JP2004249913A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device capable of preventing overheat of a motor by detecting generation of a steering disable state during automatic steering. <P>SOLUTION: The automatic steering is released in the process by detecting the occurrence of the steering disable state when a steering angle detection value does not reach a steering angle command value during the automatic steering and cumulative time of the state of a large motor current value reaches prescribed decision time. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric power steering device mounted on a vehicle such as an automobile.
[0002]
[Prior art]
2. Description of the Related Art An electric power steering device is a device that generates a steering assist force by a motor connected to a steering shaft via an electromagnetic clutch according to a steering torque applied to a steering member (steering wheel). In such an electric power steering apparatus, when the rotating shaft of the motor is locked for some reason, a means for preventing the steering from being locked and being unable to be steered is required. For this reason, for example, in the electric power steering device described in Patent Document 1 or 2, the power assist is stopped by detecting the lock of the motor when the relationship between the steering torque and the steering angle is out of the predetermined range. At the same time, the electromagnetic clutch is disengaged to switch to a manual steering device.
[0003]
Further, in the electric power steering device described in Patent Document 3, when the steering torque or the like is equal to or more than a predetermined value, the rotation angular speed of the motor is equal to or less than a reference value, and it is determined that the motor is in a locked state. Stop the assist, disengage the electromagnetic clutch, and switch to the manual steering device.
[0004]
[Patent Document 1]
Japanese Patent No. 2891038 (pages 3 to 5, FIG. 4)
[Patent Document 2]
Japanese Patent No. 2819473 (pages 2-3, FIG. 1)
[Patent Document 3]
Japanese Patent No. 2924516 (pages 3 and 4, FIG. 4)
[0005]
[Problems to be solved by the invention]
In all of the conventional electric power steering devices as described above, the steering torque is taken into consideration in determining whether the motor is locked. However, the automatic parking system currently under development is such that parallel parking and the like are performed by the automatic steering of the electric power steering device without any operation by the driver. Is not available. If the steered wheels hit an obstacle such as a curb during such automatic steering, the state is very similar to the lock of the motor even if the motor is normal. However, in the conventional electric power steering apparatus, this state cannot be detected as locked unless there is information on the steering torque.
Therefore, even if the vehicle cannot be steered due to an obstacle such as a curbstone, it cannot be detected, and the maximum current continues to flow through the motor. As a result, the motor may overheat and the system may stop abnormally. In this case, it takes time to return, and the usability deteriorates.
[0006]
In view of the above conventional problems, an object of the present invention is to provide an electric power steering device capable of detecting that an unsteering state has occurred during automatic steering and preventing overheating of a motor. I do.
[0007]
[Means for Solving the Problems]
An electric power steering device according to the present invention includes a steering device capable of generating a steering assist force by a motor in accordance with a steering torque applied to a steering member, and capable of steering a steered wheel by the motor alone, and A steering amount sensor for detecting a steering amount, and driving the motor in accordance with a steering angle command value, causing the steering device to perform automatic steering, and a predetermined amount based on a steering amount detected by the steering amount sensor. If the steering device determines that the automatic steering corresponding to the steering angle command value has not been performed within the determination time, the control device stops the motor and cancels the automatic steering.
In the electric power steering device configured as described above, when the steered wheels cannot be steered any longer due to an obstacle such as a curb during automatic steering, automatic steering corresponding to the steering angle command value is performed within the determination time. The automatic steering is canceled by the control device after the determination time, and the motor is stopped. Therefore, overheating of the motor is prevented, and abnormal stoppage of the automatic parking system can be prevented.
[0008]
Further, an electric power steering apparatus according to the present invention includes: a steering apparatus capable of generating a steering assist force by a motor in accordance with a steering torque applied to a steering member and capable of turning a steered wheel by the motor alone; A steering amount sensor for detecting a steering amount by the device, a temperature sensor for detecting the temperature of the motor, and an automatic steering control unit that drives the motor in accordance with a steering angle command value and causes the steering device to perform automatic steering. Based on the steering amount detected by the steering amount sensor, determines whether the steering device has performed automatic steering corresponding to the steering angle command value within a determination time set in accordance with the temperature detected by the temperature sensor. The motor is stopped when the steering determination unit determines that the automatic steering corresponding to the steering angle command value is not performed within the determination time within the determination period. It is, or may be provided with an automatic steering cancellation unit cancels the automatic steering.
In the electric power steering device configured as described above, when the steered wheels cannot be steered any longer due to an obstacle such as a curb during automatic steering, automatic steering corresponding to the steering angle command value is performed within the determination time. The automatic steering is canceled by the control device after the determination time, and the motor is stopped. Therefore, overheating of the motor is prevented, and abnormal stoppage of the automatic parking system can be prevented. In addition, since the determination time is set according to the temperature of the motor, overheating of the motor can be accurately prevented in consideration of the temperature.
[0009]
Further, in the electric power steering device, the steering determination unit may determine that the cumulative time during which the steering angle detection value corresponding to the steering amount detected by the steering amount sensor is less than the steering angle command value by a predetermined value or more. When the determination time has been reached, it may be determined that automatic steering corresponding to the steering angle command value has not been performed.
In this case, since the steering angle detection value does not reach the steering angle command value within the determination time, it is possible to easily detect that the steering is disabled.
[0010]
Further, in the electric power steering device, the steering determination unit determines that the steering angle detection value corresponding to the steering amount detected by the steering amount sensor is less than a predetermined value with respect to the steering angle command value, and the motor current value May be determined that the automatic steering corresponding to the steering angle command value has not been performed when the accumulated time in which the steering angle exceeds the predetermined value has reached the determination time.
In this case, it is possible to accurately detect that the steering is disabled due to the fact that the steering angle detection value has not reached the steering angle command value and the accumulated time in the state where the motor load is large has reached the determination time. it can.
[0011]
In the above-described electric power steering apparatus, the determination time may be longer as the difference between the steering angle command value and the steering angle detection value is larger.
In this case, when the steering angle command value is relatively large and the steering takes a considerable time, the determination time becomes long. Therefore, it is possible to prevent the normal automatic steering from being accidentally released halfway. Conversely, when the steering angle command value is relatively small and the steering does not take much time, the determination time becomes short. Therefore, when steering becomes impossible, automatic steering can be quickly released.
[0012]
In the above-described electric power steering apparatus, the determination time may be shortened as the current value of the motor increases.
In this case, when the motor current value is relatively large and the temperature of the motor rises rapidly, the determination time can be shortened to more reliably prevent overheating of the motor. Conversely, when the motor current value is relatively small and the temperature rise of the motor is gradual, the determination time can be lengthened to avoid hasty automatic steering cancellation.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a diagram showing a schematic configuration of an electric power steering device according to an embodiment of the present invention mounted on an automobile. In the figure, a steering device 1 forming a main body of an electric power steering device includes a steering member (steering wheel) 2, an input shaft 3, a torsion bar 4, an output shaft 5 connected to the steering member, and a torsion of the torsion bar 4. , A torque detector 6 for detecting a steering torque, a reduction gear 7 that rotates integrally with the output shaft 5, a motor 8 with a built-in electromagnetic clutch that meshes with the reduction gear 7, and a pinion 9 formed at the lower end of the output shaft 5. A rack and pinion is formed by meshing with the pinion 9 and includes a rack shaft 10 that linearly moves left and right, and a tie rod 12 that connects the rack shaft 10 and the steered wheels 11.
[0014]
The output signal of the torque detector 6 is input to an ECU (Electronic Control Unit) 13 as a control device having a necessary interface and a driver in addition to a CPU, a ROM, a RAM, and the like. Further, a drive current is supplied from the ECU 13 to the motor (including the electromagnetic clutch) 8. Although a power unit for actually supplying a drive current to the motor 8 is actually provided, this power unit is also described in the ECU 13.
[0015]
On the other hand, as a control system element when the electric power steering device is used for automatic steering in the automatic parking system, a temperature sensor 14 for detecting the temperature of the motor 8 and a steering amount (steering angle) based on the rotation of the output shaft 5 are used. A steering amount sensor 15 for detecting is provided. Note that the steering amount sensor 15 may detect the steering amount based on the movement amount of the rack shaft 10. Output signals of the temperature sensor 14 and the steering amount sensor 15 are input to the ECU 13. Further, a signal of a steering angle command value is input to the ECU 13 from a central control device (not shown) of the vehicle. The output signals of the temperature sensor 14 and the steering amount sensor 15 are also sent to the central control device.
[0016]
The ECU 13 includes a normal steering control unit 131, an automatic steering control unit 132, an automatic steering release unit 133, and a steering determination unit 134 as internal functions configured by software (processing in a flowchart described later). The normal steering control unit 131 causes the motor 8 to generate a steering assist force based on an output signal from the torque detector 6 that detects a steering torque applied to the steering member 2. The automatic steering control unit 132 drives the motor 8 according to the steering angle command value, and causes the steering device 1 to perform automatic steering. The steering determination unit 134 controls the steering device 1 to turn the steering device 1 within the determination time set in accordance with the temperature detected by the temperature sensor 14 based on the steering amount detected by the steering amount sensor 15 and, if necessary, the current value of the motor 8. It is determined whether the automatic steering corresponding to the angle command value has been performed. The automatic steering canceling unit 133 stops the motor 8 and cancels the automatic steering when the steering determining unit 134 determines that the automatic steering corresponding to the steering angle command value is not performed within the determination time. .
[0017]
In the electric power steering apparatus configured as described above, the steering angle command value is, for example, 0 during normal running, and normal control is performed by the normal steering control unit 131. Specifically, the steering torque applied to the steering member 2 is detected by the torque detector 6, and the motor 8 is driven by the ECU 13 (normal steering control unit 131) that has received the output signal to generate a steering assist force. .
On the other hand, when the driver operates a button or the like to start an automatic parking system mounted on the vehicle and the motor 8 is driven under the control of the automatic parking system, the driver does not perform any steering operation, The steered wheels 11 are steered by the motor 8 alone.
[0018]
Hereinafter, first to third embodiments of the processing operation executed by the ECU 13 during the operation of the automatic parking system will be described with reference to FIGS.
<< 1st Example >>
FIG. 2 is a flowchart showing a first embodiment of the processing operation. When the automatic parking system is started, a steering angle command value calculated from a stop position of the vehicle, a garage entry target position, and the like at that time is input to the ECU 13. Thereby, the automatic steering is started, and the motor 8 is driven according to the steering angle command value. In step S21, the CPU of the ECU 13 (hereinafter, simply referred to as CPU) determines whether or not the operation mode is the automatic operation mode based on the presence or absence of the steering angle command value. In this case, since the steering angle command value has arrived, the operation mode is the automatic operation mode, and the CPU proceeds to step S22, where (steering angle command value−steering angle detection value) is equal to or more than a predetermined value X (for example, 10 degrees). It is determined whether or not there is. Here, the steering angle detection value means a steering angle of the steered wheels 11 corresponding to an output signal of the steering amount sensor 15.
[0019]
The determination in step S22 differs depending on the steering angle command value. For example, if the steering angle command value is 30 degrees and the detected steering angle value immediately after startup is almost 0, the difference is 30 degrees, and the determination result is Is YES, the CPU proceeds to step S23. Here, the CPU determines whether or not the motor current value supplied from the ECU 13 itself is larger than a predetermined value A. When the steered wheels 11 are steered smoothly, the value of A is set so that the motor current value is less than A. Therefore, in that case, the CPU returns to step S21, and the CPU returns to steps S21 to S23. repeat.
[0020]
If the automatic steering proceeds smoothly, the difference between the steering angle command value and the steering angle detection value becomes smaller than the predetermined value X, and the process of returning from step S22 to S21 is repeated. When the steering angle detection value reaches the steering angle command value, the steering angle command value becomes 0 (that is, no command comes), and the process jumps from NO in step S21 to step S26. In step S26, the motor 8 is stopped, and the shift to the normal steering mode is performed. If the steering angle command value is less than X from the beginning, the processing from step S21 to step S22 is repeated, and when the steering angle command value becomes 0, the routine jumps to step S26, the motor 8 stops, and the normal steering mode is set. Is performed.
In this manner, if the state that the difference between the steering angle command value and the detected steering angle is equal to or more than the predetermined value X and the motor current value exceeds A has never occurred during the automatic steering, the step When the detected steering angle reaches the steering angle command value without executing S24 and S25, the automatic steering is completed, and the control returns to the normal steering.
[0021]
Next, during the automatic steering, if a state occurs in which the difference between the steering angle command value and the detected steering angle value is equal to or more than the predetermined value X and the motor current value exceeds A, the CPU proceeds from step S23 to S24. , A fail counter (FC: initial value 0) is counted (processing of FC = FC + 1). Subsequently, in step S25, it is monitored whether or not the count value of the fail counter is equal to or larger than the set value B (step S25 → repeated steps S21 to S25). The set value B is a value set from the viewpoint of preventing the motor 8 from overheating, and is set based on the temperature of the motor 8 detected by the temperature sensor 14, and is set to a smaller value as the temperature is higher.
[0022]
Here, the difference between the steering angle command value and the steering angle detection value is equal to or more than the predetermined value X and the cause of the state where the motor current value exceeds A is that, for example, the frictional resistance of the road surface is large. For such transient reasons, the motor current value becomes A or less without delay, or the difference between the steering angle command value and the detected steering angle becomes less than X. Therefore, before the count value of the fail counter reaches B, the steering angle detection value reaches the steering angle command value, and the automatic steering is completed.
[0023]
On the other hand, when the steered wheel 11 hits an obstacle such as a curb and stops during automatic steering, the steering angle detection value does not increase from that point, and the state where the difference from the steering angle command value is X or more continues. There are cases. In this case, the rotation of the motor 8 is forcibly stopped, so that the motor current value exceeds A. Accordingly, the CPU proceeds from step S23 to S24, counts the fail counter (FC), and subsequently monitors in step S25 whether the count value of the fail counter is equal to or greater than the set value B (step S25 → S21-S21). S25). Then, when the fail counter reaches B, that is, after the lapse of the accumulated time obtained by multiplying the count number by the count period (routine processing time), the motor 8 is stopped and the operation mode is shifted to the normal steering mode (step S26).
[0024]
In this manner, the accumulated time during which the detected steering angle value is less than the predetermined value X with respect to the steering angle command value and the motor current value is equal to or greater than A reaches the determination time corresponding to the set value B. As a result, the CPU determines that the automatic steering corresponding to the steering angle command value has not been performed, and cancels the automatic steering halfway. Therefore, when the steered wheels 11 cannot be steered any longer due to an obstacle such as a curbstone, the automatic steering is canceled after the determination time and the motor 8 is stopped, so that overheating of the motor 8 is prevented. As a result, abnormal stoppage of the automatic parking system can be prevented, and it is possible to avoid an undesired situation in which it takes a long time to return due to the stoppage of the system. Further, the above determination is made based on the logical product of three elements of the steering angle, the motor current value, and the determination time. Therefore, an accurate determination can be made.
[0025]
Further, the value of B is set by the temperature of the motor 8 (the temperature before the start of automatic steering), and the smaller the value, the smaller the value. Therefore, the higher the temperature, the shorter the determination time becomes. As a result, when the temperature is originally high and the temperature of the motor 8 rises quickly, the automatic steering can be quickly released within a short determination time, and overheating of the motor 8 can be prevented. Conversely, when the temperature is originally low and the temperature rise of the motor 8 is gradual, it is possible to avoid the hasty automatic steering cancellation due to the long determination time. That is, overheating of the motor 8 can be properly prevented in consideration of the temperature.
[0026]
When the steering angle command value is a small value less than X, the fail counter is not counted, so even if the steered wheel 11 hits an obstacle such as a curb, the ECU 13 does not cancel the automatic steering halfway. Narrow steering is possible by elastic deformation of the tire.
[0027]
<< 2nd Example >>
FIG. 3 is a flowchart showing a second embodiment of the processing operation. When the automatic parking system starts, the automatic steering is started and the motor 8 is driven according to the steering angle command value, as in the case of the first embodiment. In step S31, the CPU determines whether or not the operation mode is the automatic operation mode based on the presence or absence of the steering angle command value. Here, since the steering angle command value has arrived, the operation mode is the automatic operation mode, and the CPU proceeds to step S32 to determine whether (steering angle command value−steering angle detection value) is equal to or more than a predetermined value X (for example, 10 degrees). Judge.
[0028]
The determination in step S32 is, for example, assuming that the steering angle command value is 30 degrees and the detected steering angle value immediately after startup is almost 0, the difference is 30 degrees, and the determination result is YES. Proceed to S33. In step S33, the CPU counts a fail counter (FC1: initial value 0) (processing of FC1 = FC1 + 1). Subsequently, in step S34, it is determined whether or not the count value of the fail counter is equal to or greater than the set value B. This B is a value set from the viewpoint of preventing the motor 8 from overheating.
[0029]
Further, as shown in FIG. 4A, when the value of B is (steering angle command value−steering angle detection value) = X, ₀ And increases in proportion to (steering angle command value−steering angle detection value). Also, the value of B is set by shifting in the direction of the vertical axis as indicated by the dotted line depending on the temperature of the motor 8 (the temperature before the start of the automatic steering), and becomes smaller as the temperature becomes higher. Therefore, the larger the difference between the steering angle command value and the detected steering angle value, the longer the value of B, that is, the determination time, and if the difference is the same, the higher the temperature of the motor 8, the shorter the determination time.
[0030]
Since the count value of the fail counter is less than B at the initial time, the CPU proceeds to step S35, where the CPU determines whether the motor current value supplied from the ECU 13 itself is larger than a predetermined value A. to decide. When the steered wheels 11 are steered smoothly, the value of A is set so that the motor current value is less than A. Therefore, in that case, the CPU returns to step S31 and returns to steps S31 to S35. repeat.
[0031]
If the automatic steering proceeds smoothly, the difference between the steering angle command value and the steering angle detection value becomes smaller than the predetermined value X, and the process of returning from step S32 to S31 is repeated. When the steering angle detection value reaches the steering angle command value, the steering angle command value becomes 0 (that is, no command comes), and the process jumps from NO in step S31 to step S38. In step S38, the motor 8 is stopped, and the shift to the normal steering mode is performed. If the steering angle command value is less than X from the beginning, the processing from step S31 to step S32 is repeated, and when the steering angle command value becomes 0, the routine jumps to step S38, the motor 8 stops, and the normal steering mode is set. Is performed.
[0032]
Next, if the difference between the steering angle command value and the steering angle detection value is equal to or larger than the predetermined value X and the motor current value exceeds A during automatic steering, the CPU proceeds from step S35 to S36. , The fail counter (FC2: initial value 0) is counted (processing of FC2 = FC2 + 1). Subsequently, in step S37, it is determined whether or not the count value of the fail counter (FC2) is equal to or greater than the set value C, and if it is less than C, steps S31 to S37 are repeated. During this repetitive processing, the two fail counters (FC1 and FC2) each accumulate count values.
[0033]
The value of C is a value set from the viewpoint of preventing overheating of the motor 8, and as shown in FIG. ₀ And decreases in proportion to the motor current value from A to the maximum value. Also, the value of C is set by shifting in the direction of the vertical axis as indicated by the dotted line depending on the temperature of the motor 8 (the temperature before the start of automatic steering), and the value becomes smaller as the temperature becomes higher. Accordingly, the larger the motor current value, the shorter the value of C, that is, the determination time, and if the motor current value is the same, the higher the temperature of the motor 8, the shorter the determination time.
[0034]
Here, the cause of the occurrence of the state where the difference between the steering angle command value and the steering angle detection value is equal to or more than the predetermined value X and the motor current value exceeds A is caused by, for example, a large frictional resistance on the road surface. For transient reasons, the motor current value becomes A or less without delay, or the difference between the steering angle command value and the steering angle detection value becomes less than X. Therefore, before the count values of the fail counter FC1 and the fail counter FC2 reach B and C, respectively, the detected steering angle reaches the steering angle command value, and the automatic steering is completed.
[0035]
On the other hand, when the steered wheel 11 hits an obstacle such as a curb and stops during automatic steering, the state where the difference from the steering angle command value is X or more continues because the steering angle detection value does not increase from that point. There are cases. In this case, the rotation of the motor 8 is forcibly stopped, so that the motor current value exceeds A. Therefore, the CPU executes steps S33 and S36, and when the fail counter FC1 reaches B in step S34, or when the fail counter FC2 reaches C in step S37, the motor 8 is stopped and the normal steering is performed. The mode shifts to the mode (step S38).
[0036]
In this way, the accumulated time of the state where the steering angle detection value is less than the predetermined value X with respect to the steering angle command value has reached the predetermined determination time, or the steering angle detection value is less than the steering angle command value. As a result, the accumulated time of the state in which the motor current value is not less than A and the motor current value is not less than the predetermined value X has reached the predetermined judgment time, so that the CPU does not perform the automatic steering corresponding to the steering angle command value. And the automatic steering is canceled halfway. Accordingly, when the steered wheels 11 cannot be steered any longer due to an obstacle such as a curbstone, the automatic steering is canceled and the motor 8 is stopped, so that overheating of the motor 8 is prevented. Thereby, abnormal stop of the automatic parking system can be prevented. Further, the values of B and C are set according to the temperature of the motor 8 (the temperature before the start of the automatic steering), and the smaller the value is, the smaller the value is. Thus, as in the case of the first embodiment, overheating of the motor 8 can be accurately prevented in consideration of the temperature.
[0037]
In the second embodiment, (1) the accumulated time during which the steering angle detection value is less than the predetermined value X with respect to the steering angle command value has reached the predetermined determination time; and (2) the steering angle detection The automatic steering is performed under any of the two conditions that the accumulated value of the state in which the value is less than the predetermined value X with respect to the steering angle command value and the motor current value is more than A reaches the predetermined determination time. Because the steering angle detection value is insufficient for the steering angle command value by a predetermined value X or more and the accumulated time of the state in which the motor current value is A or more has reached the predetermined determination time. As compared with the first embodiment in which the condition of (1) is cancelled, the automatic steering can be canceled more reliably because the automatic steering can be canceled only under the condition (1).
[0038]
Further, in the second embodiment, the value of B is increased as the difference between the steering angle command value and the detected steering angle value increases. Therefore, when the steering angle command value is relatively large, that is, the time corresponding to the turning operation. In such a case, the determination time can be increased to prevent the normal automatic steering from being erroneously released halfway. Conversely, when the steering angle command value is relatively small and the steering does not take much time, the determination time becomes short. Therefore, when steering becomes impossible, automatic steering can be quickly released.
Further, in the second embodiment, the value of C decreases as the motor current value increases. Therefore, when the temperature of the motor 8 rises rapidly, the determination time is shortened to more reliably prevent the motor 8 from overheating. can do. Conversely, when the motor current value is relatively small and the temperature rise of the motor 8 is gradual, the determination time can be lengthened to avoid the hasty release of the automatic steering.
[0039]
As in the case of the first embodiment, when the steering angle command value is a small value less than X, the fail counter is not counted, so that even if the steered wheel 11 hits an obstacle such as a curb, the ECU 13 performs automatic steering. Although the steering is not released halfway, a small steering is possible by elastic deformation of the tire.
[0040]
<< 3rd Example >>
FIG. 5 is a flowchart showing a third embodiment of the processing operation. Steps S51 to S56 of this flowchart are the same as steps S21 to S26 of the first embodiment, respectively, and a description thereof will be omitted. However, the set value C in step S55 gives a characteristic that changes according to the motor current value, similarly to FIG. 4B in the second embodiment. In this case, in addition to the operation and effect of the first embodiment, the value of C decreases as the motor current value increases. Therefore, when the temperature of the motor 8 rises sharply, the determination time is shortened, and the motor is more reliably set. 8 can be prevented from overheating. Conversely, when the motor current value is relatively small and the temperature rise of the motor 8 is gradual, the determination time can be lengthened to avoid the hasty release of the automatic steering.
[0041]
In the first to third embodiments, if the set value B or C of the fail counter is set to the minimum value (for example, 1), the determination time becomes substantially 0, and the automatic steering is immediately released. Can be.
Further, the change characteristics of the set values B and C of the fail counter shown in FIG. 4 are linear, but if necessary, a curve, a polygonal line, or a stepwise characteristic may be added.
Although the first to third embodiments each include a step of counting the fail counter based on the motor current value, this step is omitted, and the difference between the steering angle command value and the detected steering angle is omitted. The automatic steering may be simply canceled only by the lapse of the determination time by the fail counter based on the following.
[0042]
【The invention's effect】
According to the electric power steering device of the present invention configured as described above, when the steered wheels can no longer be steered by an obstacle such as a curb during automatic steering, the automatic steering is performed by the control device after the determination time. It is released and the motor stops. Therefore, overheating of the motor is prevented, and abnormal stoppage of the automatic parking system can be prevented.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an electric power steering device according to an embodiment of the present invention which is mounted on an automobile.
FIG. 2 is a flowchart showing a first embodiment of a processing operation executed by the ECU in the electric power steering device of FIG. 1 when the automatic parking system is operated.
FIG. 3 is a flowchart showing a second embodiment of a processing operation executed by the ECU in the electric power steering device of FIG. 1 when the automatic parking system operates.
FIG. 4 is a graph showing a change characteristic of a set value of a fail counter in the flowchart of FIG.
FIG. 5 is a flowchart showing a third embodiment of a processing operation executed by the ECU in the electric power steering device of FIG. 1 when the automatic parking system operates.
[Explanation of symbols]
1 Steering device
2 Steering members
8 motor
11 Steering wheels
13 ECU (control device)
14 Temperature sensor
15 Steering amount sensor
132 Automatic steering control unit
133 Automatic steering release section
134 Steering judgment unit

Claims (6)

A steering device that generates a steering assist force by a motor according to a steering torque applied to a steering member, and that can steer a steered wheel by the motor alone;
A steering amount sensor for detecting a steering amount by the steering device;
The motor is driven in accordance with a steering angle command value to cause the steering device to perform automatic steering, and the steering device is controlled by the steering device within a predetermined determination time based on a steering amount detected by the steering amount sensor. An electric power steering device, comprising: a control device that stops the motor when it is determined that automatic steering corresponding to the angle command value is not being performed, and cancels automatic steering. A steering device that generates a steering assist force by a motor according to a steering torque applied to a steering member, and that can steer a steered wheel by the motor alone;
A steering amount sensor for detecting a steering amount by the steering device;
A temperature sensor for detecting the temperature of the motor,
An automatic steering control unit that drives the motor according to a steering angle command value, and causes the steering device to perform automatic steering,
Based on the steering amount detected by the steering amount sensor, whether or not the steering device has performed automatic steering corresponding to the steering angle command value within a determination time set according to the temperature detected by the temperature sensor, A steering determination unit that determines
An automatic steering canceling unit that stops the motor and cancels automatic steering when it is determined that the automatic steering corresponding to the steering angle command value is not performed within the determination time by the steering determination unit. An electric power steering device, characterized in that: The steering determination unit is configured such that the cumulative time of a state in which a steering angle detection value corresponding to a steering amount detected by the steering amount sensor is insufficient by a predetermined value or more with respect to the steering angle command value has reached the determination time. 3. The electric power steering apparatus according to claim 2, wherein it is determined that the automatic steering corresponding to the steering angle command value is not performed. The steering determination unit is configured such that a steering angle detection value corresponding to a steering amount detected by the steering amount sensor is less than a predetermined value with respect to the steering angle command value, and a current value of the motor exceeds a predetermined value. The electric power steering apparatus according to claim 2, wherein it is determined that the automatic steering corresponding to the steering angle command value is not performed when the accumulated time of the state reaches the determination time. 5. The electric power steering apparatus according to claim 3, wherein the determination time becomes longer as the difference between the steering angle command value and the steering angle detection value increases. The electric power steering apparatus according to claim 4, wherein the determination time is shortened as the current value of the motor increases.

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