the rotation has been performed, and it is determined that the lock has been released successfully (step S11). If it does not rotate by a predetermined amount, it is determined that the release of the lock has failed (step S12).
However, since the vehicle is stopped, the drive device 5 does not rotate, and there is a high possibility that it is determined that the drive device 5 remains locked. Therefore, when the vehicle speed is zero, a special determination is made, and the process is terminated without determining whether or not the lock is released.
When the lock release is successful in the above process, the lock release command signal is stopped, and a torque command from the main driving force control unit 12 based on the command of the accelerator operating means 11a such as the accelerator pedal is output to the drive device 5. To do so.

Even if the lock is released up to this point, the lock release command signal may be maintained and the reverse torque command may be left at zero. As a result, once the lock of the drive device 5 is detected, the torque is not output from the drive device 5. This is because if debris or the like that causes locking is present in the drive device 5, particularly in the speed reducer, it is expected that biting may occur again when the drive torque is exerted again. In addition, as a result of outputting the torque in the opposite direction to release the lock, the temperature of the motor coil and the current drive element is expected to rise. Therefore, in order to prevent burning, there is also a purpose of not exerting the drive torque in order to lower the temperature. ..

The determination of the end of output of the reverse torque for releasing the lock will be described.
For example, in a state where neither the accelerator operating means 11 nor the brake operating means 19 is operated and the parking brake is not applied, the reverse torque for releasing the lock is the traveling direction (assuming that the vehicle is moving forward) before stopping. As a result of outputting the torque in the opposite direction (reverse direction), when the lock is released and the wheel 2 rotates, the vehicle starts to move (reverse) without the driver's operation. Here, as shown above, it is set that the lock is released, for example, when the wheel 2 rotates 1/16, and if the wheel 2 rotates that much, the torque output is prohibited until the vehicle stops again. Then, the distance that the vehicle travels while outputting torque can be shortened. Although it depends on the size of the wheel 2, in the case of a small automobile, the moving distance when the wheel 2 rotates 1/16 is generally about 100 to 200 mm.

The output of the reverse torque for releasing the lock according to the brake command and the accelerator command will be described.
As shown above, if the reverse torque for unlocking is output in the non-operation state, the vehicle may move. Shortening the amount of rotation required to determine that the lock is released enhances safety, but is not preferable when, for example, a worker is nearby to investigate a failure.

With this problem in mind, the lock release command unit 14 must be in a state where, for example, a brake operating means 19 such as a brake pedal is depressed (step S5 in FIG. 3) and a braking force is generated (brake on). For example, the reverse torque for releasing the lock may not be output (step S5, no). At this time, for example, when a mechanism capable of independently adjusting the braking force of each of the wheels 2 and 2, the locked drive device 5 (and the wheel 2 connected thereto) does not generate a braking force and the other wheels. 2 exerts a braking force, the locked drive device 5 outputs a torque for unlocking, and if the lock is released and the torque output is large, the wheel spin is started to determine whether the lock is released. It will be easier to do.

Similarly, the lock release command unit 14 determines, for example, whether the accelerator command is on or off (step S5'in FIG. 4), and outputs a reverse torque for unlocking only when there is an accelerator command. You can do it. It is assumed that the accelerator command here is a signal with a positive and negative sign, and indicates an accelerator command as a forward / backward command. The driver is instructing the intention of torque output in the direction of travel instructed by the forward / backward instruction such as the shift lever and the accelerator command. When the drive device 5 is stopped in the locked state, as shown above, due to the balance of the forces that the wheels 2 can transmit to the road surface, it is not possible to move forward or backward when the drive device 5 is locked. Therefore, the traveling direction before the vehicle is stopped is instructed, and when the accelerator is depressed, the locked drive device 5 outputs the torque in the opposite direction to the traveling direction before the vehicle is stopped to be the torque output for releasing the lock. Here, even if the lock is released, the force in the traveling direction output by the normal drive device 5 and the force in the opposite direction by the drive device 5 from which the lock is released are balanced, and it is safe without starting to move.

In addition to these, the lock release command unit 14 may output the reverse torque for unlocking only when there is either the brake command or the accelerator command.

Further, while the lock release control unit 16 outputs the torque in the opposite direction to the drive device 5 as the torque command, guidance in the vehicle traveling direction for generating torque in the direction opposite to the traveling direction before stopping is provided. The reverse torque command guiding means 25 that urges the driver by outputting the output to the display / sound generator 26 provided in the vehicle may be provided. As a result, the lock can be released more reliably. For example, if the reverse torque command guiding means 25 is locked during forward movement, the guidance in the traveling direction of the vehicle to be guided is set to reverse. The driver operates the accelerator in response to this guidance, outputs torque in the direction opposite to the direction of travel up to that point by the accelerator command, and tries to move the vehicle backward by the normal drive device 5, so that the wheel 2 The force that turns the drive device 5 in the backward direction can be transmitted from the vehicle, and a larger force can be applied to the portion that causes the lock.
The display / sound generator 26 may be, for example, a device that visually notifies the liquid crystal screen of the meter panel or display lamps, or a device that notifies by sound such as voice or buzzer sound.

A specific example of the torque pattern for releasing the lock will be described.
As the torque pattern for unlocking, for example, a form in which the maximum torque that can be output by the drive device 5 is output in a stepwise manner in the opposite direction can be adopted. As a result, the maximum force is applied in the direction of loosening the wedge with respect to the wedge-shaped foreign matter biting that is suspected to be the cause of the lock. However, as described above, as a result of passing a large current for outputting a large torque in a state where the phase is fixed, there is a risk of overheating and burning. Therefore, the output time is determined by the configuration of the power supply voltage, the type of the driving element, the cooling method, etc., but is generally considered to be about 10 seconds. However, before the torque in the opposite direction is output as a result of the temperature rise during normal driving before the occurrence of the abnormality and the attempt to drive in the traveling direction between the time when the lock is actually locked and the time when the lock is detected. Since it is expected that the heat is already generated, it may be necessary to shorten the time further to avoid burning.

As a form other than the step-like output, a form in which torque opposite to the traveling direction is intermittently output in a pulse shape can be adopted (see FIG. 5). This is because the peak of the magnitude of the output torque is the same as the previous step-like torque output, but since heat is not generated during intermittent operation, the amount of heat generated can be easily regarded as equivalent to outputting the time-averaged torque. The temperature rise is slower than the stepped output, reducing the possibility of overheating and burning. At this time, it is preferable that the time for outputting the reverse torque is longer than the time from the command until the torque reaches the target value and becomes a steady state with reference to the response speed of the torque of the drive device 5. The specific length of this time is about 100 ms, although it is necessary to consider a delay in calculation in the motor driver for driving the motor in the drive device 5. Further, the intermittent time should be equal to or longer than the time for outputting the reverse torque with reference to the cooling performance of each part. In addition, in order to avoid burning when heat is already generated, refer to the temperature of each part before outputting the pulsed reverse torque, for example, the temperature of the motor coil and the temperature of the current drive element, and the on / off time near the upper limit value. The ratio may be such that the on-time is shortened or zero, and the lower the temperature is, the longer the on-time is for the on-off time ratio, the shorter the off-time, and the larger the time average of the torque. Here, the on-time and the off-time can be set independently, and the total is undefined, so the duty ratio is not set. However, the total of the on-time and the off-time is fixed, and the duty ratio is changed according to the temperature described above. May be good.

Further, for example, even when the phase is fixed by the lock, the output torque obtained from the amount of current that does not immediately cause overheating or burning may be output in the direction opposite to the traveling direction. The torque pattern may be set according to the accelerator command as described above. For example, when it is desired to output torque to the locked drive device 5 in the backward direction, the normal drive device 5 outputs torque to the locked drive device 5 in the forward direction in response to the driver's accelerator command in the forward direction. Outputs torque in the backward direction. If the torque is output as it is according to the accelerator command, there is a possibility of burning as described above. Therefore, by adopting the torque pattern as shown in FIG. 5, it is possible to prevent the torque from retreating unexpectedly and to prevent burning.

At this time, torque output is started in response to the driver's accelerator on, but the normal drive device 5 intermittently outputs torque in the forward direction, and the locked drive device 5 intermittently outputs torque in the backward direction. Output. As a result, even if the lock is released, it will not retreat unexpectedly. After repeating several times, both can move forward if the lock is released by outputting torque in the forward direction. In order to avoid burning, the torque output is stopped after a certain period of time. During the above operation, the driver is stepping on the accelerator as a manifestation of intention to move forward. Therefore, even if the lock is released and the vehicle moves forward, it is relatively safe because the event is within the expected range.
In this embodiment, the timing at which the normal drive device 5 outputs the intermittent torque in the forward direction and the timing at which the locked drive device 5 outputs the intermittent torque in the backward direction are simultaneous. However, the timing at which the normal drive device 5 outputs the intermittent torque in the forward direction and the timing at which the locked drive device 5 outputs the intermittent torque in the backward direction may be different. That is, the timing at which the normal drive device 5 outputs the intermittent torque in the forward direction and the timing at which the locked drive device 5 outputs the intermittent torque in the backward direction may alternate.

Further, as described above, when the display / sound generating means 26 urges the driver to generate the torque in the direction opposite to the traveling direction up to that point and releases the lock, FIGS. A torque pattern such as 7 may be used. To urge the driver is to notify the occurrence of an abnormality (lock) by using the display on the meter panel, which is the display / sound generating means 26, an alarm sound, a voice, etc., and reverse the direction of travel for the purpose of resolving the abnormality (lock). It is to inform the driver to change the direction of travel of the vehicle (mostly the shift lever position) in the direction. For example, when the vehicle is locked while traveling in the forward direction and the vehicle is stopped as it is, the shift lever is urged to be changed to the reverse position in order to release the lock. It is assumed that the driver accordingly commands the accelerator as a retreat. Also at this time, torque is output intermittently in order to avoid burning. After repeating the process several times, it is investigated whether the lock is released and the wheel 2 can rotate and retreat. Here, for example, if it can be determined that the wheel 2 is rotating based on the idea that it is better not to retreat as it is from the viewpoint of safety confirmation of the surroundings because the retreat starts if the lock is released. The torque output may be stopped.

The determination to stop the output of the torque pattern for unlocking will be described.
Up to this point, the output of the torque pattern for unlocking has been determined to continue or end based on time, but even if it is determined based on the temperature of the motor coil, drive element, cooling water or lubricating oil. good. The reason for making the judgment based on the time so far is that it is highly possible that the above-mentioned temperature information obtained by the sensors does not correctly reflect the actual temperature. The reason is shown below.

The sensor for measuring the temperature described above measures the temperature of the normally rotating drive device 5, and the response speed of the sensor is also optimized for it, and the temperature of the object to be measured is the highest. In many cases, the threshold value for determining an abnormality is determined so that the difference between the portion and the temperature obtained by the sensor is also within an acceptable range. On the other hand, when locked, it is conceivable that the temperature rises rapidly and locally as described above. From the above, when the abnormality is judged based on the result obtained by the above sensor, it is possible that the temperature has already exceeded the permissible temperature, and it is judged that it is rational to make the judgment based on the time. It is the result of
With this problem in mind, select a sensor that responds quickly, design the drive device 5 so that the sensor output reflects the local temperature rise, and then unlock the lock. The output of the torque pattern for this purpose may be determined to be continued or terminated based on the temperature information obtained by the temperature sensor.

Up to this point, it has been described that the reverse torque command is set to zero when the lock release is successful or unsuccessful, but the lock release command signal may be continued without ending the output. This is a measure to prevent torque output in order to prevent recurrence even if the lock release described above is successful, or even if the lock release fails, it burns out. This is because it is for avoidance such as.
When switching the torque output direction as described above, create a pattern in advance that does not cause a failure such as burning, and when the output of that pattern is completed, the torque pattern for unlocking is released. You may decide to stop the output of. This is synonymous with time-based judgment.

FIG. 8 shows an example in which the drive device 5 is an in-wheel motor drive device. The drive device 5 has an electric motor 4, a speed reducer 6, and a wheel bearing 7, and a part or the whole thereof is arranged in the wheel 2. The rotation of the electric motor 4 is transmitted to the wheels 2 via the speed reducer 6 and the wheel bearings 7. The drive device 5 generates a drive torque or a braking torque by switching the direction of the rotation of the electric motor 4. A brake rotor 8a constituting the friction braking device 8 is fixed to the flange portion of the hub wheel 7a of the wheel bearing 7, and the brake rotor 8a rotates integrally with the wheel 2. The electric motor 4 is, for example, an embedded magnet type synchronous motor in which a permanent magnet is built in the core portion of the rotor 4a. The electric motor 4 is a motor provided with a radial gap between the stator 4b fixed to the housing 4c and the rotor 4a attached to the rotary output shaft 9.

FIG. 9 shows an example in which the drive device 5 is an onboard type. The output shaft of the motor 4A with a speed reducer composed of the electric motor 4 and the speed reducer 6 is connected to the rotating side wheel of the wheel bearing 24 via the drive shaft 21 and the universal joints 22 and 23 at both ends thereof. There is. The wheel bearing 24 is a rolling bearing that supports the wheel 2. The motor 4A with a speed reducer is installed on a chassis (not shown). The drive device 5 is composed of the motor 4A with a speed reducer, the drive shaft 21, the universal joints 22 and 23, and the wheel bearing 24.

Although the embodiments for carrying out the present invention have been described above based on the embodiments, the embodiments disclosed this time are exemplary in all respects and are not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 ... Driving force control device 2 ... Wheel 4 ... Electric motor 5 ... Driving device 11 ... Accelerator steering means 11a ... Operation detection unit 13 ... Drive device lock detection unit 14 ... Lock release torque command unit 15 ... Driving force command switching unit 16 ... Lock release control unit 18 ... Stop detection unit 19 ... Brake operation means 19a ... Operation detection unit 25 ... Reverse torque command guidance means 26 ... Display / sound generation means

Claims (10)

It is a vehicle driving force control device that is installed in an electric vehicle having a plurality of driving devices that can independently control the driving force of the left and right wheels so that they can rotate in opposite directions, and controls the driving device based on an accelerator command.
A drive device lock detector that monitors whether the drive device is locked when the vehicle is running,
A stop detection unit that detects whether the vehicle is in a stopped state,
When the stop detecting unit after the lock has been detected by said driving device lock detecting unit detects that it has stopped, lock on is detected the drive device, progress direction opposite to the direction of the torque just before stop of the vehicle Is output to the drive device as a torque command for the purpose of unlocking.
A vehicle driving force control device characterized by having. In the vehicle driving force control device according to claim 1, the lock release control unit includes a lock release torque command unit and a drive force command switching unit.
Before hear operated device lock detecting unit, the lock eliminate torque command unit and stop detection unit, the rotational speed information of the drive device is input,
When the drive device lock detection unit detects a lock, the drive device lock detection unit outputs a drive device lock signal to the lock release torque command unit.
When the vehicle stop detection unit detects the vehicle stop state, the vehicle stop detection unit outputs a stop signal to the lock release torque command unit.
When the stop signal and the drive device lock signal are input, the lock release torque command unit obtains from the rotation speed information of the drive device that can normally drive the drive device that has detected the lock. A reverse torque command based on a torque pattern for unlocking that outputs torque in the direction opposite to the traveling direction is generated, and the reverse torque command and the lock release command signal are output to the driving force command switching unit.
When the lock release command signal is input, the driving force command switching unit receives the torque command for the driving device that has detected the lock, instead of the normal torque command based on the accelerator command. A vehicle driving force control device that outputs a reverse torque command. In the vehicle driving force control device according to claim 2, the accelerator command is a command output from an operation detection unit of an accelerator operating means operated by the driver, and the accelerator command is a lock release torque command unit. The driving force control device of the vehicle including the condition of presence / absence of the accelerator command as one of the conditions for the lock release torque command unit to output one or both of the reverse torque command and the lock release command signal. .. In the vehicle driving force control device according to claim 2, a brake command output from an operation detection unit of a brake operating means operated by the driver is input to the lock release torque command unit, and the lock release torque command unit is used. However, as one of the conditions for outputting one or both of the reverse torque command and the lock release command signal, the vehicle driving force control device includes the condition of presence / absence of the brake command. In the vehicle driving force control device according to claim 2, when the lock release torque command unit detects that the drive device lock has been released, the lock release torque command unit causes the lock release torque command unit. The reverse torque command is set to zero so as not to output the torque pattern for unlocking, or the lock release command signal is changed so that the driving force command switching unit outputs the torque command at the normal time. A vehicle driving force control device that implements either output. In the vehicle driving force control device according to claim 5, the lock release torque command unit satisfies a predetermined condition even if the drive device lock detection unit does not detect that the lock has been released. A vehicle driving force control device that, if satisfied, sets the reverse torque command to zero. In the vehicle driving force control device according to claim 6, after the reverse torque command is set to zero as a result of satisfying the predetermined conditions, the lock release torque command unit is the drive device lock detection unit. A vehicle driving force control device that monitors the output and changes the lock release command signal so that the driving force command switching unit outputs a torque command at the normal time if the lock is released. In the vehicle driving force control device according to claim 6 or 7, the predetermined condition is that after the lock release control unit outputs a torque pattern for lock release as a reverse torque command. A vehicle driving force control device after a certain period of time has passed. In the vehicle driving force control device according to claim 6 or 7, the predetermined condition is that the temperature information obtained by the temperature sensor mounted in the driving device causes burning due to overheating. A vehicle driving force control device, which is a condition that the threshold value is exceeded. In the driving force control device for a vehicle according to any one of claims 1 to 9, while the lock release control unit outputs the torque in the opposite direction as the torque command to the driving device. Driving force of a vehicle having a reverse torque command prompting means for urging the driver by outputting the vehicle traveling direction for generating torque in the direction opposite to the traveling direction before stopping to the display / sound generator provided in the vehicle. Control device.

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