JP4062207B2 - Vehicle steering system - Google Patents

Description

  The present invention relates to an improvement in a fail-safe function in a vehicle steering system employing a so-called steer-by-wire system.

  In a steering apparatus that employs a steer-by-wire system, the steering member driven by the operation of the operation member is not mechanically connected to the wheel so that the steering angle changes on the wheel. Communicating.

In a steering device that employs a steer-by-wire system, the operation member and the wheel are not mechanically connected, and therefore a fail-safe function is required to prevent the steering motor from becoming unsteerable when the steering motor is abnormal. Therefore, it is considered that a spare steering motor is provided and the steering angle is changed by the spare steering motor when the steering motor is abnormal (see Patent Document 1).
JP 2000-53015 A

  Even if a spare steering motor is provided as described above, if the battery for supplying power to the spare steering motor is exhausted, the fail-safe function cannot be achieved when the steering motor is abnormal.

  In addition, when an on-vehicle power generation device such as an alternator breaks down while the vehicle is running, it is necessary to maintain a steering function for guiding the vehicle traveling by inertia to a safe stop location such as a road shoulder. . However, if the battery is rapidly exhausted due to a failure of the power generation device, the steering function cannot be maintained even if the steering motor is normal.

  The above problem is promoted when not only a steering motor but also a large load such as an air conditioner is connected to the battery. The present invention aims to solve the above problems.

  The present invention relates to a steering motor, a preliminary steering motor, and the movement of the steering motor and the preliminary steering motor so that the steering angle can be changed without mechanically connecting an operating member to the wheel. A mechanism capable of transmitting; a first battery for supplying power to the steering motor; a second battery for supplying power to the preliminary steering motor; and driving the steering motor in response to an operation of the operating member. The present invention is applied to a vehicle steering apparatus including a control system.

One feature of the present invention is that an abnormality detecting means for the steering motor, an engine stop detecting means for detecting whether or not the vehicle running engine is stopped during vehicle running, and a degree of consumption of the first battery are set. A battery consumption detecting means for detecting whether or not the steering wheel is detected, and a steering angle sensor for detecting a steering angle as a steering amount of the wheel, and when the abnormality is detected in the steering motor, the spare motor is replaced with the spare motor. A steering motor is driven by the control system in response to an operation of the operation member, and the preliminary steering steering is used instead of the steering motor when the engine is stopped while the vehicle is running and when the consumption of the first battery or more is detected. The motor is driven by the control system in accordance with the operation of the operation member, and the battery consumption detecting means is detected by the steering angle sensor from the output time point of the drive signal of the steering motor. Monitoring the response time until the change time of the corner, in that for detecting the setting more consumption of the first battery if it exceeds the set time of the response time is predetermined.
Thus, the fail-safe function can be reliably achieved by driving the preliminary steering motor by supplying power from the second battery when the steering motor is abnormal.
In this case, the control system drives the steering motor so as to eliminate a deviation between a target rudder angle corresponding to the operation of the operation member and a rudder angle detected by the rudder angle sensor, and the abnormality detection unit Preferably, the deviation between the target rudder angle and the detected rudder angle is monitored, and if the deviation is equal to or greater than a set value over a set time, an abnormality of the steering motor is preferably detected.

Another feature of the present invention is that means for detecting whether or not the vehicle running engine has stopped during vehicle running, means for detecting whether or not the consumption level of the first battery is greater than or equal to a set value , A steering angle sensor for detecting a steering angle as a steering amount of the wheel, and the preliminary steering motor instead of the steering motor when detecting engine stop during running of the vehicle and consumption exceeding the setting of the first battery Is driven by the control system in response to the operation of the operation member, and the means for detecting whether or not the consumption level of the first battery is equal to or greater than a setting is determined by the steering angle from the output time point of the drive signal of the steering motor. The response time until the change of the detected steering angle by the sensor is monitored, and if the response time exceeds a predetermined set time, the consumption of the first battery or more is detected .
As a result, when the engine stops due to a failure of an on-vehicle power generator such as an alternator while the vehicle is running, the steering motor is supplied with power from the first battery until the consumption level of the first battery exceeds a set level. When the consumption level of the first battery is equal to or higher than the set value, the preliminary steering motor supplied with power from the second battery is driven, so that the steering function can be maintained for a long time.

In the present invention, the nominal voltage of the first battery is larger than that of the second battery, and the load including the steering motor connected to the first battery is the preliminary steering connected to the second battery. The load is preferably larger than the load including the motor for use.
Thereby, the driving time of the preliminary steering motor by the second battery can be extended by connecting a large load such as an air conditioner other than the steering motor to the first battery.

  According to the present invention, in a vehicle steering apparatus that employs a steer-by-wire system that changes a steering angle by a steering motor, it is possible to prevent steering from being disabled due to battery consumption when a steering motor or an in-vehicle power generation device fails, A fail-safe function can be surely achieved.

  The vehicle steering apparatus according to the embodiment of the present invention shown in FIG. 1 mechanically connects the operation member 1 to the front left and right wheels 4 with respect to the movement of the steering motor 2 driven in accordance with the rotation operation of the operation member 1. Without being transmitted, the steering gear mechanism 3 transmits to both wheels 4 so that the steering angle changes. As a result, a so-called steer-by-wire system is configured, and the ratio between the operation amount of the operation member 1 and the turning amount of the wheel 4 is variable.

  The operating member 1 is connected to a rotating shaft 10 that is rotatably supported by the vehicle body side. An operation motor 19 that generates an operation torque is connected to the rotary shaft 10. As the operation motor 19, for example, a known direct current brushless motor or the like can be adopted. In this embodiment, the output shaft of the operation motor 19 is integrated with the rotary shaft 10.

  As the steering motor 2, for example, a known DC brushless motor can be employed. As shown in FIG. 2, the steering motor 2 of the present embodiment includes a stator 2 a that is fixed in a housing 5 that is attached to a vehicle body, and a rotor 2 b that is rotatably supported by the housing 5 via a bearing.

  The steering gear mechanism 3 has a steering rod 3a and a ball nut 3c screwed to a ball screw 3b integrated with the steering rod 3a via a ball. The steering rod 3a is inserted into the rotor 2b of the steering motor 2, and the ball nut 3c is connected to the rotor 2b so as to rotate along with the rotor 2b. As a result, the steering motor 2 is driven so that the steering rod 3a moves in the vehicle width direction. Moving. When the movement of the steering rod 3a is transmitted to the wheel 4 through the tie rod 8 and the knuckle arm 9, the turning angle of the wheel 4 changes. In the state where the steering motor 2 is not driven, the wheel alignment is set so that the front left and right wheels 4 can be returned to the straight position by the self-aligning torque.

  The steering gear mechanism 3 transmits the movement of the preliminary steering motor 30 to the wheel 4 so that a change in the steering angle occurs without mechanically connecting the operating member 1 to the wheel 4. That is, a rack 3d is integrally formed on the steering rod 3a, a rotating shaft 3f that rotates together with a pinion 3e meshing with the rack 3d is supported by the housing 5 via a bearing, and preliminary rotation is performed on the rotating shaft 3f via a reduction gear mechanism 3g. The rotation of the motor 30 is transmitted. Accordingly, the steering rod 3a moves in the vehicle width direction by driving the preliminary steering motor 30.

  An angle sensor 11 that detects an operation angle δh from the neutral position as an operation amount of the operation member 1 is provided. A steering angle sensor 13 that detects a steering angle δ as a steering amount of the wheel 4 is provided. In the present embodiment, a movement amount of the steering rod 3a corresponding to the steering amount of the wheel 4 is detected as the steering angle δ. A speed sensor 14 for detecting the vehicle speed V is provided. A torque sensor 44 that detects torque transmitted by the rotary shaft 10 as the operation torque Th of the operation member 1 is provided. The angle sensor 11, the rudder angle sensor 13, the speed sensor 14, and the torque sensor 44 are connected to the control device 20.

The control device 20 constitutes a control system that drives the steering motor 2 via the drive circuit 22 in accordance with the operation of the operation member 1. A power supply first battery 51 is connected to the steering motor 2 via the drive circuit 22. For example, the control device 20 stores a predetermined relationship among the operation angle δh of the operation member 1, the vehicle speed V, and the target rudder angle δ ^*, and eliminates the deviation between the target rudder angle δ ^* and the detected rudder angle δ. Thus, a drive signal for the steering motor 2 is output via the drive circuit 22. Electric power corresponding to the drive signal is supplied from the first battery 51 to the steering motor 2. The relationship between the operation angle δh, the vehicle speed V, and the target rudder angle δ ^* is, for example, that the target rudder angle δ ^* is proportional to the operation angle δh, and that the proportionality constant is a function of the vehicle speed V and the vehicle speed V is large. The target rudder angle δ ^* is set so as to decrease. The method for controlling the steering motor 2 is not particularly limited as long as it can be controlled so that the steering angle δ changes according to the operation of the operation member 1.

The control device 20 controls the operation motor 19 via the drive circuit 23. A power supply first battery 51 is connected to the operation motor 19 via the drive circuit 23. For example, the control device 20 stores a predetermined relationship among the operation angle δh of the operation member 1, the vehicle speed V, and the target operation torque Th ^*, and eliminates the deviation between the target operation torque Th ^* and the detected operation torque Th. As described above, the drive signal of the operation motor 19 is output via the drive circuit 23. Electric power corresponding to the drive signal is supplied from the first battery 51 to the operating motor 19. The relationship among the operation angle δh, the vehicle speed V, and the target operation torque Th ^* is, for example, that the target operation torque Th ^* increases as the operation angle δh increases and the vehicle speed V decreases. Thereby, the operation torque in the direction of returning the operation member 1 to the neutral position acts on the operation member 1, and the operation reaction force can be applied to the driver. The control method of the operation motor 19 is not limited to the method according to the operation angle and the vehicle speed, and for example, a detection sensor such as a yaw rate or a lateral acceleration of the vehicle is provided, and an operation torque according to the detected value is applied. The operating motor 19 may be controlled.

An abnormality detection means for the steering motor 2 is provided. The abnormality detection means of the present embodiment is configured by the control device 20 and monitors the deviation between the target steering angle δ ^* and the detected steering angle δ, and if the deviation is equal to or greater than a set value over a set time, the steering motor 2 An anomaly detection signal is generated. The configuration of the abnormality detection means is not particularly limited as long as it can detect an abnormality of the steering motor 2.

  Engine stop detection means is provided for detecting whether or not the vehicle driving engine has stopped during vehicle driving. The engine stop detection means of the present embodiment includes a current sensor 15 that detects whether or not ignition power is supplied to the engine ignition device, and a control device 20. When the vehicle speed V is not zero and the engine ignition power is not supplied due to a failure of the in-vehicle power generation device or the like, the control device 20 generates an engine stop detection signal. The configuration of the engine stop detection means is not particularly limited as long as it can detect whether or not the engine has stopped while the vehicle is running.

Battery consumption detecting means is provided for detecting whether or not the consumption level of the first battery 51 is greater than or equal to the setting. The battery consumption detecting means of the present embodiment monitors the response time from the output time of the drive signal of the steering motor 2 to the change time of the detected steering angle δ, and if the response time exceeds a predetermined set time, the battery is consumed. It is comprised by the control apparatus 20 which produces | generates a signal .

When the abnormality of the steering motor 2 is detected, the control device 20 drives the preliminary steering motor 30 via the drive circuit 24 according to the operation of the operation member 1 instead of the steering motor 2. In addition, the control device 20 drives the preliminary steering motor 30 in place of the steering motor 2 in accordance with the operation of the operation member 1 when the engine is stopped while the vehicle is running and the consumption of the first battery 51 or more is detected. 24 via the drive. A power supply second battery 52 is connected to the preliminary steering motor 30 via the drive circuit 24. For example, the control device 20 stores a predetermined relationship among the operation angle δh of the operation member 1, the vehicle speed V, and the target steering angle δ ^*, and eliminates the deviation between the target steering angle δ ^* and the detected steering angle δ. Thus, the drive signal of the preliminary steering motor 30 is output via the drive circuit 24. Electric power corresponding to the drive signal is supplied from the second battery 52 to the preliminary steering motor 30. The control method of the preliminary steering motor 30 may be the same as or different from the control method of the steering motor 2.

  The nominal voltage of the first battery 51 is larger than that of the second battery 52. For example, the nominal voltage of the first battery 51 is 42V, and the nominal voltage of the second battery 52 is 12V. The load including the steering motor 2 connected to the first battery 51 is larger than the load including the preliminary steering motor 30 connected to the second battery 52. For example, a relatively large load such as an air conditioner is connected to the first battery 51 in addition to the steering motor 2, and a relatively small load such as a lamp is connected to the second battery 52 other than the preliminary steering motor 30. Is done. As a result, when the first battery 51 and the second battery 52 are not charged due to a failure of the in-vehicle power generation device or the like, the driveable time of the preliminary steering motor 30 by the second battery 52 depends on the first battery 51. It is longer than the driveable time of the steering motor 2.

The flowchart shown in FIG. 3 shows a control procedure of the steering motor 2, the preliminary steering motor 30 and the operation motor 19 by the control device 20. First, the detection value from each sensor is read (step S1), and it is determined whether or not the switching flag is on (step S2). If the switching flag is not on in step S2, the steering motor 2 is supplied from the first battery 51 via the drive circuit 22 so as to eliminate the deviation between the target steering angle δ ^* and the detected steering angle δ as described above. (Step S3), the operation motor 19 is driven via the drive circuit 23 so as to eliminate the deviation between the target operation torque Th ^* and the detected operation torque Th (step S4), and abnormality determination processing is performed. (Step S5), it is determined whether or not the control maintenance flag is ON (Step S6). If the control maintenance flag is on in step S6, the process returns to step S1, and if the control maintenance flag is off, it is determined whether or not to end the control, for example, based on whether or not the ignition switch is off (step S7). If not, the process returns to step S1, and if finished, the switching flag is turned off (step S8), the control maintenance flag is turned off (step S9), and the process is finished. If the switching flag is ON in step S2, the preliminary steering motor 30 is supplied from the second battery 52 via the drive circuit 24 so as to eliminate the deviation between the target steering angle δ ^* and the detected steering angle δ as described above. Driven by the generated electric power (step S10), the process proceeds to step S4.

  FIG. 4 shows the abnormality determination processing procedure in step S5. First, it is determined whether or not the steering motor is abnormal (step S101). If abnormal, the switching flag is turned on (step S102), and the process returns. If the steering motor is not abnormal in step S101, it is determined whether or not the vehicle is traveling (step S103). If the vehicle is not traveling, the process returns. If the vehicle is traveling, the engine stop state is determined. Judgment is made based on the presence or absence of a detection signal (step S104). If the engine is not stopped, the process returns. Next, it is determined whether or not the consumption level of the first battery 51 is greater than or equal to the setting based on the presence or absence of the battery consumption signal (step S106). If not, the process returns. If it is exhausted, the switching flag is turned on ( Step S107) and return.

  According to the above embodiment, the fail-safe function can be reliably achieved by driving the preliminary steering motor 30 by the power supply from the second battery 52 when the steering motor 2 is abnormal. Further, when the engine is stopped due to a failure of an on-vehicle power generation device such as an alternator while the vehicle is running, the steering is supplied with power from the first battery 51 until the consumption level of the first battery 51 exceeds a set level. When the motor 2 is driven and the consumption level of the first battery 51 becomes equal to or higher than the set value, the preliminary steering motor 30 supplied with power from the second battery 52 is driven, so that the steering function can be maintained for a long time. Further, by connecting a large load such as an air conditioner to the first battery 51, the drive time of the preliminary steering motor 30 by the second battery 52 can be extended.

  The present invention is not limited to the above embodiment. For example, only the preliminary steering motor may be connected to the second battery, and the driving time of the preliminary steering motor by the second battery may be made as long as possible. Further, the structure of the mechanism that transmits the movement of the steering motor and the preliminary steering motor to the wheels so that the steering angle changes without mechanically connecting the operation member to the wheels is not particularly limited. A pair of pinions that mesh with the rack formed on the rack may be provided, with one pinion attached to the output shaft of the steering motor and the other pinion attached to the output shaft of the preliminary steering motor.

Structure explanatory drawing of the steering apparatus for vehicles of embodiment of this invention Explanatory drawing of a partial configuration of a vehicle steering system according to an embodiment of the present invention. 6 is a flowchart showing a control procedure of a steering motor, a preliminary steering motor, and an operation motor in the vehicle steering apparatus according to the embodiment of the present invention. The flowchart which shows the abnormality determination process sequence in the steering device for vehicles of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Operation member 2 Steering motor 3 Steering gear mechanism 4 Wheel 11 Angle sensor 13 Steering angle sensor 14 Speed sensor 15 Current sensor 20 Control device 30 Preliminary steering motor 51 First battery 52 Second battery

Claims (4)

A steering motor;
A preliminary steering motor;
A mechanism capable of transmitting movements of the steering motor and the preliminary steering motor to the wheels such that a steering angle change occurs without mechanically connecting an operation member to the wheels;
A first battery for supplying power to the steering motor;
A second battery for supplying power to the preliminary steering motor;
A control system for driving the steering motor in response to an operation of the operation member;
An abnormality detection means of the steering motor ;
Engine stop detection means for detecting whether or not the vehicle driving engine has stopped during vehicle driving;
Battery consumption detecting means for detecting whether or not the consumption level of the first battery is greater than or equal to a setting;
A steering angle sensor for detecting a steering angle as a steering amount of the wheel ,
When the abnormality of the steering motor is detected, the preliminary steering motor is driven by the control system according to the operation of the operation member instead of the steering motor ,
When the engine is stopped while the vehicle is running and the consumption of the first battery or more is detected, the preliminary steering motor is driven by the control system in response to the operation of the operation member instead of the steering motor.
The battery consumption detecting means monitors the response time from the output time of the drive signal of the steering motor to the change time of the detected steering angle by the steering angle sensor, and if the response time exceeds a predetermined set time, A steering apparatus for a vehicle, characterized by detecting consumption exceeding a setting of a first battery . The control system drives the steering motor so as to eliminate a deviation between a target rudder angle according to an operation of the operation member and a rudder angle detected by the rudder angle sensor,
2. The abnormality detection unit according to claim 1, wherein the abnormality detection unit monitors a deviation between the target rudder angle and the detected rudder angle, and detects an abnormality of the steering motor if the deviation is equal to or greater than a set value over a set time . Vehicle steering system. A steering motor;
A preliminary steering motor;
A mechanism capable of transmitting movements of the steering motor and the preliminary steering motor to the wheels such that a steering angle change occurs without mechanically connecting an operation member to the wheels;
A first battery for supplying power to the steering motor;
A second battery for supplying power to the preliminary steering motor;
A control system for driving the steering motor in response to an operation of the operation member;
Means for detecting whether or not the vehicle running engine has stopped during vehicle running;
Means for detecting whether or not the consumption level of the first battery is greater than or equal to a setting ;
A steering angle sensor for detecting a steering angle as a steering amount of the wheel ,
When the engine is stopped while the vehicle is running and the consumption of the first battery or more is detected, the preliminary steering motor is driven by the control system in response to the operation of the operation member instead of the steering motor .
The means for detecting whether or not the consumption level of the first battery is equal to or greater than a set value monitors the response time from the output time of the drive signal of the steering motor to the change time of the detected steering angle by the steering angle sensor, A vehicular steering apparatus, wherein when the response time exceeds a predetermined set time, exhaustion exceeding the setting of the first battery is detected .   The nominal voltage of the first battery is larger than that of the second battery, and the load including the steering motor connected to the first battery includes a load including the preliminary steering motor connected to the second battery. The vehicle steering device according to any one of claims 1 to 3, wherein the vehicle steering device is made larger.

Images