JP2006051912A - Electric power steering device - Google Patents

Electric power steering device Download PDF

Info

Publication number
JP2006051912A
JP2006051912A JP2004236697A JP2004236697A JP2006051912A JP 2006051912 A JP2006051912 A JP 2006051912A JP 2004236697 A JP2004236697 A JP 2004236697A JP 2004236697 A JP2004236697 A JP 2004236697A JP 2006051912 A JP2006051912 A JP 2006051912A
Authority
JP
Japan
Prior art keywords
drive prohibition
current
steering
map
vehicle speed
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2004236697A
Other languages
Japanese (ja)
Inventor
Kaname Aoki
要 青木
Original Assignee
Favess Co Ltd
Koyo Seiko Co Ltd
Toyoda Mach Works Ltd
光洋精工株式会社
株式会社ファーベス
豊田工機株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Favess Co Ltd, Koyo Seiko Co Ltd, Toyoda Mach Works Ltd, 光洋精工株式会社, 株式会社ファーベス, 豊田工機株式会社 filed Critical Favess Co Ltd
Priority to JP2004236697A priority Critical patent/JP2006051912A/en
Publication of JP2006051912A publication Critical patent/JP2006051912A/en
Pending legal-status Critical Current

Links

Images

Abstract

An abnormal condition is detected earlier even when the vehicle speed is high, and steering assist is stopped.
A target current setting / determination unit (12) includes an assist map (122) indicating a correspondence relationship between a current target value (It) and a steering torque (T), and an assist current setting unit that outputs the current target value It with reference to the assist map (122). 121, a drive prohibition map 124 that includes a condition for stopping steering assist as a predetermined drive prohibition region, and a drive prohibition determination unit 123 that determines whether to stop steering assist with reference to the drive prohibition map 124 Including. The drive prohibition determination unit 123 selects the drive prohibition map B including a relatively wide drive prohibition region only when the vehicle speed V is large and the detected value Is of the motor current is small (high speed / low output state), and the current target When the value It and the steering torque T match the conditions shown in the selected drive prohibition map B, the steering assistance can be stopped quickly and surely by performing control to stop the motor.
[Selection] Figure 3

Description

  The present invention relates to an electric power steering apparatus that applies a steering assist force to a steering mechanism of a vehicle by driving an electric motor.

  2. Description of the Related Art Conventionally, an electric power steering apparatus that applies a steering assist force to a steering mechanism by driving an electric motor in accordance with a steering torque applied to a steering wheel (steering wheel) by a driver has been used. This electric power steering apparatus is provided with a torque sensor for detecting a steering torque applied to a steering wheel as an operation means for steering, and a table called an assist map is provided based on the steering torque detected by the torque sensor. By referencing, a target value of current to be supplied to the electric motor (hereinafter referred to as “current target value”) is set. Note that this assist map is normally determined such that the target current value decreases (that is, the steering assist force decreases) as the vehicle speed increases. Then, a command value to be given to the drive means of the electric motor is generated by proportional integration calculation based on the deviation between the current target value and the value of the current actually flowing to the electric motor. The drive means of the electric motor is turned on / off according to the PWM signal generation circuit that generates a pulse width modulation signal (hereinafter referred to as “PWM signal”) having a duty ratio corresponding to the command value, and the duty ratio of the PWM signal. A motor drive circuit configured using a power transistor, and a voltage corresponding to the duty ratio is applied to the electric motor. The current flowing through the electric motor by this voltage application is detected by a current detector, and the difference between the current target value and the detected current value is used as a deviation for generating the command value.

In such a conventional electric power steering device, these abnormal states are detected and steering assistance is performed so that steering assistance or excessive steering assistance that is opposite to the original steering assistance direction due to abnormal operation of the device is not performed. There is something that controls to prohibit. For example, if the current detector fails and the detected current value is always 0, the difference from the current target value does not always become 0, and excessive steering assistance is performed. Then, when the driver steers to stop the rotation of the steering wheel due to the excessive steering assistance, the detected value of the steering torque further increases, so that the excessive steering assistance becomes further excessive (becomes a hunting state). Accordingly, it is detected whether or not the current target value or the command value exceeds a predetermined threshold value, and if it exceeds, control for stopping the steering assist is performed. Such control increases the safety of steering.
Japanese Patent No. 2891069

  However, since the steering assist force is small when the vehicle speed is high due to the characteristics of the assist map, the current device does not easily exceed the threshold value even if it is in the hunting state. As a result, even if it is preferable to stop the steering assist, there is a possibility that the control for stopping the steering assist may not be performed.

  Therefore, an object of the present invention is to provide an electric power steering device capable of stopping steering assistance by detecting an abnormal state earlier even when the vehicle speed is high.

A first invention is an electric power steering device that applies a steering assist force to a steering mechanism of a vehicle by driving an electric motor in accordance with a steering torque applied by an operation means for vehicle steering,
A vehicle speed sensor for detecting the traveling speed of the vehicle as a vehicle speed;
A torque sensor for detecting the steering torque;
Motor current detecting means for detecting a current flowing through the electric motor;
Target value setting means for setting a target value of a current to be supplied to the electric motor in order to give the steering assist force based on the steering torque detected by the torque sensor;
Control means for controlling the electric motor based on the target value of the current;
Based on the vehicle speed and the current detected by the motor current detecting means, a plurality of drive prohibiting conditions indicating a relationship between the steering torque and the current target value that are predetermined to stop the application of the steering assist force Only when the steering torque detected by the torque sensor and the target value of the current set by the target value setting means match the selected drive prohibition condition. Drive inhibition means for stopping application of the steering assist force.

According to a second invention, in the first invention,
The drive prohibiting means includes a predetermined first drive prohibition condition and a second drive prohibition condition in which a wider range of conditions than the first drive prohibition condition is set, and the vehicle speed is equal to or higher than a predetermined vehicle speed threshold. The second drive prohibition condition is selected when the absolute value of the current detected by the motor current detection means is equal to or less than a predetermined current threshold value near 0, and whether the vehicle speed is less than the vehicle speed threshold value Alternatively, the first drive prohibition condition is selected when the absolute value of the current detected by the motor current detection means is larger than the current threshold value.

  According to the first aspect of the present invention, among the plurality of drive prohibition conditions, the drive prohibition condition according to the case where it is preferable to stop the steering assist is appropriately selected based on the vehicle speed and the current detected by the motor current detection means. Thus, it is possible to perform control to stop the steering assist quickly and surely.

  According to the second aspect of the invention, a wide range of conditions can be obtained when the vehicle speed is equal to or higher than a predetermined vehicle speed threshold and the absolute value of the current detected by the motor current detecting means is equal to or lower than the predetermined current threshold near zero. Since the second driving prohibition condition to be set is selected, if the hunting state is easily reached when the vehicle speed is high, the driving prohibition condition is likely to be met, and it is preferable to stop the steering assist quickly. It is possible to perform control to stop.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
<1. Overall configuration>
FIG. 1 is a schematic diagram showing a configuration of an electric power steering apparatus according to an embodiment of the present invention, together with a vehicle configuration related thereto. This electric power steering apparatus includes a steering shaft 102 whose one end is fixed to a handle 100 as an operation means for steering, a rack and pinion mechanism 104 connected to the other end of the steering shaft 102, and an operation of the handle 100. A torque sensor 3 for detecting a steering torque T applied to the steering shaft 102, a vehicle speed sensor 4 for detecting a traveling speed V of the vehicle, and a motor for generating a steering assist force for reducing a driver's load caused by a steering operation. 6, a reduction gear 7 that transmits a steering assist force generated by the motor 6 to the steering shaft 102, and a power supply from the in-vehicle battery 8, and the motor 6 based on sensor signals from the torque sensor 3 and the vehicle speed sensor 4. And an electronic control unit (ECU) 5 for controlling the drive of the To have.

  When the driver operates the handle 100, the motor 5 is driven by the ECU 5 based on the steering torque T detected by the torque sensor 3 and the vehicle speed V detected by the vehicle speed sensor 4. As a result, the motor 6 generates a steering assist force, and this steering assist force is applied to the steering shaft 102 via the reduction gear 7, thereby reducing the driver's load due to the steering operation. That is, the sum of the steering torque applied by the steering operation and the torque by the steering assist force generated by the motor 6 is given to the rack and pinion mechanism 104 via the steering shaft 102 as the output torque. Thus, when the pinion shaft rotates, the rotation is converted into a reciprocating motion of the rack shaft by the rack and pinion mechanism 104. Both ends of the rack shaft are connected to a wheel 108 via a connecting member 106 composed of a tie rod and a knuckle arm, and the direction of the wheel 108 changes according to the reciprocating motion of the rack shaft.

<2. Configuration and operation of control device>
FIG. 2 is a block diagram showing a functional configuration of the ECU 5, which is a control device in the electric power steering apparatus. The ECU 5 generates a microcomputer (hereinafter abbreviated as “microcomputer”) 10 functioning as a motor control unit, and a pulse width modulation signal (PWM signal) having a duty ratio corresponding to a command value D output from the microcomputer 10. The PWM signal generation circuit 18 that performs this operation, the motor drive circuit 20 that applies a voltage corresponding to the duty ratio of the PWM signal to the motor 6, and the current detector 19 that detects the current flowing through the motor 6.

  The microcomputer 10 executes a predetermined program stored in its internal memory, whereby a target current setting / determination unit 12, a subtractor 14, and a feedback control calculation unit (hereinafter abbreviated as "FB control calculation unit") 16 It functions as a motor control unit consisting of In this motor control unit, the target current setting / determination unit 12 compares the detected value T of the steering torque output from the torque sensor 3 (hereinafter simply referred to as “steering torque T”) and the vehicle speed output from the vehicle speed sensor 4. Based on the detected value V (hereinafter simply referred to as “vehicle speed V”), a target value It of current to be supplied to the motor 6 is determined. The detailed configuration and operation of the target current setting / determination unit 12 will be described later. The subtractor 14 calculates a deviation (It−Is) between the target current value It output from the target current setting / determination unit 12 and the detected value Is of the motor current output from the current detector 19. The FB control calculation unit 16 generates the command value D for feedback control to be given to the PWM signal generation circuit 18 by proportional-integral control calculation based on this deviation (It-Is).

  The PWM signal generation circuit 18 generates a pulse signal having a duty ratio corresponding to the command value D, that is, a PWM signal whose pulse width changes according to the command value D. The motor drive circuit 20 is typically a bridge circuit composed of four power field-effect transistors connected between the power supply line and the ground line of the battery 8, and is a pulse width (duty duty) of the PWM signal. A voltage corresponding to the ratio is applied to the motor 6. When the motor drive circuit 20 receives a drive inhibition signal Ss described later from the target current setting / determination unit 12, the motor drive circuit 20 stops driving the motor 6. The motor 6 generates a torque having a magnitude and direction corresponding to the current that flows when the voltage is applied. As described above, the subtractor 14 that receives the current target value It, the FB control calculation unit 16, the PWM signal generation circuit 18, the motor drive circuit 20, and the current detector 19 that outputs the detected value Is of the motor current to the subtractor 14 are provided. The control means for performing feedback control on the motor 6 is configured.

  Although the electric motor 6 is a general DC motor with a brush, the electric motor as a drive source in the present invention is not limited to the brush motor, and may be a brushless motor, for example. .

<3. Detailed configuration and operation of target current setting / determination unit>
FIG. 3 is a block diagram illustrating a configuration of the target current setting / determination unit 12 in the embodiment. This target current setting / determination unit 12 and a target current determination unit 12a for setting a current target value It and a target current determination for performing a drive prohibition determination as to whether or not to stop steering assist (operation for applying steering assist force). Part 12b. The target current setting unit 12a includes an assist map 122 indicating a correspondence relationship between the current target value It and the steering torque T, and an assist current setting unit 121 that outputs the current target value It by referring to the assist map 122. . The target current determination unit 12b determines whether or not to stop the steering assist based on the drive prohibition map 124 including a condition for stopping the steering assist as a predetermined drive prohibition region, the current target value It, and the steering torque T. Driving prohibition determination unit 123.

  The steering torque T may be phase-compensated by passing it through a phase compensator (not shown) comprising a phase advance filter having a predetermined parameter. Various compensations such as inertia compensation and damping control may be performed on the current target value It. In this case, the current target value subjected to various compensations is handled as the following current target value It. Since these configurations are known, detailed description thereof is omitted. The operation of each component in the target current setting / determination unit 12 will be described below.

  FIG. 4 is a diagram showing an example of the assist map. The assist map 122 shown in FIG. 4 is a table showing the relationship between the current target value It to be supplied to the motor 6 and the steering torque T in order to generate an appropriate steering assist force, with the vehicle speed V as a parameter, and a predetermined storage. Pre-held in the area. The assist map 122 is set so that the absolute value of the current target value It is increased as the vehicle speed V is smaller and the absolute value of the steering torque T is larger. By doing so, the steering assist force becomes larger as the handle becomes heavier, and the steering operation becomes easier. As shown in FIG. 4, the assist map 122 has a so-called dead zone in which the current target value It is 0 when the absolute value of the steering torque T is small enough not to require steering assistance. Have.

  The assist current setting unit 121 refers to the assist map 122 and outputs a corresponding current target value It based on the steering torque T received from the torque sensor 3 and the vehicle speed V received from the vehicle speed sensor 4.

  FIG. 5 is a diagram showing a drive prohibition map in which the drive prohibition area is indicated by hatching. More specifically, FIG. 5A shows a case where the vehicle speed is relatively large and the absolute value of the detected value of the motor current is relatively small. FIG. 5B is a diagram showing a drive prohibition map selected when the vehicle speed is relatively small or the absolute value of the detected value of the motor current is relatively large. . FIG. 5 also shows the assist map 122 shown in FIG. 4 in order to clarify the correspondence between the drive prohibition map 124 and the assist map 122.

  These drive prohibition maps 124 are tables showing the drive prohibition conditions, which are conditions for stopping steering assistance, as the relationship between the current target value It to be supplied to the motor 6 and the steering torque T, and these are predetermined storages. Pre-held in the area. The drive prohibition map 124 (hereinafter also referred to as “drive prohibition map A”) shown in FIG. 5A does not match the correspondence between the current target value It and the steering torque T indicated by the assist map 122 (that is, this correspondence). Since the position on the drive prohibition map A corresponding to the relationship is not included in the drive prohibition region), the current target value It output from the assist current setting unit 121 and the torque sensor 3 are output as long as the apparatus operates normally. The steering torque T does not match the condition indicated in the drive prohibition region. However, when the apparatus operates abnormally, the steering assist force decreases when the vehicle speed is high due to the characteristics of the assist map. Therefore, driving prohibition corresponding to the correspondence between the current target value It and the steering torque T is possible even in the hunting state. Even when the position on the map A is not included in the above-described drive prohibition region, that is, the state where it does not easily match the drive prohibition condition and it is preferable to stop the steering assist, the control to stop the steering assist is performed. There is a possibility not to be broken.

  In contrast, the drive prohibition map 124 (hereinafter also referred to as “drive prohibition map B”) shown in FIG. 5B is wider than the drive prohibition map 124 shown in FIG. Since the drive prohibition conditions are more severe, when the vehicle is in a hunting state when the vehicle speed is high, the position on the drive prohibition map B corresponding to the correspondence relationship between the current target value It and the steering torque T is within the drive prohibition region. When it is easy to be in an included state, that is, a state that matches the driving prohibition condition and it is preferable to stop the steering assist, it is possible to quickly perform the control to stop the steering assist.

Here, as shown in FIG. 5B, the drive prohibition map B partially matches the correspondence between the current target value It and the steering torque T indicated by the assist map 122 (that is, the current target value It. Since the position on the drive prohibition map B corresponding to the correspondence relationship between the steering torque T and the steering torque T is included in the drive prohibition area), the drive prohibition map B cannot always be used. If used, the steering assistance may be stopped even though the steering assistance is necessary. Therefore, any one of these drive prohibition maps 124 must be appropriately selected by the drive prohibition determination unit 123.

  Therefore, the drive prohibition determination unit 123 uses the two drive prohibition maps A and B shown in FIG. 5 based on the detected value Is of the motor current detected by the current detector 19 and the vehicle speed V detected by the vehicle speed sensor 4. One of them is selected as appropriate. Furthermore, the drive prohibition determination unit 123 determines that the current target value It output from the assist current setting unit 121 and the steering torque T output from the torque sensor 3 match the conditions indicated in the selected drive prohibition map. In this case, the motor 6 (steering assist) is controlled to stop by giving a predetermined drive prohibition signal Ss to the motor drive circuit 20. When the motor drive circuit 20 receives the drive prohibition signal Ss from the drive prohibition determination unit 123, the motor drive circuit 20 performs an operation that does not apply a voltage to the motor 6 (does not energize) or an operation that sets the voltage of a signal applied to the motor 6 to zero. Therefore, the drive prohibition determination unit 123, the drive prohibition map 124, and the motor drive circuit 20 function as a drive prohibition unit. Hereinafter, the operation of the drive prohibition determination unit 123 that realizes this function will be described in detail.

<4. Operation of Drive Prohibition Determination Unit>
FIG. 6 is a flowchart showing a procedure of the determination operation and the control operation in the drive prohibition determination unit 123. First, the drive prohibition determination unit 123 receives the detected value Is of the motor current detected by the current detector 19 and the vehicle speed V detected by the vehicle speed sensor 4 (step S10).

  Next, the drive prohibition determination unit 123 determines whether the vehicle speed V received in step S10 is high and the absolute value of the detected value Is of the motor current is small (hereinafter, this state is referred to as “high speed / low output state”). It is determined whether or not (step S20). Specifically, the vehicle speed V is equal to or higher than a predetermined vehicle speed threshold (for example, 80 Km / h) larger than the average normal traveling speed of a general vehicle, and the absolute value of the detected value Is of the motor current is an assist operation. If the current value is smaller than a predetermined current threshold value (for example, a predetermined value near 0) smaller than the absolute value of the normal current detection value at that time, it is determined that the state is a high-speed / low-output state. As a result of the determination, if it is in the high speed / low output state (Yes in step S20), the drive prohibition map B shown in FIG. 5B is selected (step S30), and the process proceeds to step S50. If the result of determination is that the vehicle is not in a high speed / low output state (No in step S20), the drive inhibition map A shown in FIG. 5A is selected (step S40), and the process proceeds to step S50.

  As described above, when not in the high speed / low output state, the normal driving prohibition map A (which basically does not match the correspondence between the current target value It and the steering torque T indicated by the assist map 122) is used. In the low output state, the drive prohibition map B including the drive prohibition area wider than the drive prohibition area included in the drive prohibition map A (and therefore, the drive prohibition conditions are stricter) is used. As a result, when the hunting state is entered when the vehicle speed is high, a position on the drive prohibition map B corresponding to the correspondence relationship between the current target value It and the steering torque T is included in the drive prohibition region, that is, a drive prohibition condition. When the steering assist is preferably stopped, control for quickly stopping the steering assist is performed.

  Subsequently, in step S <b> 50, the drive prohibition determination unit 123 receives the current target value It output from the assist current setting unit 121 and the steering torque T output from the torque sensor 3.

  Further, the drive prohibition determination unit 123 determines whether the position in the drive prohibition map corresponding to the current target value It and the steering torque T received in step S50 is the drive prohibition map A or the drive prohibition map selected in step S30 or step S40. It is determined whether it is included in the drive prohibition area included in B, that is, whether the drive prohibition condition is met (step S60). As a result of the determination, if the drive prohibition condition is not met (No in step S60), the process returns to step S10, and the above process is repeated until the apparatus is stopped or the drive condition is met (S60 → S10 → S20 → ... → S60).

  If the result of determination in step S60 is that the drive prohibition condition is met (Yes in step S60), the drive prohibition determination unit 123 stops the motor 6 by providing the motor drive circuit 20 with the drive prohibition signal Ss. Control is performed (step S70). If the drive prohibition condition is met, there is a possibility that an abnormality has occurred in the device such as the current detector 19, and a warning to that effect may be displayed to the driver. Thereafter, the drive prohibition determination unit 123 ends the process once, and starts the process again when a predetermined condition such as a reset operation by the driver is satisfied.

  As described above, in the present embodiment, the microcomputer 10 executes a predetermined program so that various components in the target current setting / determination unit 12 are realized as software. Some or all of the components may be realized in hardware by a dedicated electronic circuit or the like.

<5. Modification>
In step S20 (and S30) in the above-described embodiment, the driving prohibition map B having severe driving prohibition conditions is selected in the high speed and low output state. However, if the abnormal state of the apparatus can be detected more quickly, the speed is not necessarily high. It is not necessary to be based on the determination of whether or not it is in a low output state. For example, the drive prohibition map B may be selected when a value obtained by dividing the detected value Is of the motor current by the vehicle speed V is equal to or less than a predetermined threshold value X.

  Although there are two drive prohibition maps 124 (included in the target current setting / determination unit 12) in the above-described embodiment, there may be three or more. In that case, the drive prohibition determination unit 123 appropriately selects one of the drive prohibition maps 124 according to the relationship between the vehicle speed V and the absolute value of the detected value Is of the motor current. For example, when the vehicle speed is very high (for example, 100 km / h or more), a drive prohibition map including a drive prohibition area wider than the drive prohibition map B (stricter drive prohibition conditions) is selected. To do. Further, while the two drive prohibition maps 124 are the same as in the above-described embodiment, the drive prohibition determination unit 123 is used when a transition is made from the high speed / low output state to the non-high speed / low output state or in the opposite direction. In accordance with the relationship between the vehicle speed V and the absolute value of the detected value Is of the motor current, an intermediate value between these two drive prohibition maps 124 is continuously (or stepwise) set as a new drive prohibition region. In other words, it may be configured to gradually switch from the drive prohibition map B to the drive prohibition map A or in the opposite direction through the drive prohibition area calculated in this way.

  In addition, the drive prohibition map 124 in the above-described embodiment has a shape in which a plurality of rectangular drive prohibition regions are combined. However, the shape is not limited as long as the abnormal state of the apparatus can be detected. For example, in the drive prohibition map B, the absolute value of the current target value It is relatively small and the absolute value of the steering torque T is not very large (for example, 1 to 2N), typically in the vicinity of the dead zone in the assist map 122 The drive prohibition map may be such that only the drive prohibition area corresponding to this area is wider than the drive prohibition area of the drive prohibition map A (the drive prohibition condition is made stricter).

  Further, the assist map 122 or the drive prohibition map 124 (included in the target current setting / determination unit 12) in the above-described embodiment may be appropriately selected from among a plurality prepared in advance according to the travel mode and the like. . Further, instead of the assist map 122 or the drive prohibition map 124, a predetermined conditional expression or function expression may be referred to.

  In the above-described embodiment, the drive prohibition determination unit 123 applies the drive prohibition signal Ss to the motor drive circuit 20, thereby reducing the voltage of the signal applied to the motor 6 or the operation that does not apply voltage to the motor 6 (does not energize). However, for example, by providing the PWM signal generation circuit 18 with the drive inhibition signal Ss, the operation for setting the command value D for feedback control to 0 may be performed. Good. Alternatively, the PWM signal generation circuit 18 may be provided with a drive inhibition signal Ss so that the duty ratio of the PWM signal transmitted to the motor drive circuit 20 is set to 0% and output. Further, control may be performed so that the operation of physically stopping or blocking the application of the steering assist force by the motor 6 is performed.

<6. Effect>
As described above, according to the above-described embodiment, the vehicle speed is reduced by using the drive prohibition map including the drive prohibition area that is relatively wide (the drive prohibition condition is stricter) in the high speed / low output state. When the hunting state is established when the value is large, the position on the drive prohibition map A corresponding to the correspondence between the current target value It and the steering torque T is included in the drive prohibition region, that is, the drive prohibition condition is met. Since it becomes easy, control which stops steering assistance quickly and reliably can be performed. Hereinafter, it will be specifically described that the steering assist can be stopped early when necessary.

  FIG. 7 is a diagram illustrating a temporal change of a current target value or the like when a failure occurs in the current detector and a timing when the drive prohibiting operation is performed. As shown in FIG. 7, when a failure occurs in the current detector 19 at time t1, the current detection value Is is 0 and constant. The same applies to whether the current detector 19 is normal or the microcomputer 10 is abnormal. Here, a case where the current detection value Is is constant at an abnormally large value other than 0 may be considered. In such a case, the motor 6 immediately generates an abnormally large torque in accordance with the value of the current detection value Is (the command value D increases), so that an abnormal state is relatively easy to detect. However, when the current detection value Is is constant at a value close to 0, since the torque fluctuation of the motor 6 is small, an abnormal state is difficult to detect and the advantage of the present invention is great. Therefore, here, the current detection value Is is assumed to be constant at 0.

  First, at the time when not much time has elapsed since time t1, the influence of the abnormality of the current detection value Is is not significant, but the input torque to the driver's handle 100 does not change much as time passes. Nevertheless, changes in the steering torque detection value T and the current target value It are gradually increasing. This is because when the driver performs an operation of fixing the steering wheel 100 in resistance to steering assistance in an incorrect direction and amount due to an abnormality in the detected current value Is, the torque of the motor 6 is applied to the steering wheel 100 of the driver. This is because the steering torque is erroneously detected as a result of the operation, resulting in a hunting state. This hunting state becomes violent with time, and as shown in FIG. 7, when a relatively gentle driving prohibition map A with a driving prohibition condition is used, the correspondence relationship between the current target value It (and the steering torque T) at time t3. In the drive prohibition area of the drive prohibition map A and an abnormality is detected (drive prohibition operation is performed), but when the drive prohibition map B having relatively severe drive prohibition conditions is used, the time At time t2 earlier than t3, the current target value It (and a position corresponding to the correspondence relationship of the steering torque T) is included in the drive prohibition region of the drive prohibition map B, and an abnormality is detected (drive prohibition operation is performed). As described above, by using the drive prohibition map B including a relatively wide drive prohibition region (stricter drive prohibition conditions) in the high speed / low output state, the control for quickly and reliably stopping the steering assist is performed. be able to.

It is the schematic which shows the structure of the electric power steering apparatus which concerns on one Embodiment of this invention with the vehicle structure relevant to it. It is a block diagram which shows the functional structure of ECU which is a control apparatus in the electric power steering apparatus which concerns on the said one Embodiment. It is a block diagram which shows the structure of the target electric current setting and determination part in the said one Embodiment. It is a figure which shows the example of the assist map in the said one Embodiment. It is a figure which shows the drive prohibition map which showed the drive prohibition area | region in the said one Embodiment by the oblique line. It is a flowchart which shows the determination procedure of the drive prohibition determination part in the said one Embodiment. In the said one Embodiment, it is a figure which shows a time change, such as a current target value when a failure generate | occur | produces in a current detector, and the time when drive prohibition operation | movement is performed.

Explanation of symbols

3 ... Torque sensor 4 ... Vehicle speed sensor 5 ... Electronic control unit (ECU)
6 ... Motor 10 ... Microcomputer 12 ... Target current setting / determination unit 14 ... Subtractor 16 ... Feedback control calculation unit (FB control calculation unit)
DESCRIPTION OF SYMBOLS 18 ... PWM signal generation circuit 19 ... Current detector 20 ... Motor drive circuit 121 ... Assist current setting part 122 ... Assist map 123 ... Drive prohibition determination part 124 ... Drive prohibition map It ... Current target value T ... Steering torque V ... Vehicle speed Ss ... Drive prohibition signal

Claims (2)

  1. An electric power steering device that applies a steering assist force to a steering mechanism of a vehicle by driving an electric motor in accordance with a steering torque applied by an operation means for vehicle steering,
    A vehicle speed sensor for detecting the traveling speed of the vehicle as a vehicle speed;
    A torque sensor for detecting the steering torque;
    Motor current detecting means for detecting a current flowing through the electric motor;
    Target value setting means for setting a target value of a current to be supplied to the electric motor in order to give the steering assist force based on the steering torque detected by the torque sensor;
    Control means for controlling the electric motor based on the target value of the current;
    Based on the vehicle speed and the current detected by the motor current detecting means, a plurality of drive prohibiting conditions indicating a relationship between the steering torque and the current target value that are predetermined to stop the application of the steering assist force Only when the steering torque detected by the torque sensor and the target value of the current set by the target value setting means match the selected drive prohibition condition. An electric power steering apparatus comprising: drive prohibiting means for stopping application of steering assist force.
  2.   The drive prohibiting means includes a predetermined first drive prohibition condition and a second drive prohibition condition in which a wider range of conditions than the first drive prohibition condition is set, and the vehicle speed is equal to or higher than a predetermined vehicle speed threshold. The second drive prohibition condition is selected when the absolute value of the current detected by the motor current detection means is equal to or less than a predetermined current threshold value near 0, and whether the vehicle speed is less than the vehicle speed threshold value 2. The electric power steering according to claim 1, wherein the first drive prohibition condition is selected when an absolute value of a current detected by the motor current detection unit is larger than the current threshold value. 3. apparatus.
JP2004236697A 2004-08-16 2004-08-16 Electric power steering device Pending JP2006051912A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2004236697A JP2006051912A (en) 2004-08-16 2004-08-16 Electric power steering device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2004236697A JP2006051912A (en) 2004-08-16 2004-08-16 Electric power steering device

Publications (1)

Publication Number Publication Date
JP2006051912A true JP2006051912A (en) 2006-02-23

Family

ID=36029656

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2004236697A Pending JP2006051912A (en) 2004-08-16 2004-08-16 Electric power steering device

Country Status (1)

Country Link
JP (1) JP2006051912A (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008238843A (en) * 2007-03-26 2008-10-09 Showa Corp Electric power steering device
JP2010158938A (en) * 2009-01-07 2010-07-22 Honda Motor Co Ltd Electric power steering device
JP2011183923A (en) * 2010-03-08 2011-09-22 Hitachi Automotive Systems Ltd Electric power steering control device and electric power steering system
WO2015052897A1 (en) * 2013-10-10 2015-04-16 日本精工株式会社 Electric power steering device
US9037351B2 (en) 2013-01-17 2015-05-19 Omron Automotive Electronics Co., Ltd. Steering control device
JP5817938B2 (en) * 2013-03-27 2015-11-18 日本精工株式会社 Electric power steering device

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008238843A (en) * 2007-03-26 2008-10-09 Showa Corp Electric power steering device
JP2010158938A (en) * 2009-01-07 2010-07-22 Honda Motor Co Ltd Electric power steering device
JP4728406B2 (en) * 2009-01-07 2011-07-20 本田技研工業株式会社 Electric power steering device
JP2011183923A (en) * 2010-03-08 2011-09-22 Hitachi Automotive Systems Ltd Electric power steering control device and electric power steering system
US9037351B2 (en) 2013-01-17 2015-05-19 Omron Automotive Electronics Co., Ltd. Steering control device
JP5817938B2 (en) * 2013-03-27 2015-11-18 日本精工株式会社 Electric power steering device
WO2015052897A1 (en) * 2013-10-10 2015-04-16 日本精工株式会社 Electric power steering device
CN105473420A (en) * 2013-10-10 2016-04-06 日本精工株式会社 Electric power steering device
US9352770B2 (en) 2013-10-10 2016-05-31 Nsk Ltd. Electric power steering apparatus
JP5971427B2 (en) * 2013-10-10 2016-08-17 日本精工株式会社 Electric power steering device

Similar Documents

Publication Publication Date Title
EP2842838B1 (en) Electric power steering system
US8660755B2 (en) Electric power steering system
US6070692A (en) Electric power steering control system
US6987371B2 (en) Steering controlling device
WO2014203300A1 (en) Motor control device, and electric power steering device and a vehicle which use same
US8280589B2 (en) Steering apparatus
JP3479730B2 (en) Electric power steering device
US6838846B2 (en) Electric power steering apparatus
US8781682B2 (en) Electric power steering system
EP1984229B1 (en) Electric power steering device, and control method thereof
US7523806B2 (en) Method and system for improved active damping of steering systems
US5404960A (en) Motor-driven power steering apparatus for automobiles
US6439336B2 (en) Electric power steering apparatus
JP2998929B2 (en) Electric power steering device
US6326753B1 (en) Controller of electric power-steering system
DE19837665B4 (en) Electric power steering device
JP4806941B2 (en) Power steering control device
US20140180544A1 (en) Electric power steering system
US9787240B2 (en) Controller and control method for motor
JP6053651B2 (en) Power steering device and control device for on-vehicle equipment
US8989965B2 (en) Electric power steering apparatus
US9358925B2 (en) Warning device for vehicle
US6883637B2 (en) Electric power steering device and control method utilized for controlling said electric power steering device
DE19742370B4 (en) Control of an electric power steering system
US10214235B2 (en) Power steering device and power steering device control unit

Legal Events

Date Code Title Description
A711 Notification of change in applicant

Free format text: JAPANESE INTERMEDIATE CODE: A712

Effective date: 20060523

A711 Notification of change in applicant

Free format text: JAPANESE INTERMEDIATE CODE: A711

Effective date: 20060811