JP4956775B2 - Steering control device - Google Patents

Description

  The present invention relates to a steer-by-wire system in which a steering unit having a steering handle and a steering reaction force actuator, and a steering unit having a steering wheel and a steering actuator can be mechanically separated and connected via a backup cable. It belongs to the technical field of steering control devices.

In a so-called steer-by-wire (hereinafter abbreviated as “SBW”) system in which the steering wheel and the steering wheel are not mechanically connected, if an abnormality is recognized in a part of the system, the backup clutch is promptly By connecting the steering wheel and the steered wheel mechanically, the steered wheel can be steered by the driver's steering force (see, for example, Patent Document 1).
JP 2001-106111 A

  However, in the conventional steering control device, when the generator is stopped due to engine stop or the like during execution of SBW control, current is consumed without the battery being charged. There may be a problem during starting.

The present invention has been made paying attention to the above problems, and an object thereof is to provide a steering control device capable of suppressing a decrease in battery voltage when the engine is stopped.

In order to achieve the above object, in the present invention,
A steering part having a steering handle and a steering reaction force actuator, and a steering part having a steering wheel and a steering actuator can be mechanically separated and connected via backup means,
The steering reaction force actuator and the steering actuator are driven by power supply from the battery,
Steer-by-wire control is performed by turning the steering unit and the steered unit, and turning the steering control to make a turning angle according to the steering state, and the steering reaction force control giving the steering reaction force according to the turning state. In a steering control device having a steering control means for performing,
Before Symbol steering control means, when the engine is stopped, and connecting the steering unit and the steering unit through the backup unit, after connected to the steering actuator and the steering reaction force actuator than before connecting The power to be supplied is suppressed .

Thus, steering In the control device, when the engine is stopped, it is steering unit and is mechanically connected to the steering unit through the backup unit, the steering reaction force after coupling than before coupling of the present invention Reduce the power supplied to the actuator and the steering actuator. As a result, a decrease in battery voltage when the engine is stopped can be suppressed.

  Hereinafter, the best mode for carrying out the steering control device of the present invention will be described based on Examples 1 to 3 shown in the drawings.

First, the configuration will be described.
FIG. 1 is an overall configuration perspective view showing an SBW system to which the steering control device of the first embodiment is applied.

  As shown in FIG. 1, the SBW system to which the steering control device of the first embodiment is applied includes a steering handle 1, a torque sensor 2, a steering angle sensor 3, a reaction force motor rotation angle sensor 4, and a reaction force motor. (Steering reaction force actuator) 5, backup clutch 6, backup cable 7, first turning motor rotation angle sensor 8, first turning motor (steering actuator) 9, and second turning motor rotation angle Sensor 10, second turning motor (steering actuator) 11, turning angle sensor 12, communication line 13, reaction force control device 14, first turning control device 15, and second turning control. A device 16, a steering mechanism 17, and left and right front wheels (steering wheels) 18a and 18b are provided.

  In the SBW system of the first embodiment, the steering unit having the steering handle 1 and the reaction force motor 5, and the steering unit having the left and right front wheels 18a and 18b and the steering motors 9 and 11 are backup means (backup clutch 6, backup unit). It can be mechanically separated and connected via a cable 7). When mechanically separating the steering part and the steered part, the backup clutch 6 is opened, and when the steering part and the steered part are mechanically coupled, the backup clutch 6 is connected (fastened).

  Then, the steering unit and the turning unit are separated by releasing the backup clutch 6, and the turning control by the turning control devices 15 and 16 with the turning angle according to the steering state, and the steering reaction force according to the turning state. Steer-by-wire control (hereinafter abbreviated as SBW control) is performed by the steering reaction force control by the reaction force control device 14 that applies the above.

  The steering control at the time of SBW control is, for example, from the deviation between the command turning angle multiplied by the gear ratio set according to the steering angle and the vehicle speed and the actual turning angle detected by the turning angle sensor 12. It is converted into steering torque and a limiter process is performed to obtain a motor control command value. Then, by turning servo control by feedforward control + feedback control + robust compensation, the command current is obtained from the motor control command value, and the turning motors 9 and 11 are driven.

  For the reaction force control during SBW control, for example, the steering reaction force torque corresponding to the steering state of the left and right front wheels 18a, 18b is set by a value obtained by multiplying the actual steering angle detected by the steering angle sensor 3 by the steering reaction force gain. Then, a limiter process is performed to obtain a motor control command value. Then, the reaction force servo control by feedforward control + feedback control + robust compensation is used to obtain the command current from the motor control command value, and the reaction force motor 5 is driven.

  Further, the reaction force control device 14 is connected to the steering unit and the steering unit via the backup cable 6 by connecting the backup clutch 6 according to the status of the SBW system, such as SBW system activation, SBW system termination, or SBW system abnormality. And When the backup clutch 6 is connected, the reaction force control device 14 and the steering control devices 15 and 16 perform “EPS control” (= steering assist control) using at least one of the reaction force motor 5 and the steering motors 9 and 11 as assist means. )I do.

FIG. 2 is a connection diagram of the SBW system according to the first embodiment and the power source, engine, and the like of the vehicle.
The key operation for the driver to start / stop the engine is read from the ignition key switch 19 through the ignition relay 20 to the reaction force and steering control devices 14, 15, 16 as an ignition key switch (IGN_SW) signal. Therefore, each control device 14, 15, 16 can recognize the state of the ignition key switch 19. Further, the rotation state of the engine 21 is measured by an engine control unit (ECU) 22, and the information is sent to each of the steering and reaction force control units 14, 15, and 16 via the communication line 13.

  The turning and reaction force control devices 14, 15, and 16 are supplied from the battery 23 as a power source for driving the control device itself, and the power source for driving the turning motors 9 and 11 and the reaction force motor 5. The left and right front wheels (steering wheels) 18a and 18b are steered for the vehicle to travel by receiving power supply. The battery 23 is charged by a generator (alternator or the like) 25 driven by engine driving. The battery 23 also supplies power for driving the engine for running the vehicle.

Next, the operation will be described.
[Steering control processing]
FIG. 3 is a flowchart showing the flow of the steering control process of the first embodiment, and each step will be described below (corresponding to the steering control means).

In step S1, it is determined whether or not the engine is stopped from the engine speed or the like (corresponding to chargeability determination means). If YES, the process proceeds to step S2, and if NO, the process proceeds to step S5.

  In step S2, it is determined from the detected value of the steering angle sensor 3 whether or not the steering handle 1 is in the neutral position. If YES, the process proceeds to step S3. If NO, the process proceeds to step S4.

  In step S3, it is determined whether or not the engine has been stopped for a predetermined time or more. If YES, the process proceeds to step S6. If NO, the process proceeds to step S4. Here, the predetermined time from the engine stop is not a fixed time set in advance, but may be variable according to, for example, the battery S.O.C (battery charge state) or current consumption. For example, when the amount of charge is large and the amount of current consumption is small, the time may be long, and when the amount of charge is small and the amount of current consumption is large, the time may be short.

  In step S4, the backup clutch 6 is connected, and the process proceeds to step S7.

  In step S5, the backup clutch 6 is released and the process proceeds to step S8.

  In step S6, SBW control is continued and the process proceeds to return.

  In step S7, the control is switched to EPS control and the process proceeds to return.

  In step S8, switching to SBW control is performed, and the process proceeds to return.

[Steering control operation]
If the steering wheel 1 is in the neutral position when the engine is stopped, the process proceeds from step S1 to step S2 to step S4 to step S7 in the flowchart of FIG. 3. In step S4, the backup clutch 6 is connected, and in step S7 Transition to EPS control.

  When the steering wheel 1 is being steered when the engine is stopped (not in the neutral position), the flow proceeds from step S1 to step S2 to step S3 to step S6 until a predetermined time elapses after the engine is stopped in step S3. Is repeated and SBW control is continued. Thereafter, when a predetermined time has elapsed since the engine stopped, the process proceeds from step S3 to step S4 to step S7, and after the backup clutch 6 is connected, the process proceeds to EPS control.

  When the engine is restarted, the process proceeds from step S1 to step S5 to step S8. In step S5, the backup clutch 6 is connected, and in step S8, the process proceeds to SBW control.

[Battery voltage drop when the engine is stopped]
In an SBW system that uses an electric motor to steer an automobile, the steering handle side and the steering mechanism are normally mechanically separated from each other. This SBW system is known to have a mechanical backup mechanism (for example, a backup clutch) that mechanically connects the steering handle and the steering actuator in the event of a system failure so that steering can be performed in the same manner as a normal steering system. ing.

  Originally, the backup mechanism is an auxiliary steering means in the event of a system malfunction, but in addition to that, for example, as disclosed in Japanese Patent Application Laid-Open No. 2001-106111, when the conditions for engine stop and vehicle stop are satisfied, the backup clutch To connect the steering wheel and the steering wheel while the system is stopped.

  By the way, in an automobile or the like equipped with a manual transmission, the engine may stop (engine stall) due to an erroneous clutch operation of the transmission without turning off the ignition key switch. The engine stop in this case is not intended by the driver, and it is assumed that the engine stops while the driver is steering. In the steering system, even if there is no safety problem when the vehicle is stopped, there is a demand for avoiding sudden changes in the steering force during steering as much as possible due to the product characteristics. Avoid sudden changes in the steering force even when the engine is stopped. I want.

  If the SBW system is stopped immediately when the engine is stopped and the backup clutch is connected regardless of the ignition key switch state, the steering reaction force suddenly increases as shown in FIG. turn into.

  FIG. 5 (a) is a time chart showing engine speed, battery voltage, vehicle speed, ECU state, control state of SBW control, and connection / release state of the backup clutch from ignition key ON to ignition key OFF. FIG. 5B shows the engine speed, the control state of the SBW control, the connection / disconnection of the backup clutch when the backup clutch is connected while the engine is stopped, that is, from the time Ta to the time Tb of FIG. It is a time chart which shows the state of an open state, a steering angle, a steering gear ratio, and N deviation.

  As shown in FIG. 5 (b), during the variable gear ratio control in the SBW system, that is, the “steering gear ratio” before “engine stop” (time point t1) in FIG. 5 (a), If the gear ratio is not 1 and the rotation angle of the steering wheel does not match that of the steering wheel, and the SBW system is stopped and the backup clutch is connected at time t2 when the engine is stopped, the "engine stop" There is a possibility that N deviation occurs as in “N deviation amount”. In this case, when the driver starts the engine again, for example, N deviation correction processing described in Japanese Patent Application Laid-Open No. 2004-99011 must be performed, and software processing becomes complicated.

  In particular, when the driver is steering greatly, the amount of N deviation increases, and the N deviation correction processing takes time (time t3 to time Tb). In addition, since the N deviation occurs in the first place, a difference occurs in the steering angle and the traveling direction of the vehicle, and the steering wheel is in a state of being cut off even though the steering wheel is in the neutral position. There is a risk of discomfort.

  Although there is a method of continuing the SBW control even when the engine is stopped, in this case, in the SBW system operated by electricity, the generator for charging the battery is stopped when the engine is stopped, and after time t1 in FIG. As is clear from the “battery charging current” and “consumption current” in FIG. 1, the battery is not charged and only the current is consumed. When the capacity of the battery is limited and a system with a large current (for example, 100A) flowing at the time of steering, such as SBW, is operating when the engine is stopped, the remaining battery level will eventually run out. There is a risk that the battery voltage will drop and it will be difficult to restart the engine (after time t2, the battery voltage is below 8V, which allows the engine to start reliably).

[Operation of connecting the backup clutch when the generator is stopped]
On the other hand, in Example 1, when the generator 25 stops, the backup clutch 6 is connected and the SBW control is stopped, so that a decrease in battery voltage can be suppressed. Further, since the backup clutch 6 is connected, the steering by the steering handle 1 is possible. Furthermore, when the ignition key switch is turned off, the side brake is turned on, the door lock is locked, and the like, and the SBW system termination condition is satisfied after the backup clutch 6 is connected, the SBW control can be promptly terminated.

[Transition from SBW control to EPS control]
Further, in the first embodiment, when the backup clutch 6 is connected, the SBW control is switched to the electric power steering (EPS) control that assists the steering torque with respect to the driver's steering. As shown in FIG. 7, when the engine is stopped, the generator 25 is also stopped (time t1), and the “battery charging current” is also 0 A (time t2). When the driver steers and continues the SBW control in this state, the current consumption is large as indicated by the broken line of “current consumption”, and only the discharge of the battery 23 proceeds. As shown by the broken line of “battery voltage”, the battery voltage is also increased. descend.

  On the other hand, in the first embodiment, when the engine is stopped at time t1, the backup clutch 6 is connected and switched to EPS control, so that the current consumption is suppressed as compared to the normal SBW control as indicated by the solid line of “current consumption”. can do. This is because the SBW control performs all the steering with the electric motors (steering motors 9 and 11), and further causes the driver to generate the steering reaction force with the electric motor (reaction force motor 5), which requires a lot of current. In contrast, EPS control is based on the steering force of a person (driver) and assists the steering torque with an electric motor, so power consumption can be reduced (for example, about 1/3). ). In other words, in contrast to the steering torque in the SBW control, in the EPS control, the assist torque is added to the driver's steering torque and the steering torque is applied to the left and right front wheels 18a, 18b. Only torque (= steering torque−steering torque) needs to be output, and as a result, less current is consumed.

  Also, compared to the case where the SBW system is stopped when the engine is stopped and the backup clutch is connected, the steering assist torque is output by EPS control and the steering reaction force does not increase, so the driver is steering when the engine is stopped. Even if it does, sudden change of steering force does not occur, which is preferable in terms of merchantability.

[Continuation of SBW control immediately after engine stop]
In the first embodiment, when the engine 21 is stopped and is not restarted for a predetermined time or longer, the backup clutch 6 is connected to switch to EPS control.

  For example, if the engine stops due to an erroneous operation of the transmission clutch, this is an unintended engine stop for the driver, and in most cases, the driver will restart the engine immediately. The time is very short.

  On the other hand, in the first embodiment, it is possible to prevent the occurrence of N deviation by continuing the SBW control without shifting to the EPS control until a predetermined time elapses after the engine is stopped. This is because, as shown in FIG. 8B, the engine stop time is shorter than the predetermined time, so that the connection of the backup clutch 6 and the switching to the EPS control are not performed. 6 is left free.

Also, while the driver is steering, connect the backup clutch and switch control from SBW control to EPS control, or release the backup clutch at the next engine restart and control from EPS control to SBW control. When the operation of switching is performed, the steering torque fluctuates slightly. However, by shifting from the SBW control to the EPS control after a lapse of a predetermined time from the engine stop, the fluctuation of the steering torque can be suppressed. This variation in steering torque is unique to the mechanical backup type SBW, which is not found in conventional steering systems, and there is no problem in safety, but it is not preferable in terms of merchantability and should be avoided as much as possible.
If the engine stop time is short, the discharge amount of the battery 23 is small and the burden on the battery 23 is small.

[EPS control transition action after neutralization of steering wheel]
Furthermore, in Example 1, when the position of the steering wheel 1 becomes neutral after the engine is stopped, the backup clutch 6 is connected to switch to EPS control.

  When the engine is stopped during traveling, since the vehicle is traveling, self-aligning torque is generated in a direction to return the steering wheel to the neutral position. The steering handle is also affected by this force, and the force acts in a direction to return to the neutral position. Therefore, if the steering wheel 1 is in the neutral position, the left and right front wheels 18a and 18b are also in the neutral position. Therefore, by connecting the backup clutch 6 in this state, occurrence of N deviation can be prevented.

  If the backup clutch 6 is connected by switching to the EPS control at this timing in the engine stop state, no N shift occurs, so even if the subsequent EPS control is performed, the steering wheel 1 and the left and right front wheels 18a and 18b are shifted to the angular positions. Therefore, it is possible to eliminate the uncomfortable feeling that the steering wheel 1 is slightly cut even though the vehicle is traveling straight ahead. Further, when the engine is restarted next time, it is not necessary to perform the N deviation correction process, and the process can be simplified.

  Further, since the steering reaction force is small when the steering wheel 1 is in the neutral position, the fluctuation of the steering torque when the backup clutch 6 is connected and switched to the EPS control can be made relatively small, which is preferable in terms of merchantability.

Next, the effect will be described.
In the steering control device of the first embodiment, the effects listed below can be obtained.

  (1) The steering part having the steering handle 1 and the reaction force actuator 5, and the steering part having the left and right front wheels 18a and 18b and the steering actuators 9 and 11 are connected via backup means (backup clutch 6, backup cable 7). Steering control that is mechanically separable and connectable, separates the steering part and the turning part, and makes a turning angle according to the steering state, and applies a steering reaction force according to the turning state. In a steering control device having a steering control means for performing steer-by-wire control by force control, chargeability determination means (step S1) for determining whether or not the battery 23 relating to traveling of the vehicle can be charged. The provided steering control means connects the steering part and the steered part via the backup means when the battery 23 cannot be charged. Therefore, it is possible to suppress a decrease in battery voltage when the generator 25 is stopped.

  (2) Since the steering control means performs EPS control using at least one of the reaction force actuator 5 and the turning actuators 9 and 11 as an assist means after connecting the steering part and the turning part, the steering force of the driver is reduced. By switching to the base EPS control, power consumption can be reduced compared to the SBW in which the left and right front wheels 18a, 18b are steered by the steered motors 9, 11.

  (3) The steering control means connects the steering part and the steered part when the unchargeable state continues for a predetermined time, so that the backup means cannot be connected in a short time, and N deviation occurs. As well as steering torque fluctuations when shifting to SBW control.

  (4) When the steering handle 1 is in the neutral position, the steering control means connects the steering portion and the steered portion. Therefore, when the steering handle 1 and the left and right wheels 18a, 18b are both in the neutral position, the backup clutch 6 By connecting N, occurrence of N deviation can be reliably prevented.

  In the second embodiment, when the engine is stopped, the gear ratio, which is the ratio of the steering angle of the steering handle 1 to the steering angle of the left and right front wheels 18a, 18b, is returned to the mechanical gear ratio. This is an example of connection. In addition, since it is the same as the structure of Example 1 shown in FIG.1 and FIG.2 in a structure, illustration and description are abbreviate | omitted.

Next, the operation will be described.
[Steering control processing]
FIG. 9 is a flowchart showing the flow of the steering control process according to the second embodiment. Each step will be described below. In addition, the same step number is attached | subjected to the step which performs the process same as Example 1 shown in FIG. 3, and description is abbreviate | omitted.

  In step S11, it is determined whether or not the gear ratio is 1. If YES, the process proceeds to step S4. If NO, the process proceeds to step S12.

  In step S12, the gear ratio is brought close to 1 by a predetermined amount by variable gear ratio control, and the process proceeds to step S3.

[Steering control operation]
When the steering wheel 1 is steered when the engine is stopped, in the flowchart of FIG. 9, the process proceeds from step S1 to step S2 to step S11. In step S11, when the gear ratio is 1, step S11 to step S4. → The flow proceeds to step S7, and after the backup clutch 6 is connected, the control shifts to EPS control.

  If the gear ratio is other than 1 in step S11, step S1 is repeated until it is determined in step S11 that the gear ratio is 1 or until it is determined in step S3 that a predetermined time has elapsed since the engine was stopped. Step S2 → Step S11 → Step S12 → Step S3 → Step S6 is repeated, and in step S12, SBW control for gradually bringing the gear ratio closer to 1 is continued.

[Gear ratio variable action]
In the second embodiment, when the variable gear ratio control or the like is performed by the SBW control and the rotation angle of the steering side does not coincide with the rotation angle of the steering handle 1, the gear ratio is gradually set to 1 after the engine is stopped. When the gear ratio becomes 1, the backup clutch 6 is connected and the control is switched to EPS control.

  If the steering gear ratio converges to 1 as shown in “steering gear ratio” at the time of “engine stop” in FIG. 10A (time t1 in FIG. 10B), the angle of the steering wheel 1 and the steering The rotation angles on the same side coincide with each other, and even when the backup clutch 6 is connected and the control is switched to the EPS control, no N deviation occurs.

  In other words, in the first embodiment, when the steering wheel 1 is in the neutral position, switching to EPS control avoids the occurrence of N shift, but by further actively performing the process of returning the steering gear ratio to 1, Even if the steering wheel 1 is in a position other than neutral, it is possible to switch to EPS control without causing N deviation.

Next, the effect will be described.
In the steering control device of the second embodiment, the effects listed below can be obtained in addition to the effects (1) to (4) of the first embodiment.

  (5) The steering control means returns the gear ratio, which is the ratio of the steering angle of the steering handle 1 to the steering angle of the left and right front wheels 18a, 18b, to the mechanical gear ratio (= 1), and then turns the steering unit and the steering unit. Therefore, the occurrence of N deviation when the backup clutch 6 is connected can be more effectively prevented.

  The third embodiment is an example in which the steering reaction force in the steering reaction force control is made larger than that in the normal SBW control when shifting from SBW control when the engine is stopped to EPS control. In addition, since it is the same as the structure of Example 1 shown in FIG.1 and FIG.2 in a structure, illustration and description are abbreviate | omitted.

Next, the operation will be described.
[Steering control processing]
FIG. 11 is a flowchart showing the flow of the steering control process according to the third embodiment. Each step will be described below. In addition, the same step number is attached | subjected to the step which performs the same process as Example 2 shown in FIG. 9, and description is abbreviate | omitted.

  In step S21, it is determined whether the vehicle is stopped based on the vehicle speed or the like. If YES, the process proceeds to step S22, and if NO, the process proceeds to step S24.

  In step S22, it is determined whether or not the steering reaction force gain is 5 or more. If YES, the process proceeds to step S2, and if NO, the process proceeds to step S23.

  In step S23, the steering reaction force gain is brought close to 5 by a fixed amount, and the process proceeds to step S23.

  In step S24, it is determined whether or not the steering reaction force gain is greater than one. If YES, the process proceeds to step S25, and if NO, the process proceeds to step S2.

  In step S25, the steering reaction force gain is brought close to 1 by a fixed amount, and the process proceeds to step S2.

  In step S26, it is determined whether or not the steering reaction force gain is greater than one. If YES, the process proceeds to step S27, and if NO, the process proceeds to step S5.

  In step S27, the steering reaction force gain is brought close to 1 by a fixed amount, and the process proceeds to step S5.

[Steering control operation]
If the vehicle is stopped when the engine is stopped, the process proceeds from step S1 to step S21 to step S22 in the flowchart of FIG. 11. If the steering reaction force gain is smaller than 5 in step S22, step S22 → The process proceeds from step S23 to step S2 (hereinafter omitted). In step S23, steering reaction force control is performed while gradually increasing the steering reaction force gain.

  If the vehicle is running when the engine is stopped, the process proceeds from step S1 to step S21 to step S24. If the steering reaction force gain is greater than 1 in step S24, step S25 to step S2 (hereinafter omitted). In step S25, steering reaction force control is performed while gradually decreasing the steering reaction force gain.

  When the vehicle restarts after stopping, the process proceeds from step S1 to step S26. If the steering reaction force gain is greater than 1 in step S26, the process proceeds from step S27 to step S5. As shown in “steering reaction force gain” from time t1 to time t2), the steering reaction force control is performed while the steering reaction force gain is gradually reduced.

[Steering reaction force increasing action]
In the third embodiment, when the vehicle is stopped in the SBW control until the backup clutch 6 is connected when the engine is stopped and the control is switched to the EPS control, the steering reaction force is gradually made heavier than that in the normal SBW control. . Further, when the vehicle starts traveling while the steering reaction force is increased, the steering reaction force is returned to the normal weight. Furthermore, the steering assist current when switching to the EPS control is also reduced, and the steering reaction force that is made heavy by the SBW control is reduced to prevent sudden changes in the steering reaction force.

  When the engine is stopped, the generator is also stopped, so we want to reduce current consumption as much as possible for the purpose of battery protection. However, since the steering reaction force is light in the normal SBW control, the driver can steer fast with a small steering force as shown by the broken line of “steering angle” after time t1 in FIG. 13 (b). Since the steering control device operates the steered wheels according to the driver's steering, if a large and fast steering is performed, the steering motor will also flow a large amount of current accordingly, and a large amount of current will be consumed. The

  Here, as in the third embodiment, by performing SBW control in which the steering reaction force is heavier than usual, the steering reaction force is increased due to the heavy steering reaction force as indicated by the solid line with respect to the broken line of “steering angle” after time t1. The steering amount of the person is small and slow, and the steering amount on the steered side is also small and slow. As a result, less current is required for the steering motors 9 and 11. In order to increase the steering reaction force, a large current is required for the reaction force motor 5, but since the steered motors 9 and 11 consume more power than the reaction force motor 5, the steering reaction force is larger. Suppressing the steering amount by increasing the force reduces the current consumption of the SBW system as a whole.

  Note that when the vehicle is stopped, there is no safety impact even if the steering reaction force increases, so there is no problem even if the current consumption is limited for the purpose of battery protection. The heavier situation is equivalent to the conventional hydraulic power steering and does not give the driver a sense of incongruity.

  Further, since the steering reaction force is changed by controlling the current of the reaction force motor 5, it is easy to increase the weight gradually, and the steering force does not change suddenly. Further, since the steering reaction force is returned to the normal weight when the vehicle starts to travel, there is no difficulty in steering during traveling, and there is no problem in traveling safety.

Next, the effect will be described.
In the steering control device of the third embodiment, in addition to the effects (1) to (4) of the first embodiment and the effect (5) of the second embodiment, the following effects can be obtained.

  (6) When it is determined that charging is impossible, the steering control means increases the steering reaction force, so by increasing the driver's steering, the turning amount on the steering side is small and slow. As a result, the current consumption of the steered motors 9 and 11 can be reduced to suppress battery consumption.

(Other examples)
As described above, the best mode for carrying out the steering control device of the present invention has been described based on the first to third embodiments. However, the specific configuration is not limited to these embodiments. Design changes and additions are permitted without departing from the spirit of the invention according to each of the claims.

  For example, in the first to third embodiments, the example of the steering control device applied to the steer-by-wire system using the backup cable and the backup cable clutch as the backup means is shown. However, the steering unit and the steered unit are mechanically coupled. Any system having backup means that can be applied can be applied to steer-by-wire systems other than the first to third embodiments.

1 is an overall configuration perspective view showing an SBW system to which a steering control device of Embodiment 1 is applied. It is a connection diagram with the SBW system of Example 1, and the power supply of a vehicle, an engine, etc. 3 is a flowchart illustrating a flow of steering control processing according to the first embodiment. It is a steering angle-steering torque characteristic diagram when the backup clutch is connected immediately after the engine is stopped. It is a time chart at the time of connecting a backup clutch during an engine stop. It is a time chart when SBW control is continued while the engine is stopped. 6 is a time chart when SBW control and EPS control are performed while the engine of the first embodiment is stopped. 6 is a time chart when the SBW control is continued for a predetermined time from the engine stop according to the first embodiment. 7 is a flowchart illustrating a flow of steering control processing according to the second embodiment. It is a time chart at the time of performing the process which returns a gear ratio to 1 before connecting a backup clutch by the engine stop of Example 2. FIG. 12 is a flowchart illustrating a flow of steering control processing according to the third embodiment. 6 is a time chart when the vehicle travels with the engine stopped according to the first embodiment. 6 is a time chart when the reaction force gain is increased by SBW control during the connection of the backup clutch from the engine stop according to the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering handle 2 Torque sensor 3 Steering angle sensor 4 Reaction force motor rotation angle sensor 5 Reaction force motor (steering reaction force actuator)
6 Backup clutch 7 Backup cable 8 First turning motor rotation angle sensor 9 First turning motor (steering actuator)
10 Second turning motor rotation angle sensor 11 Second turning motor (steering actuator)
DESCRIPTION OF SYMBOLS 12 Steering angle sensor 13 Communication line 14 Reaction force control apparatus 15 1st steering control apparatus 16 2nd steering control apparatus 17 Steering mechanism 18a, 18b Left and right front wheel (steering wheel)
19 Ignition Key Switch 20 Ignition Relay 21 Engine 22 Engine Control Device 23 Battery 24 Power Supply Line 25 Generator

Claims (7)

A steering part having a steering handle and a steering reaction force actuator, and a steering part having a steering wheel and a steering actuator can be mechanically separated and connected via backup means,
The steering reaction force actuator and the steering actuator are driven by power supply from the battery,
Steer-by-wire control is performed by turning the steering unit and the steered unit, and turning the steering control to make a turning angle according to the steering state, and the steering reaction force control giving the steering reaction force according to the turning state. In a steering control device having a steering control means for performing,
Before Symbol steering control means, when the engine is stopped, and connecting the steering unit and the steering unit through the backup unit, after connected to the steering actuator and the steering reaction force actuator than before connecting A steering control device that suppresses power to be supplied . The steering control device according to claim 1, wherein
The steering control unit performs steering assist control using at least one of the steering reaction force actuator and the steering actuator as an assisting unit after connecting the steering unit and the steering unit. . In the steering control device according to claim 1 or 2,
The steering control device is characterized in that the steering control unit connects the steering unit and the steered unit when an unchargeable state continues for a predetermined time. The steering control device according to any one of claims 1 to 3,
The steering control device, wherein the steering control unit connects the steering unit and the steered unit when the steering handle is in a neutral position. In the steering control device according to any one of claims 1 to 4,
The steering control means returns the gear ratio, which is the ratio of the steering angle of the steering wheel to the steering angle of the steered wheel, to a mechanical gear ratio, and then connects the steering unit and the steering unit. A steering control device characterized by that. The steering control device according to any one of claims 1 to 5,
The steering control means, when in an impossible state of charge, after increasing the steering reaction force, and characteristics that you connecting the steering unit and the steering unit via said backup means A steering control device. A steering unit having a steering handle and a steering reaction force actuator, and a steering unit having a steering wheel and a steering actuator can be mechanically separated and connected via backup means, and by supplying power from a battery In the steering control device in which the steering reaction force actuator and the steering actuator are driven ,
When the engine is stopped, through a pre-Symbol backup means to connecting the steering unit and the steering unit, connecting after suppressing the power supplied to the steering actuator and the steering reaction force actuator than before connecting A steering control device characterized by:

Images