JP2005028900A - Battery state judging device in electric steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and accurately judge the state of a battery which feeds power to an electric steering device equipped with a plurality of actuators. <P>SOLUTION: This steer-by-wire type steering device steers wheels W by controlling the operation of the first and second steering actuators 14 and 17 to which power is fed from the battery 26 by an electronic control unit U. The electronic control unit U takes out a large electric current from the battery 26 by driving one of the first and second steering actuators 14 and 17 in a right turn steering direction, and at the same time, driving the other in a left turn steering direction, and judges the state of the battery 26 based on a descent amount of the terminal voltage V of the battery 26 which is output by a voltage sensor Sf during that period. Thus, a large current can easily be made to flow to the first and second steering actuators 14 and 17, and the state of the battery 26 can accurately be judged. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric steering apparatus that steers a wheel by controlling operations of a plurality of actuators fed from a battery by a control means, and more particularly to a battery state determination apparatus thereof.
[0002]
[Prior art]
The mechanical connection between the steering wheel and the steering gear box is cut off, and the control means controls the drive of the actuator provided in the steering gear box based on the electric signal generated by the operation of the steering wheel to steer the left and right wheels. In steer-by-wire steering systems, if the battery, which is the power source, deteriorates, it may not be possible to reliably steer the wheels. It is necessary to exchange.
[0003]
Conventionally, the deterioration state of the battery and the remaining capacity are determined by monitoring the rate of decrease of the terminal voltage while taking a large current from the battery, and determining that the battery is abnormal when the rate of decrease exceeds a threshold value.
[0004]
Further, what performs battery life extension and deterioration determination is known from Patent Document 1 and Patent Document 2 below, and one that measures the remaining battery capacity of an electric vehicle is known from Patent Document 3 below.
[0005]
[Patent Document 1]
JP 2002-542576 A [Patent Document 2]
JP 2002-190329 A [Patent Document 3]
Japanese Patent Laid-Open No. 6-54402
[Problems to be solved by the invention]
By the way, in the above conventional method of determining abnormality by monitoring a decrease rate of the terminal voltage while taking out a large current from a battery that supplies power to the steer-by-wire steering device, a large current is applied to the battery with a large load. There is a problem that requires a special circuit and a control device for flowing the air. In addition, if a large current is supplied to the actuator of the steer-by-wire steering device to make the above determination, a large current cannot be supplied to the actuator unless measures such as fixing the wheels to be steered are taken. After all, there is a problem that costs increase.
[0007]
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to make it possible to easily and accurately determine the state of a battery that supplies power to an electric steering apparatus including a plurality of actuators.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, in the electric steering apparatus that steers the wheel by controlling the operation of the plurality of actuators fed from the battery by the control means, A voltage sensor for detecting a terminal voltage and inputting it to the control means; the control means drives at least one of the plurality of actuators in the right turning direction and drives at least one other in the left turning direction; A battery state determination device in an electric steering device is proposed, in which the state of the battery is determined based on the amount of decrease in the terminal voltage output by the voltage sensor during that time.
[0009]
According to the above configuration, at least one of the plurality of actuators that steer the wheels is driven in the right steering direction, and at least one other is driven in the left steering direction, and power is supplied to the plurality of actuators in the meantime. The terminal voltage of the battery to be detected is detected by a voltage sensor, and the state of the battery is determined based on the amount of decrease in the terminal voltage. Therefore, a large current can be easily passed through a plurality of actuators to accurately determine the battery state. it can. In addition, since the existing control means for controlling the operation of the plurality of actuators is used, it is not necessary to provide special control means, and can be realized at low cost.
[0010]
According to the invention described in claim 2, in addition to the configuration of claim 1, the control means controls the output torque of the plurality of actuators so that the wheels are not steered. A battery state determination device in an electric steering device is proposed.
[0011]
According to the above configuration, the output torque of the plurality of actuators is controlled so that the wheels are not steered, so that unnecessary steering of the wheels can be prevented and the driver's uncomfortable feeling can be eliminated.
[0012]
The first and second steering actuators 14 and 17 of the embodiment correspond to the actuator of the present invention, and the electronic control unit U of the embodiment corresponds to the control means of the present invention.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.
[0014]
As shown in FIG. 1, a steering gear box 11 that steers wheels W of an automobile includes a rack bar 12 that can slide in the left-right direction of the vehicle body, and both ends of the rack bar 12 have left and right tie rods 13 and 13. To the left and right wheels W, W. A pinion 15 rotated by a first steering actuator 14 made of an electric motor meshes with a rack 16 formed on the rack bar 12, and when the first steering actuator 14 is driven, the rack bar 12 moves to the left and right of the vehicle body via the pinion 15 and the rack 16. Sliding in the direction, the left and right wheels W, W are steered through the tie rods 13,13.
[0015]
A second steering actuator 17 made of an electric motor and an annular drive gear 18 rotated thereby are arranged so as to surround the outer periphery of the rack bar 12. A male screw member 21 meshes with a female screw member 20 supported by a bracket 19 fixed to the rack bar 12, and a driven gear 22 provided at one end of the male screw member 21 meshes with the drive gear 18. Accordingly, when the second steering actuator 17 is driven, the rotation of the drive gear 18 is transmitted to the male screw member 21 via the driven gear 22, and the female screw member 20 that meshes with the rotating male screw member 21 moves in the left-right direction of the vehicle body. The bar 12 slides in the left-right direction of the vehicle body and the left and right wheels W, W are steered.
[0016]
A steering reaction force generating means 25 is provided at the lower end of the steering shaft 24 integrated with the steering wheel 23. The steering reaction force generating means 25 applies a pseudo steering reaction force to the steering wheel 23 by an electric motor or hydraulic pressure, and the direction and magnitude of the steering reaction force can be arbitrarily controlled.
[0017]
An electronic control unit U connected to the battery 26 and controlling the operation of the first steering actuator 14, the second steering actuator 17 and the steering reaction force generating means 25 has a steering angle δ detected by the steering angle sensor Sa and a steering torque. The steering torque T detected by the sensor Sb, the vehicle speed Vv detected by the vehicle speed sensor Sc, the rack position P detected by the rack position sensor Sd, the current I from the battery 26 detected by the current sensor Se, and the voltage sensor Sf The detected terminal voltage V of the battery 26 is input.
[0018]
Next, the operation of the embodiment having the above configuration will be described.
[0019]
The first steering actuator 14 is used during normal operation, and the second steering actuator 17 is used as a backup when the first steering actuator 14 fails. When the driver operates the steering wheel 23 at the normal time when the first steering actuator 14 functions normally, the steering angle δ detected by the steering angle sensor Sa, the vehicle speed Vv detected by the vehicle speed sensor Sc, and the rack position sensor Sd are detected. The rack position P is input to the electronic control unit U. For example, the electronic control unit U drives the first steering actuator 14 so as to obtain the turning angle γ of the wheels W and W proportional to the steering angle δ of the steering wheel 23, and the wheel W via the steering gear box 11. , W is steered.
[0020]
At this time, feedback control is performed so that the rack position P detected by the rack position sensor Sd (that is, the turning angle γ of the wheels W, W) matches the target position. For example, when the vehicle speed Vv detected by the vehicle speed sensor Sc is high, the target turning angle of the wheels W, W is decreased, and when the vehicle speed Vv is low, the target turning angle of the wheels W, W is increased. Sometimes, it is possible to improve the straight running stability of the vehicle and facilitate the handling of the vehicle at a low speed.
[0021]
In the steer-by-wire type steering device, since the steering reaction force from the wheels W, W does not act on the steering wheel 23, the steering reaction force generating means 25 is driven by the command from the electronic control unit U, and the steering wheel 23 is steered. It is necessary to apply reaction force. The target steering torque at that time is set so as to decrease as the steering angle δ increases, for example. The drive of the steering reaction force generating means 25 is feedback-controlled so that the steering torque T detected by the steering torque sensor Sb matches the target steering torque. In this way, by applying a pseudo steering reaction force to the steering wheel 23 by the steering reaction force generating means 25, the driver's uncomfortable feeling can be eliminated.
[0022]
When the vehicle speed Vv detected by the vehicle speed sensor Sc is small, a small steering reaction force is generated in the steering reaction force generating means 25, and when the vehicle speed Vv detected by the vehicle speed sensor Sc is large, the steering reaction force generating means 25 is greatly steered. By generating the reaction force, it is possible to stabilize the vehicle behavior during high-speed driving and to facilitate the steering of the driver when entering the garage.
[0023]
Further, when the first steering actuator 14 fails, the electronic control unit U controls the second steering actuator 17 in the same manner, so that the steering of the wheels W and W can be continued without any trouble.
[0024]
By the way, in the steer-by-wire steering device, when the remaining capacity of the battery 26 decreases and the electronic control unit U or the first and second steering actuators 14 and 17 become inoperable, the mechanical function of the steering wheel and the steering gear box is increased. Since the connection is broken, the wheels W and W may not be steered accurately. Therefore, the state of the battery 26 is constantly monitored, and when the battery 26 is deteriorated or the remaining capacity is reduced, the battery 26 is charged or replaced, and the steer-by-wire steering device is used. It is necessary to ensure operation.
[0025]
Therefore, in this embodiment, for example, immediately after the ignition switch is turned on, a reverse drive command is output to the first and second steering actuators 14 and 17 by a command from the electronic control unit U, and the wheels W and W are steered. Without load, only the load is applied to the first and second steering actuators 14 and 17. For example, by generating an output torque in the right steering direction at the first steering actuator 14 and generating an output torque in the left steering direction at the second steering actuator 17, the wheels W and W Avoid being steered. For this purpose, the output torques of the first and second steering actuators 14 and 17 may be controlled so that the rack position P detected by the rack position sensor Sd does not change.
[0026]
In this way, the current I flowing through the first and second steering actuators 14 and 17 is detected by the current sensor Se, and the current I is increased until it reaches a predetermined value. In this state, the terminal voltage V of the battery 26 detected by the voltage sensor Sf is monitored, and a decrease amount of the terminal voltage V in a predetermined time is detected. When the battery 26 is deteriorated or the remaining capacity is reduced, the amount of decrease in the terminal voltage when the current is taken out becomes large. Therefore, when the amount of decrease in the terminal voltage V during the predetermined time exceeds the threshold value. When it is determined that the battery 26 has deteriorated or the remaining capacity has been reduced, and a warning is issued to the driver to prompt the battery 26 to be charged or replaced, the steer-by-wire steering device may malfunction. Can be avoided in advance.
[0027]
As described above, paying attention to the fact that the steer-by-wire steering device includes the first and second steering actuators 14 and 17, the first and second steering actuators 14 and 17 are simultaneously driven in the opposite directions. By doing so, a large load current can be passed without turning the wheels W, W. Moreover, since the electronic control unit U originally has a function of controlling the driving of the first and second steering actuators 14 and 17, it is not necessary to newly provide a special control means for determining the state of the battery 26. It can be realized at low cost. Further, since the steering of the wheels W and W is not performed, the driver does not feel uncomfortable.
[0028]
Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.
[0029]
For example, although the second steering actuator 17 is provided as a backup for the first steering actuator 14 in the embodiment, the first and second steering actuators 14 and 17 may be used together at all times.
[0030]
In the embodiment, the steer-by-wire type steering device is exemplified as the electric steering device. However, the electric steering device may be an electric power steering device that assists the steering operation of the driver.
[0031]
In the embodiment, when determining the state of the battery 26, the first and second steering actuators 14 and 17 are driven so that the wheels W and W are not steered. If the driving directions of 17 are opposite to each other, the wheels W, W may be steered.
[0032]
In addition, the steer-by-wire steering device of the embodiment includes two steering actuators 14 and 17, but may include three or more steering actuators.
[0033]
The determination of the battery state is desirably performed when the vehicle is stopped, but can also be performed when the vehicle is traveling straight.
[0034]
【The invention's effect】
As described above, according to the first aspect of the present invention, at least one of the plurality of actuators that steer the wheels is driven in the right steering direction, and at least one other is driven in the left steering direction. In the meantime, the terminal voltage of the battery that supplies power to the plurality of actuators is detected by a voltage sensor, and the state of the battery is determined based on the amount of decrease in the terminal voltage. The state of the battery can be accurately determined. In addition, since the existing control means for controlling the operation of the plurality of actuators is used, it is not necessary to provide special control means, and can be realized at low cost.
[0035]
According to the invention described in claim 2, since the output torque of the plurality of actuators is controlled so that the wheel is not steered, unnecessary steering of the wheel can be prevented to eliminate the driver's uncomfortable feeling. it can.
[Brief description of the drawings]
FIG. 1 is a block diagram of a control system of a steer-by-wire steering system.
14 First steering actuator (actuator)
17 Second steering actuator (actuator)
26 Battery Sf Voltage sensor U Electronic control unit (control means)
V Battery terminal voltage W Wheel

Claims (2)

In the electric steering device for turning the wheel (W) by controlling the operation of the plurality of actuators (14, 17) fed from the battery (26) by the control means (U),
A voltage sensor (Sf) that detects a terminal voltage (V) of the battery (26) and inputs the detected voltage to the control means (U) is provided, and the control means (U) includes at least one of the actuators (14, 17). The battery (26) is driven based on the amount of decrease in the terminal voltage (V) output by the voltage sensor (Sf) during driving in the right turning direction and at least one other in the left turning direction. A battery state determination device in an electric steering device, characterized in that The battery in the electric steering apparatus according to claim 1, wherein the control means (U) controls output torques of the plurality of actuators (14, 17) so that the wheels (W) are not steered. State determination device.

Images