JP5050539B2 - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device capable of suppressing the generation of gear rattling noise when applying inversely input stress. <P>SOLUTION: A motor 21 as a drive source of an EPS actuator 22 is connected to a column shaft via a reduction gear mechanism engaged with a reduction gear provided at the column shaft and a motor gear provided at a motor shaft. An ECU 23 detects the rotational angular velocity of the reduction gear (the pinion angular velocity &omega;ap) as a first angular velocity, and a second angular velocity (the converted pinion angular velocity &omega;p_cnv) which converts the rotational angular velocity of the motor gear into the rotational angular velocity of the reduction gear. The differential value (the angular velocity &Delta;&omega;p) between the first angular velocity and the second angular velocity is calculated, and when the differential value (the absolute value of the differential angular velocity &Delta;&omega;p) exceeds a predetermined threshold, the operation of the EPS actuator 22 is controlled so as to reduce an assist force to be given to a steering system. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an electric power steering apparatus.

2. Description of the Related Art Conventionally, some electric power steering devices (EPS) using a motor as a drive source apply a motor torque as an assist force to a steering system by rotationally driving a steering shaft. Usually, in such EPS, the motor is connected to the steering shaft via a speed reduction mechanism (for example, a worm and wheel) formed by meshing the first and second gears. The rotation of the motor is decelerated by the speed reduction mechanism and transmitted to the steering shaft (see, for example, Patent Document 1).
JP 2004-291718 A

  By the way, the EPS uses a torque sensor 73 for detecting a steering torque based on a torsion angle of a torsion bar 72 provided in the middle of a steering transmission system (steering shaft 71) connecting a steering wheel and a steered wheel as shown in FIG. I have. FIG. 16 shows what is widely used as an EPS torque sensor, that is, a so-called torsion angle of the torsion bar 72 detected by a pair of angle sensors 74 a and 74 b (resolvers) provided at both ends of the torsion bar 72. It is a schematic diagram which shows schematic structure of a twin resolver type | mold torque sensor. Based on the steering torque detected by the torque sensor, an assist force is applied in a direction to reduce the steering reaction force.

  However, in the EPS in which the motor and the steering shaft are drivingly connected via the speed reduction mechanism that meshes the first and second gears as described above, the motor rotates to reduce the steering reaction force as described above. By doing so, there is a possibility that rattling noise (rattle noise) may be generated at the meshing portions of both gears constituting the speed reduction mechanism.

  That is, for example, when reverse input stress is applied to the steered wheels when traveling on an irregular road surface, the steering shaft rotates based on the reverse input stress. At this time, in the torque sensor provided on the steering shaft, torque based on the reverse input stress is detected as a steering reaction force. Then, the motor rotates in order to apply an assist force in a direction to reduce (cancel) the steering reaction force.

  That is, as shown in FIG. 17, when such reverse input stress is applied, the first gear (reduction gear) 75 that rotates integrally with the steering shaft, and the second gear (motor gear) 76 that rotates by driving the motor, Will rotate in opposite directions, and as a result, the teeth 75a and 76a engaged with each other will collide with each other. Furthermore, the reverse input stress applied to the steered wheels remains in the steering system as vibration. For this reason, each of the first and second gears 75 and 76 repeats the collision as described above while reversing the rotation direction, and the impact may be transmitted to the outside as a rattling sound. is there.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an electric power steering device capable of suppressing the occurrence of rattling noise when reverse input stress is applied. .

In order to solve the above-described problems, the invention according to claim 1 is a steering force assisting device that applies an assist force for assisting a steering operation to a steering system by rotationally driving a steering shaft using a motor as a drive source. And control means for controlling the operation of the steering force assisting device through supply of driving power to the motor, the motor via the speed reduction mechanism formed by meshing the first and second gears. An electric power steering device drivingly connected to a shaft, wherein the first angular velocity detecting means detects the rotational angular velocity of the first gear as a first angular velocity, and the rotational angular velocity of the second gear is the first angular velocity. of a second angular velocity detecting means for detecting a second angular velocity in terms of the rotational angular velocity of the gear, said control means, said first and second of said detected Calculates the difference value of the speed, when the absolute value of said difference value exceeds a predetermined threshold, to the control in order to reduce the assist force, and the gist.

  That is, the rattling noise in the speed reduction mechanism is generated by the collision between the first gear (the teeth) and the second gear (the teeth). When reverse input stress is applied, the first gear and the second gear rotate at high speeds in opposite directions, that is, repeatedly collide with a large rotational angular velocity difference between them, generating a large rattling noise. To do.

  In this regard, as in the above configuration, when a value corresponding to the application of reverse input stress is detected as the difference value between the first and second angular velocities, the assist force applied to the steering system is reduced. For example, it is possible to suppress the rotational angular velocity when the gear on the side rotated by the motor among the first and second gears rotates in the opposite direction to the gear on the side rotating integrally with the steering shaft. Thereby, the rotation angular velocity difference at the time of both collision can be made small, As a result, generation | occurrence | production of the rattling sound in a deceleration mechanism can be suppressed effectively.

The gist of the invention described in claim 2 is that the control means performs the control to greatly reduce the assist force as the absolute value of the difference value is larger.
According to the above configuration, as the difference value (absolute value) between the first and second angular velocities at which the first gear and the second gear collide strongly is larger, the side that is rotationally driven by the motor. The rotational angular speed of the gear can be suppressed and the impact can be mitigated. As a result, generation of rattling noise can be more effectively suppressed.

The gist of the invention described in claim 3 is that the control means reduces the assist force only when the vehicle speed is in a predetermined vehicle speed region.
That is, the amplitude of the reverse input stress remaining as vibration in the steering system depends on the vibration characteristics of the suspension that supports the steered wheels, and is amplified in a predetermined vehicle speed region where resonance occurs in the suspension. The rattling noise generated in the speed reduction mechanism also tends to be particularly noticeable in this predetermined vehicle speed region. That is, paradoxically speaking, when the vehicle speed is not in the predetermined vehicle speed region, the rattling noise in the speed reduction mechanism is not particularly problematic. Accordingly, by reducing the assist force only when the vehicle speed is in a predetermined vehicle speed region as in the above configuration, the rattling sound is effectively generated in the speed reduction mechanism without impairing the steering feeling. Can be suppressed.

The gist of the invention of claim 4 is that the control means does not reduce the assist force when the absolute value of the steering angle is equal to or greater than a predetermined threshold.
The gist of the invention described in claim 5 is that the control means does not reduce the assist force when the absolute value of the steering speed is a predetermined threshold value or more.

The gist of the invention described in claim 6 is that the control means does not reduce the assist force when the absolute value of the steering torque is not less than a predetermined threshold value.
The gist of the invention described in claim 7 is that the control means does not reduce the assist force when the absolute value of the yaw rate of the vehicle is equal to or greater than a predetermined threshold value.

The gist of the invention described in claim 8 is that the control means does not reduce the assist force during vehicle braking.
As described above, when the vehicle is braked, priority is given to the application of assist force to the steering system, so that vibration transmitted to the steering system accompanying the braking can be dealt with. As a result, it is possible to effectively suppress the occurrence of rattling noise in the speed reduction mechanism without impairing the steering feeling.

The invention according to claim 9 is characterized in that the control means reduces the assist force by superimposing a compensation amount based on a difference value between the first and second angular velocities on a basic assist component. The gist.

The invention according to claim 1 0, wherein, the basic assist component, by multiplying the calculated the compensation gain based on the difference value of the first and second angular velocity, performing reduction of the assist force This is the gist.

According to each said structure, reduction of precise assist force can be performed.
The invention of claim 1 1, wherein the control means, the basic assist component, by superimposing a compensation amount based on the differential value of the steering torque, calculates a target assist force to be generated in the steering force assist device This is the gist.

That is, by executing compensation control based on the differential value of the steering torque, the phase of the first and second gears that are rotationally driven by the motor is shifted (90 ° advance). become. For this reason, in the case of executing the compensation control based on the differential value of the steering torque, the difference value (absolute value) between the first and second angular velocities tends to be large, and the rattling noise generated thereby becomes also remarkable. It tends to be easy. Thus, for those performing such compensation control, by applying the configuration of the claims 1 to 1 0, it is possible to obtain a more remarkable effect.

  ADVANTAGE OF THE INVENTION According to this invention, the electric power steering apparatus which can suppress generation | occurrence | production of the rattling sound at the time of reverse input stress application can be provided.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is embodied in a column-type electric power steering apparatus (EPS) will be described with reference to the drawings.

  As shown in FIG. 1, in the electric power steering apparatus (EPS) 1 of the present embodiment, a steering shaft 3 to which a steering 2 is fixed is connected to a rack shaft 5 via a rack and pinion mechanism 4, and the steering The rotation of the steering shaft 3 accompanying the operation is converted into a reciprocating linear motion of the rack shaft 5 by the rack and pinion mechanism 4. Specifically, the steering shaft 3 of the present embodiment is formed by connecting a column shaft 8, an intermediate shaft 9, and a pinion shaft 10 via universal joints 7a and 7b. The rack and pinion mechanism 4 includes: The pinion teeth 10a formed at one end of the pinion shaft 10 are engaged with the rack teeth 5a on the rack shaft 5 side. The reciprocating linear motion of the rack shaft 5 accompanying the rotation of the steering shaft 3 is transmitted to a knuckle (not shown) via tie rods 11 connected to both ends of the rack shaft 5, whereby the steered angle of the steered wheels 12. That is, the traveling direction of the vehicle is changed.

  The EPS 1 according to the present embodiment controls the operation of the EPS actuator 22 by providing an assist force for assisting the steering operation to the steering system by rotating the steering shaft 3 using the motor 21 as a drive source. ECU23 which performs.

More specifically, the EPS actuator 22 of the present embodiment is configured as a so-called column-type EPS actuator that applies assist force to the column shaft 8, and the motor 21 that is a drive source is connected to the column shaft via the speed reduction mechanism 24. 8 is drive-coupled. In this embodiment, the speed reduction mechanism 24 is configured by meshing a reduction gear 25 provided so as not to rotate relative to the column shaft 8 and a motor gear 26 provided so as not to rotate relative to the motor shaft 21a. Has been. In the present embodiment, the reduction gear 25 as a first gear worm wheel is used, the motor gear 26 as the second gear is used worm gear. That is, the speed reduction mechanism 24 of the present embodiment is configured by a so-called worm and wheel. The EPS actuator 22 as a steering force assisting device decelerates the rotation of the motor 21 that is a driving source by the speed reduction mechanism 24 and transmits it to the column shaft 8, thereby giving the motor torque as an assist force to the steering system. It is configured as follows.

  On the other hand, the ECU 23 as control means supplies driving power to the motor 21 that is a driving source of the EPS actuator 22. And it is comprised so that rotation of the motor 21, ie, the action | operation of the EPS actuator 22, may be controlled through the supply of the drive electric power.

  More specifically, the ECU 23 is connected to a torque sensor 31 provided on the column shaft 8. In this embodiment, the column shaft 8 is formed by connecting a first shaft 8 a on the steering 2 side and a second shaft 8 b on the intermediate shaft 9 (pinion shaft 10) side via a torsion bar 33. Yes. The torque sensor 31 includes a torsion bar 33 and a pair of angle sensors 34a and 34b (resolvers) provided at both ends of the torsion bar 33 (the end of the first shaft 8a and the end of the second shaft 8b). It is configured.

  That is, the torque sensor 31 of the present embodiment is configured as a twin resolver type torque sensor, similar to the torque sensor 73 shown in FIG. 16, and the ECU 23 rotates the first shaft 8a by the first angle sensor 34a. The angle (steering angle θs) is detected, and the rotation angle (pinion angle θp) of the second shaft 8b is detected by the second angle sensor 34b. Then, the steering torque τ is detected based on the difference between the rotation angles detected by the both angle sensors 34a and 34b, that is, the twist angle of the torsion bar 33.

  In the present embodiment, the ECU 23 receives the vehicle speed V detected by the vehicle speed sensor 35, the yaw rate γ detected by the yaw rate sensor 36, and the brake signal Sbk indicating the presence or absence of a brake operation. Then, the ECU 23 determines a target assist force to be applied to the steering system based on the vehicle state quantities detected by these sensors, and drives the motor 21 to generate the target assist force in the EPS actuator 22. Execute power supply.

Next, an aspect of assist control in the EPS of the present embodiment will be described.
As shown in FIG. 2, the ECU 23 includes a microcomputer 41 that outputs a motor control signal, and a drive circuit 42 that supplies drive power to the motor 21 that is a drive source of the EPS actuator 22 based on the motor control signal. Configured.

  In the present embodiment, the ECU 23 is connected with a current sensor 43 for detecting the actual current value I supplied to the motor 21 and a rotation angle sensor 44 (see FIG. 1) for detecting the motor rotation angle θm. ing. Then, the microcomputer 41 controls the drive circuit 42 based on each vehicle state quantity and the actual current value I of the motor 21 and the motor rotation angle θm detected based on the output signals of the current sensor 43 and the rotation angle sensor 44. A motor control signal to be output is generated.

  Each control block shown below is realized by a computer program executed by the microcomputer 41. Then, the microcomputer 41 detects each state quantity at a predetermined sampling period, and generates a motor control signal by executing each arithmetic processing shown in the following control blocks at every predetermined period.

  More specifically, the microcomputer 41 is calculated by a current command value calculation unit 45 that calculates a target value of assist force to be applied to the steering system, that is, a current command value Iq * corresponding to the target assist force, and a current command value calculation unit 45. And a motor control signal output unit 46 for outputting a motor control signal based on the current command value Iq *.

  The current command value calculation unit 45 of this embodiment includes a basic assist control unit 47 that calculates a basic assist control amount Ias *, which is a basic control component of the target assist force, and a differential value ( And a torque inertia compensation control unit 48 for calculating a torque inertia compensation amount Iti * based on the steering torque differential value dτ).

  In this embodiment, the steering torque τ and the vehicle speed V are input to the basic assist control unit 47. Then, based on the steering torque τ and the vehicle speed V, the basic assist control unit 47 calculates a larger basic assist control amount Ias * as the steering torque τ increases and the vehicle speed V decreases.

  On the other hand, in addition to the steering torque differential value dτ, the vehicle speed V is input to the torque inertia compensation control unit 48 of the present embodiment. The torque inertia compensation control unit 48 executes torque inertia compensation control based on these state quantities. “Torque inertia compensation control” is control that compensates for the effects of EPS inertia, such as motors and actuators, that is, “feeling of catching (following delay)” at the time of “start of cutting” and “end of cutting” in steering operation. This is a control for suppressing the “flow feeling (overshoot)” at the time.

  Specifically, as shown in FIG. 3, the torque inertia compensation control unit 48 of the present embodiment includes a map 48a in which the steering torque differential value dτ and the basic compensation amount εti are associated, the vehicle speed V, the interpolation coefficient A, and the like. Is associated with a map 48b. In the map 48a, the basic compensation amount εti is a value that increases the basic assist control amount Ias * (absolute value) calculated by the basic assist control unit 47 as the absolute value of the input steering torque differential value dτ increases. It is set to become. Further, in the map 48b, the interpolation coefficient A is set so as to increase as the vehicle speed V increases in the low vehicle speed region, and to decrease as the vehicle speed increases in the high vehicle speed region. Then, the torque inertia compensation controller 48 calculates the torque inertia compensation amount Iti * by multiplying the basic compensation amount εti and the interpolation coefficient A obtained by referring to these maps 48a and 48b.

  As shown in FIG. 2, the basic assist control amount Ias * calculated in the basic assist control unit 47 and the torque inertia compensation amount Iti * calculated in the torque inertia compensation control unit 48 are input to the adder 49. The current command value calculation unit 45 calculates the current command value Iq * as the target assist force by superimposing the torque inertia compensation amount Iti * on the basic assist control amount Ias * in the adder 49.

  The current command value Iq * output from the current command value calculation unit 45 is output to the motor control signal output unit 46 together with the actual current value I detected by the current sensor 43 and the motor rotation angle θm detected by the rotation angle sensor 44. Entered. The motor control signal output unit 46 calculates a motor control signal by executing feedback control so that the actual current value I follows the current command value Iq * corresponding to the target assist force.

  Specifically, in the present embodiment, a brushless motor that rotates by supplying three-phase (U, V, W) driving power is used as the motor 21. Then, the motor control signal output unit 46 converts the phase current values (Iu, Iv, Iw) of the motor 21 detected as the actual current value I into d, q axis current values in the d / q coordinate system (d / q The current feedback control is performed by performing conversion.

  That is, the current command value Iq * is input to the motor control signal output unit 46 as a q-axis current command value, and the motor control signal output unit 46 is based on the motor rotation angle θm detected by the rotation angle sensor 44. The value (Iu, Iv, Iw) is d / q converted. Further, the motor control signal output unit 46 calculates the d and q axis voltage command values based on the d and q axis current values and the q axis current command value. Then, the phase voltage command values (Vu *, Vv *, Vw *) are calculated by performing d / q inverse conversion on the d and q axis voltage command values, and a motor control signal is generated based on the phase voltage command values. To do.

  In the ECU 23 of the present embodiment, the microcomputer 41 outputs the motor control signal generated as described above to the drive circuit 42, and the drive circuit 42 supplies the three-phase drive power based on the motor control signal to the motor 21. Is configured to control the operation of the EPS actuator 22.

[Rattle noise suppression compensation control]
Next, an aspect of rattle noise (tooth rattling noise) suppression compensation control in the EPS of the present embodiment will be described.

  As described above, most of the so-called column type (pinion type) EPS that applies an assist force to the steering system by transmitting the motor torque to the steering shaft, that is, a reduction mechanism formed by meshing the first and second gears. The EPS in which the motor and the steering shaft are connected to each other has a problem that rattling noise is generated in the speed reduction mechanism when reverse input stress is applied.

  In consideration of this point, in the EPS 1 of the present embodiment, the ECU 23 detects the rotational angular velocities (converted angular velocities) of the reduction gear 25 as the first gear and the motor gear 26 as the second gear that constitute the speed reduction mechanism 24. And based on the rotation angular velocity difference, the rattle noise suppression compensation control for suppressing generation | occurrence | production of the rattling sound in the above deceleration mechanisms 24 is performed.

  Specifically, the ECU 23 detects the rotational angular velocity (pinion angular velocity ωp) of the reduction gear 25 that rotates together with the column shaft 8 as the first angular velocity, and on the other hand, the rotational angular velocity of the motor gear 26 that is rotationally driven by the motor 21. The second angular velocity (converted pinion angular velocity ωp_cnv) converted from the rotational angular velocity of the reduction gear 25 is detected. Then, a difference value (angular velocity Δωp) between the first and second angular velocities is calculated, and when the difference value (absolute value thereof) exceeds a predetermined threshold value, the assist force applied to the steering system is reduced. The operation of the EPS actuator 22 is controlled.

  That is, the rattling sound in the speed reduction mechanism 24 is generated when the reduction gear 25 (the teeth) as the first gear collides with the motor gear 26 (the teeth) as the second gear. When reverse input stress is applied, the reduction gear 25 and the motor gear 26 rotate at high speeds in opposite directions, that is, repeatedly collide with a large difference in rotational angular velocity between the two, thereby generating a large rattling noise.

  Focusing on this point, the ECU 23 of the present embodiment reduces the assist force applied to the steering system when the rotational angular velocity difference corresponding to the application of the reverse input stress is detected, so that the motor gear 26 is reduced to the reduction gear. The rotational angular velocity when rotating in the opposite direction to 25 is suppressed. And it is comprised so that generation | occurrence | production of a rattling sound may be suppressed by making small the rotational angular velocity difference at the time of both colliding.

  More specifically, as shown in FIG. 2, the microcomputer 41 is detected by an angle sensor 34b constituting the torque sensor 31 (among the angle sensors 34a and 34b, the one provided on the second shaft 8b, see FIG. 1). The pinion angular velocity ωp, that is, the rotational angular velocity of the reduction gear 25 that rotates integrally with the second shaft 8b is detected by differentiating the pinion angle θp.

  Further, the microcomputer 41 determines the rotation angle of the motor gear 26 based on the motor rotation angle θm detected by the rotation angle sensor 44, that is, the rotation angle of the motor gear 26 provided on the motor shaft 21a, That is, the converted pinion angle θp_cnv converted to the pinion angle θp is calculated. The microcomputer 41 of this embodiment is provided with a rotation angle conversion unit 44a, and the motor rotation angle θm (electrical angle) detected by the rotation angle sensor 44 is converted into a converted pinion in the rotation angle conversion unit 44a. Converted to angle θp_cnv. The microcomputer 41 differentiates the converted pinion angle θp_cnv to detect the rotational angular velocity of the motor gear 26 when converted into the rotational angular velocity of the reduction gear 25, that is, the converted pinion angular velocity ωp_cnv.

  The calculated pinion angular velocity ωp as the first angular velocity and the converted pinion angular velocity ωp_cnv as the second angular velocity are input to the subtractor 50. In the subtractor 50, the subtracter 50 subtracts the converted pinion angular velocity ωp_cnv from the pinion angular velocity ωp to calculate the difference value, that is, the angular velocity difference value Δωp.

  Further, in the present embodiment, the current command value calculation unit 45 is provided with a rattle sound suppression compensation calculation unit 51, and the angular velocity difference value Δωp calculated by the subtractor 50 is the rattle sound suppression compensation calculation unit. 51 is input. The rattle noise suppression compensation calculation unit 51 then calculates the current command value Iq * (absolute value) output by the current command value calculation unit 45 in a region where the absolute value of the input angular velocity difference value Δωp exceeds a predetermined threshold. The rattle noise suppression compensation amount Ira * is calculated so that the assist force generated by the EPS actuator 22 is reduced.

  The rattle noise suppression compensation amount Ira * calculated in the rattle noise suppression compensation amount Ira * is the basic assist control amount Ias * output by the basic assist control unit 47 (and the torque inertia compensation amount Iti output by the torque inertia compensation control unit 48). *) And input to the adder 49. Then, the current command value calculation unit 45 sets a value obtained by superimposing the rattle noise suppression compensation amount Ira * on the basic assist control amount Ias * (and the torque inertia compensation amount Iti *) in the adder 49 as the current command value Iq *. This is output to the motor control signal output unit 46, whereby the assist force generated by the EPS actuator 22 is reduced.

Next, the configuration of the rattle noise suppression compensation calculation unit will be described.
As shown in FIG. 4, the rattle noise suppression compensation calculation unit 51 of the present embodiment calculates a basic compensation amount εra that is a basic component of the rattle noise suppression compensation amount Ira * based on the angular velocity difference value Δωp. A calculation unit 52 is provided. As shown in FIG. 5, the basic compensation amount calculation unit 52 includes a map 52a in which the angular velocity difference value Δωp and the basic compensation amount εra are associated with each other. The basic compensation amount calculation unit 52 calculates the basic compensation amount εra by referring to the input angular velocity difference value Δωp in the map 52a.

  More specifically, the map 52a is configured such that a predetermined basic compensation amount εra is calculated when the absolute value (| Δωp |) of the angular velocity difference value Δωp exceeds a predetermined threshold value α1. Specifically, in the map 52a, the basic compensation amount εra is set to “0” when the absolute value (| Δωp |) of the angular velocity difference value Δωp is equal to or less than the threshold value α1. In the region where the absolute value (| Δωp |) of the angular velocity difference value Δωp exceeds the threshold α1, the absolute value (| εra |) of the angular velocity difference value Δωp increases as the absolute value (| Δωp |) of the angular velocity difference value Δωp increases. That is, the current command value Iq * (absolute value) output by the current command value calculation unit 45 is set to a value that greatly reduces.

  Thereby, the basic compensation amount calculation unit 52 of the present embodiment has an absolute value (| Δωp |) of the angular velocity difference value Δωp in a region where the absolute value (| Δωp |) of the angular velocity difference value Δωp exceeds the threshold value α1. The basic compensation amount .epsilon.ra is calculated so that the assist force applied to the steering system is greatly reduced as.

  Further, the rattle noise suppression compensation calculation unit 51 of the present embodiment includes a plurality of correction gain calculation units that calculate a correction gain based on the vehicle state quantity. Then, each of the correction gains calculated by the respective correction gain calculation units is multiplied by the basic compensation amount εra to calculate a rattle noise suppression compensation amount Ira * corresponding to the vehicle state.

  Specifically, the rattle noise suppression compensation calculation unit 51 includes a vehicle speed gain calculation unit 53 that calculates a vehicle speed gain Kv, a steering angle gain calculation unit 54 that calculates a steering angle gain Kθ, and a steering speed gain that calculates a steering speed gain Kω. A calculation unit 55, a torque gain calculation unit 56 for calculating the torque gain Kτ, and a yaw rate gain calculation unit 57 for calculating the yaw rate gain Kγ are provided. The correction gains calculated by the respective correction gain calculation units, that is, the vehicle speed gain Kv, the steering angle gain Kθ, the steering speed gain Kω, the torque gain Kτ, and the yaw rate gain Kγ are the basic compensation amount εra output by the basic compensation amount calculation unit 52. And input to the multiplier 58. These correction gains (Kθ, Kω, Kτ, Kγ) are multiplied by the basic compensation amount εra in the multiplier 58.

Next, the configuration of each correction gain and each correction gain calculation unit will be described.
The vehicle speed gain Kv is a correction gain for correcting the rattle noise suppression compensation amount Ira * according to the vehicle speed V. As shown in FIG. 6, the vehicle speed gain calculation unit 53 is provided with a map 53a in which the vehicle speed V and the vehicle speed gain Kv are associated with each other. Specifically, in this map 53a, the vehicle speed gain Kv is “0” when the vehicle speed V is equal to or lower than a predetermined vehicle speed V1 (V ≦ V1) and when the vehicle speed V is equal to or higher than a predetermined vehicle speed V2 (V ≧ V2). When the vehicle speed V is not less than the predetermined vehicle speed V1 ′ and not more than the predetermined vehicle speed V2 ′ (V1 ′ ≦ V ≦ V2 ′), the vehicle speed V is set to be “1”. When the vehicle speed V is in the range from the vehicle speed V1 to the vehicle speed V1 ′ (V1 <V <V1 ′), the vehicle speed gain Kv increases as the vehicle speed V increases (“0” → “1 In addition, when the vehicle speed V is in the range from the vehicle speed V2 ′ to the vehicle speed V2 (V2 ′ <V <V2), the vehicle speed gain Kv decreases as the vehicle speed V increases (“1” → “0”). ) Is set as follows. The vehicle speed gain calculation unit 53 calculates the vehicle speed gain Kv by referring to the input vehicle speed V in the map 53a.

  That is, the amplitude of the reverse input stress remaining as vibration in the steering system depends on the vibration characteristics of the suspension that supports the steered wheels 12, and is amplified in a predetermined vehicle speed region (V1 <V <V2) where resonance occurs in the suspension. Is done. The rattling noise generated in the speed reduction mechanism 24 also tends to be particularly noticeable in this predetermined vehicle speed region. That is, paradoxically speaking, when the vehicle speed V is not in the predetermined vehicle speed range (V ≦ V1 or V ≧ V2), the rattling noise in the speed reduction mechanism 24 is not particularly problematic.

  Considering this point, in the present embodiment, the vehicle speed gain calculation unit 53 calculates “0” as the vehicle speed gain Kv when the vehicle speed V is not in the predetermined vehicle speed region. That is, the assist force applied to the steering system is not reduced by correcting the rattle noise suppression compensation amount Ira * to “0”. And thereby, it has the structure which suppresses generation | occurrence | production of the rattling sound in the deceleration mechanism 24 effectively, without impairing steering feeling.

  The steering angle gain Kθ is a correction gain for correcting the rattle noise suppression compensation amount Ira * according to the steering angle θs. As shown in FIG. 7, the steering angle gain calculator 54 is provided with a map 54a in which the steering angle θs and the steering angle gain Kθ are associated with each other. Specifically, in this map 54a, the steering angle gain Kθ is “0” when the absolute value of the steering angle θs is greater than or equal to a predetermined threshold θ1 (| θs | ≧ θ1), and the absolute value of the steering angle θs. Is equal to or less than a predetermined threshold θ1 ′ (| θs | ≦ θ1 ′), it is set to be “1”. When the absolute value of the steering angle θs is in the range from the threshold value θ1 to the threshold value θ1 ′ (θ1 <θs <θ1 ′), the steering angle gain Kθ decreases as the absolute value of the steering angle θs increases. (“1” → “0”). Then, the steering angle gain calculator 54 calculates the steering angle gain Kθ by referring to the input steering angle θs in the map 54a.

  The steering speed gain Kω is a correction gain for correcting the rattle noise suppression compensation amount Ira * according to the steering speed ωs. As shown in FIG. 8, the steering speed gain calculator 55 is provided with a map 55a in which the steering speed ωs and the steering speed gain Kω are associated with each other. Specifically, in this map 55a, the steering speed gain Kω is “0” when the absolute value of the steering speed ωs is greater than or equal to a predetermined threshold ω1 (| ωs | ≧ ω1), and the absolute value of the steering speed ωs. Is less than or equal to a predetermined threshold value ω1 ′ (| ωs | ≦ ω1 ′), it is set to be “1”. When the absolute value of the steering speed ωs is in the range from the threshold value ω1 to the threshold value ω1 ′ (ω1 <ωs <ω1 ′), the steering speed gain Kω decreases as the absolute value of the steering speed ωs increases. (“1” → “0”). Then, the steering speed gain calculation unit 55 calculates the steering speed gain Kω by referring to the input steering speed ωs in the map 55a.

  The torque gain Kτ is a correction gain for correcting the rattle noise suppression compensation amount Ira * according to the steering torque τ. As shown in FIG. 9, the torque gain calculation unit 56 is provided with a map 56a in which the steering torque τ and the torque gain Kτ are associated with each other. Specifically, in this map 56a, the torque gain Kτ is “0” when the absolute value of the steering torque τ is greater than or equal to a predetermined threshold τ1 (| τ | ≧ τ1), and the absolute value of the steering torque τ is When it is equal to or smaller than the predetermined threshold value τ1 ′ (| τ | ≦ τ1 ′), it is set to be “1”. When the absolute value of the steering torque τ is in the range from the threshold value τ1 to the threshold value τ1 ′ (τ1 <τ <τ1 ′), the torque gain Kτ becomes smaller as the absolute value of the steering torque τ increases ( “1” → “0”). The torque gain calculator 56 calculates the torque gain Kτ by referring to the input steering torque τ in the map 56a.

  The yaw rate gain Kγ is a correction gain for correcting the rattle sound suppression compensation amount Ira * according to the yaw rate γ. As shown in FIG. 10, the yaw rate gain calculation unit 57 is provided with a map 57a in which the yaw rate γ and the yaw rate gain Kγ are associated with each other. Specifically, in this map 57a, the yaw rate gain Kγ is “0” when the absolute value of the yaw rate γ is equal to or larger than a predetermined threshold value γ1 (| γ | ≧ γ1), and the absolute value of the yaw rate γ is a predetermined value. When it is less than or equal to the threshold value γ1 ′ (| γ | ≦ γ1 ′), it is set to be “1”. When the absolute value of the yaw rate γ is in the range from the threshold value γ1 to the threshold value γ1 ′ (γ1 <γ <γ1 ′), the yaw rate gain Kγ decreases as the absolute value of the yaw rate γ increases (“1 "→" 0 "). The yaw rate gain calculation unit 57 calculates the yaw rate gain Kγ by referring to the input yaw rate γ in the map 57a.

  That is, when an aggressive steering operation by the driver is occurring, it is desirable to give priority to the assist of the steering operation over suppression of the rattling noise. In view of this point, in the present embodiment, the absolute value of the steering angle θs is equal to or greater than a predetermined threshold θ1 (| θs | ≧ θ1), the absolute value of the steering speed ωs is equal to or greater than a predetermined threshold ω1 (| ωs | ≧ ω1), Alternatively, if the absolute value of the steering torque τ is greater than or equal to the predetermined threshold τ1 (| τ | ≧ τ1) and the absolute value of the yaw rate γ is greater than or equal to the predetermined threshold γ1 (| γ | ≧ γ1), the driver actively It is presumed that the steering operation has occurred.

  That is, in the present embodiment, each of the threshold values θ1, ω1, τ1, and γ1 is set to a value that can be estimated as a result of an aggressive steering operation by the driver. When it is estimated that such an aggressive steering operation by the driver is occurring, each of the correction gain calculation units (54, 55, 56, 57) outputs the correction gain (Kθ) to be output. , Kω, Kτ, Kγ), “0” is calculated. That is, the assist force applied to the steering system is not reduced by correcting the rattle noise suppression compensation amount Ira * to “0”. And thereby, it has the structure which suppresses generation | occurrence | production of the rattling sound in the deceleration mechanism 24 effectively, without impairing steering feeling.

  In particular, even when the so-called “turnback steering” that reverses the steering operation direction occurs, the absolute value (| Δωp |) of the angular velocity difference value Δωp becomes a large value. However, by monitoring the steering torque τ, It is possible to distinguish between occurrence of turning-back steering and occurrence of application of reverse input to the steered wheels 12.

  As shown in FIG. 4, the rattle sound suppression compensation calculation unit 51 of the present embodiment is provided with a switching control unit 59. The basic compensation amount εra ′ after the multiplication of the correction gains (Kθ, Kω, Kτ, Kγ) by the multiplier 58 is input to the switching control unit 59 together with the brake signal Sbk.

  The switching control unit 59 of the present embodiment selects the basic compensation amount εra ′ as the output when the input brake signal Sbk is “off”, that is, during non-vehicle braking, and the brake signal Sbk is “on”. In some cases, that is, when the vehicle is braked, "0" is selected as the output. Then, the rattle sound suppression compensation calculation unit 51 outputs the basic compensation amount εra ′ or “0” output from the switching control unit 59 to the adder 49 as the rattle sound suppression compensation amount Ira *.

  That is, when braking the vehicle, priority should be given to applying assist force to the steering system in order to deal with vibrations transmitted to the steering system as a result of braking, rather than suppression of rattling noise. In the present embodiment, when the vehicle is braked, the rattle noise suppression compensation amount Ira * is set to “0”, and the assist force applied to the steering system is not reduced, thereby ensuring a good steering feeling during the vehicle braking. It has a configuration.

As described above, according to the present embodiment, the following operations and effects can be obtained.
(1) The motor 21 that is the drive source of the EPS actuator 22 is connected to the column shaft 8 via a reduction gear 24 that is engaged with a reduction gear 25 provided on the column shaft 8 and a motor gear 26 provided on the motor shaft 21a. Connected. The ECU 23 detects the rotational angular velocity (pinion angular velocity ωp) of the reduction gear 25 as the first angular velocity, and also calculates a second angular velocity (converted pinion angular velocity ωp_cnv) obtained by converting the rotational angular velocity of the motor gear 26 into the rotational angular velocity of the reduction gear 25. To detect. Then, when the difference value (angular velocity Δωp) between the first and second angular velocities is calculated and the difference value (absolute value of the angular velocity difference value Δωp) exceeds a predetermined threshold, the assist force applied to the steering system The operation of the EPS actuator 22 is controlled so as to reduce.

  That is, the rattling sound in the speed reduction mechanism 24 is generated when the reduction gear 25 (the teeth) as the first gear collides with the motor gear 26 (the teeth) as the second gear. When reverse input stress is applied, the reduction gear 25 and the motor gear 26 rotate at high speeds in opposite directions, that is, repeatedly collide with a large difference in rotational angular velocity between the two, thereby generating a large rattling noise.

  However, when a large angular velocity difference value Δωp (absolute value) corresponding to the application of reverse input stress is detected as in the above configuration, the motor gear 26 is reduced by reducing the assist force applied to the steering system. The rotational angular velocity when rotating in the direction opposite to the reduction gear 25 can be suppressed. Thereby, the rotation angular velocity difference at the time of both collision can be made small, As a result, generation | occurrence | production of the rattling sound in the deceleration mechanism 24 can be suppressed effectively.

  (2) The current command value calculation unit 45 calculates a rattle sound suppression amount Ira * for reducing the current command value Iq * (absolute value) corresponding to the target assist force based on the angular velocity difference value Δωp. A suppression compensation calculation unit 51 is provided, and the rattle sound suppression compensation calculation unit 51 includes a basic compensation amount calculation unit 52 that calculates a basic compensation amount εra that is a basic component of the rattle sound suppression compensation amount Ira *. The basic compensation amount calculation unit 52 increases the assist force as the absolute value (| Δωp |) of the angular velocity difference value Δωp increases in a region where the absolute value (| Δωp |) of the angular velocity difference value Δωp exceeds the threshold α1. A basic compensation amount εra to be reduced is calculated.

  According to the above configuration, as the absolute value (| Δωp |) of the angular velocity difference value Δωp at which the reduction gear 25 and the motor gear 26 collide strongly increases, the rotational angular velocity of the reduction gear 25 is suppressed and the impact is reduced. Can be relaxed. As a result, generation of rattling noise can be more effectively suppressed.

  (3) The rattle noise suppression compensation calculation unit 51 includes a vehicle speed gain calculation unit 53 that calculates a vehicle speed gain Kv for correcting the rattle noise suppression compensation amount Ira * according to the vehicle speed V. Then, the vehicle speed gain calculation unit 53 calculates “0” as the vehicle speed gain Kv when the vehicle speed V is not in the predetermined vehicle speed region (V ≦ V1 or V ≧ V2).

  According to the above-described configuration, the rattle noise suppression compensation amount Ira * is corrected to “0” at a vehicle speed at which the rattling noise in the speed reduction mechanism 24 does not particularly cause a problem, whereby the assist force applied to the steering system is not reduced. That is, the assist force is reduced only when the vehicle speed V is in a predetermined vehicle speed range (V1 <V <V2). As a result, it is possible to effectively suppress the occurrence of rattling noise in the speed reduction mechanism 24 without impairing the steering feeling.

  (4) The rattle noise suppression compensation calculation unit 51 includes a steering angle gain calculation unit 54 that calculates a steering angle gain Kθ for correcting the rattle noise suppression compensation amount Ira * according to the steering angle θs. Then, the steering angle gain calculation unit 54 outputs “0” as the steering angle gain Kθ when the absolute value of the steering angle θs is equal to or greater than a predetermined threshold θ1 (| θs | ≧ θ1).

  (5) The rattle noise suppression compensation calculation unit 51 includes a steering speed gain calculation unit 55 that calculates a steering speed gain Kω to correct the rattle noise suppression compensation amount Ira * according to the steering speed ωs. When the absolute value of the steering speed ωs is equal to or greater than the predetermined threshold ω1 (| ωs | ≧ ω1), the steering speed gain calculation unit 55 outputs “0” as the steering speed gain Kω.

  (6) The rattle noise suppression compensation calculation unit 51 includes a torque gain calculation unit 56 that calculates a torque gain Kτ for correcting the rattle noise suppression compensation amount Ira * according to the steering torque τ. When the absolute value of the steering torque τ is greater than or equal to a predetermined threshold τ1 (| τ | ≧ τ1), the torque gain calculation unit 56 outputs “0” as the yaw rate gain Kγ.

  (7) The rattle sound suppression compensation calculation unit 51 includes a yaw rate gain calculation unit 57 that calculates a yaw rate gain Kγ for correcting the rattle sound suppression compensation amount Ira * according to the yaw rate γ. The yaw rate gain calculation unit 57 outputs “0” as the yaw rate gain Kγ when the absolute value of the yaw rate γ is equal to or greater than the predetermined threshold value γ1 (| γ | ≧ γ1).

  That is, when an aggressive steering operation by the driver is occurring, it is desirable to give priority to the assist of the steering operation over suppression of the rattling noise. The presence of the steering angle θs greater than or equal to the predetermined threshold θ1, the steering speed ωs greater than or equal to the predetermined threshold ω1, the steering torque τ greater than the predetermined threshold τ1, or the yaw rate γ greater than or equal to the predetermined threshold γ1 is positive by the driver. This can be regarded as a result of steering operation.

  Therefore, according to the above configurations (4) to (7), when an active steering operation is performed by the driver, the rattle noise suppression compensation amount Ira * is corrected to “0” and Priority can be given to assisting steering operation. As a result, it is possible to effectively suppress the occurrence of rattling noise in the speed reduction mechanism 24 without impairing the steering feeling.

  (8) The rattle noise suppression compensation calculation unit 51 includes a switching control unit 59, and the basic compensation amount εra ′ after each correction gain (Kθ, Kω, Kτ, Kγ) is multiplied by the switching control unit 59. At the same time, a brake signal Sbk is input. Then, when the brake signal Sbk is “ON”, that is, when the vehicle is braked, the switching control unit 59 selects “0” as the output, and the rattle sound suppression compensation calculating unit 51 outputs from the switching control unit 59. The output “0” is output as the rattle noise suppression compensation amount Ira *.

  According to the above configuration, when the vehicle is braked, the rattle noise suppression compensation amount Ira * is set to “0” to give priority to giving the assist force to the steering system, so that the vibration transmitted to the steering system accompanying the braking is also dealt with. can do. As a result, it is possible to effectively suppress the occurrence of rattling noise in the speed reduction mechanism 24 without impairing the steering feeling.

  (9) The current command value calculation unit 45 calculates a torque inertia compensation amount Iti * based on a differential value of the steering torque τ (steering torque differential value dτ) as a compensation component of the basic assist control amount Ias *. Part 48. Then, the current command value calculation unit 45 calculates the current command value Iq * as the target assist force by superimposing the torque inertia compensation amount Iti * on the basic assist control amount Ias *.

  That is, by executing compensation control based on such a steering torque differential value dτ, the phase of the motor gear 26 (motor 21) is shifted (advanced by 90 °). For this reason, when performing compensation control based on such steering torque differential value dτ, the absolute value (| Δωp |) of the angular velocity difference value Δωp tends to be large, and the rattling noise caused by this tends to be prominent. There is. Therefore, a more remarkable effect can be obtained by applying the configurations (1) to (8) above to those that perform such compensation control.

(Second Embodiment)
Hereinafter, a second embodiment in which the present invention is embodied in a column-type electric power steering device (EPS) will be described with reference to the drawings. The main difference between this embodiment and the first embodiment is only the mode of the rattle noise suppression compensation control. For this reason, for convenience of explanation, the same parts as those in the first embodiment are denoted by the same reference numerals, and the explanation thereof is omitted.

  As shown in FIG. 11, in the present embodiment, the current command value calculation unit 60 corresponds to the rattle sound suppression compensation calculation unit 51 in the current command value calculation unit 45 of the first embodiment. A suppression gain calculation unit 61 is provided. The rattle noise suppression gain calculation unit 61 then outputs a current command value Iq * (absolute value) output from the current command value calculation unit 60 in a region where the absolute value of the input angular velocity difference value Δωp exceeds a predetermined threshold β1. The rattle noise suppression supplement gain Kra is calculated so as to reduce the assist force generated by the EPS actuator 22.

  The rattle noise suppression supplement gain Kra calculated by the rattle noise suppression gain calculation unit 61 is input to the multiplier 63 together with the basic assist control amount Ias ** after the torque inertia compensation amount Iti * is superimposed in the adder 62. The In the multiplier 63, the current command value calculation unit 60 of the present embodiment outputs a motor control signal as a current command value Iq *, which is a value obtained by multiplying the basic assist control amount Ias ** by the rattle noise suppression supplement gain Kra. Thus, the assist force generated by the EPS actuator 22 is reduced.

Next, the configuration of the rattle sound suppression gain calculation unit will be described.
As shown in FIG. 12, the rattle sound suppression gain calculation unit 61 includes a basic gain calculation unit 64 that corresponds to the basic compensation amount calculation unit 52 of the rattle sound suppression compensation calculation unit 51 in the first embodiment. The basic gain calculator 64 calculates a basic gain Kbs, which is a basic component of the rattle noise suppression supplement gain Kra, based on the input angular velocity difference value Δωp.

  The basic gain Kbs calculated by the basic gain calculation unit 64 is input to the multiplier 65. The multiplier 65 includes the basic gain Kbs, the vehicle speed gain Kv output from the vehicle speed gain calculator 53, the steering angle gain Kθ output from the steering angle gain calculator 54, and the steering speed output from the steering speed gain calculator 55. The gain Kω, the torque gain Kτ output from the torque gain calculation unit 56, and the yaw rate gain Kγ output from the yaw rate gain calculation unit 57 are input. The rattle noise suppression gain calculator 61 includes an acceleration gain calculator 66 that calculates an acceleration gain Kg based on the longitudinal acceleration G of the vehicle detected by an acceleration sensor (not shown). The acceleration gain Kg calculated by 66 is also input to the multiplier 65. The correction gains (Kv, Kθ, Kω, Kτ, Kγ, Kg) output from the correction gain calculators (53, 54, 55, 56, 57, 66) are converted into basic gains Kbs in the multiplier 65. To get on.

  Here, in the present embodiment, the basic gain Kbs ′ after multiplication of each correction gain (Kv, Kθ, Kω, Kτ, Kγ, Kg) in the multiplier 65 is input to the subtractor 67. Then, the rattle noise suppression gain calculation unit 61 uses the value (1−Kbs ′) obtained by subtracting the basic gain Kbs ′ from “1” calculated by the subtractor 67 as the rattle noise suppression complementary gain Kra, and the above multiplier. To 63. Accordingly, the basic gain Kbs calculated by the basic gain calculation unit 64 is larger and the current command value Iq * (absolute value) output from the current command value calculation unit 60 is reduced as the value is closer to “1”. That is, the assist force generated by the EPS actuator 22 is reduced.

  As shown in FIG. 13, the basic gain calculator 64 has a map 64a in which the angular velocity difference value Δωp and the basic gain Kbs are associated with each other. The basic gain calculator 64 calculates the basic gain Kbs by referring to the input angular velocity difference value Δωp in the map 64a.

  More specifically, in the map 64a, the basic gain Kbs is “0” when the absolute value (| Δωp |) of the angular velocity difference value Δωp is equal to or smaller than a predetermined threshold value β1 (| Δωp | ≦ β1). When the absolute value (| Δωp |) of Δωp is equal to or greater than a predetermined threshold value β1 ′ (| Δωp | ≧ β1 ′), it is set to be “1”. When the absolute value (| Δωp |) of the angular velocity difference value Δωp is in the range from the threshold value β1 to the threshold value β1 ′ (β1 <| Δωp | <β1 ′), the absolute value (| Δωp | ) Is set to increase as the value increases.

  That is, the basic gain calculation unit 64 of the present embodiment has a larger current output from the current command value calculation unit 60 when the absolute value (| Δωp |) of the angular velocity difference value Δωp exceeds the predetermined threshold value β1. The basic gain Kbs is calculated so as to reduce the command value Iq * (absolute value thereof). As a result, when a large angular velocity difference value Δωp (absolute value) corresponding to application of reverse input stress is detected, the assist force applied to the steering system is reduced, that is, the motor gear 26 is opposite to the reduction gear 25. The rotational angular velocity when rotating in the direction is suppressed, and the rattling noise generated in the speed reduction mechanism 24 is suppressed.

  Further, as shown in FIG. 14, the acceleration gain calculation unit 66 has a map 66a in which the longitudinal acceleration G and the acceleration gain Kg are associated with each other. In this map 66a, the acceleration gain Kg is “0” when the longitudinal acceleration G is a value “−” from the predetermined threshold G1, and the acceleration gain Kg is a value “+” from the predetermined threshold G1 ′. Is set to be “1”. Here, a value of “−” that can be estimated that the vehicle is in a braking state is set as the threshold G1. When the longitudinal acceleration G is in the range from the threshold value G1 to the threshold value G1 ′ (G1 <G <G1 ′), the acceleration gain Kg decreases as the longitudinal acceleration G takes a larger “−” value. (“1” → “0”). The acceleration gain calculation unit 66 calculates the acceleration gain Kg by referring to the map 66a for the input longitudinal acceleration G.

  That is, in the present embodiment, the acceleration gain calculation unit 66 calculates “0” as the acceleration gain Kg when the input longitudinal acceleration G is in a region where it can be estimated that the vehicle is in a braking state. It is configured. As a result, when the vehicle is braked, the basic gain Kbs ′ after multiplication by the acceleration gain Kg is set to “0”, that is, priority is given to assisting the steering system. The configuration can cope with transmitted vibration.

As described above, even when the current command value calculation unit 60 and the rattle sound suppression gain calculation unit 61 are configured as in the present embodiment, the same effects as those of the first embodiment can be obtained.
In addition, you may change each said embodiment as follows.

  In each of the above-described embodiments, the present invention is embodied as a so-called column-type EPS 1. However, in the present invention, the motor and the steering shaft are driven and connected via a speed reduction mechanism that meshes the first and second gears. For example, the present invention may be applied to a so-called pinion type EPS that applies assist force to the pinion shaft.

  In each of the above embodiments, the present invention is embodied in EPS 1 that performs compensation control (torque inertia compensation control) based on the differential value of steering torque τ (steering torque differential value dτ). You may apply to what does not perform the compensation control based on the derivative value of steering torque (tau).

  In each of the above embodiments, the reduction gear 25 is the first gear and the motor gear 26 is the second gear. However, this may be reversed. That is, in each of the above embodiments, the second angular velocity is obtained by converting the rotational angular velocity of the motor gear 26 into the rotational angular velocity of the reduction gear 25 with the pinion angular velocity ωp that is the rotational angular velocity of the reduction gear 25 as a reference (first angular velocity). (Conversion pinion angular velocity ωp_cnv) was detected. However, the present invention is not limited to this, and the second angular velocity (converted motor angular velocity) is obtained by converting the rotational angular velocity of the reduction gear 25 into the rotational angular velocity of the motor gear 26 with the motor angular velocity which is the rotational angular velocity of the motor gear 26 as the first angular velocity. It is good also as a structure to detect.

  The correction calculations (correction gain calculations) executed in the rattle sound suppression compensation calculation unit 51 in the first embodiment and the rattle sound suppression gain calculation unit 61 in the second embodiment are not necessarily all of these. Is not necessary, and may be selected or arbitrarily changed as appropriate.

  For example, for those having substantially the same functions as the vehicle speed gain calculation unit 53, the steering angle gain calculation unit 54, the steering speed gain calculation unit 55, and the yaw rate gain calculation unit 57, it is necessary to execute all these correction calculations. However, they may be appropriately selected and arbitrarily combined.

  Further, the switching control unit 59 provided in the rattle sound suppression compensation calculation unit 51 in the first embodiment and the acceleration gain calculation unit 66 provided in the rattle sound suppression gain calculation unit 61 in the second embodiment are also described. Any of these may be selected. For example, in the configuration in which the assist force is reduced by superimposing the rattle noise suppression compensation amount Ira * as in the first embodiment, the acceleration gain calculation unit 66 is provided to give priority to assist force application during vehicle braking. It is good also as a structure which aims at.

Further, it may be configured such that the presence or absence of an aggressive steering operation is directly determined, and the assist force is not reduced when the active steering operation is performed.
In each embodiment described above, it is determined whether or not the assist force reduction control is executed in the map calculation in the rattle sound suppression compensation calculation unit 51 and the rattle sound suppression gain calculation unit 61. However, the present invention is not limited to this, and a configuration in which determination based on the angular velocity difference value Δωp is more directly performed may be employed.

  That is, as shown in the flowchart of FIG. 15, it is determined whether or not the absolute value of the angular velocity difference value Δωp exceeds a predetermined threshold value ω0 (step 101). If the predetermined threshold value ω0 is exceeded (| Δωp |> ω0, step 101: YES), assist force reduction control is executed (step 102). If the threshold value ω0 is not exceeded (| Δωp | ≦ ω0, step 101: NO), the assist force may not be reduced (normal control, step 103).

The schematic block diagram of an electric power steering device (EPS). The control block diagram of EPS in 1st Embodiment. The control block diagram of a torque inertia compensation control part. The schematic block diagram of a rattle sound suppression compensation calculating part. The schematic block diagram of a basic compensation amount calculating part. The schematic block diagram of a vehicle speed gain calculating part. The schematic block diagram of a steering angle gain calculating part. The schematic block diagram of a steering speed gain calculating part. The schematic block diagram of a torque gain calculating part. The schematic block diagram of a yaw rate gain calculating part. The control block diagram of EPS in 2nd Embodiment. The control block diagram of a rattle sound suppression gain calculating part. The schematic block diagram of a basic gain calculating part. The schematic block diagram of an acceleration gain calculating part. The flowchart which shows the process sequence of the rattle noise suppression compensation control of another example. The schematic diagram which shows the structure of a torque sensor roughly. Explanatory drawing which shows the generation | occurrence | production mechanism of the rattling sound (rattle sound) in a deceleration mechanism.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering device (EPS), 2 ... Steering, 3 ... Steering shaft, 8 ... Column shaft, 8a ... First shaft, 8b ... Second shaft, 9 ... Intermediate shaft, 10 ... Pinion shaft, 12 ... Roll Steering wheel, 21 ... motor, 21a ... motor shaft, 22 ... EPS actuator, 23 ... ECU, 24 ... deceleration mechanism, 25 ... reduction gear, 26 ... motor gear, 31 ... torque sensor, 33 ... torsion bar, 34a ... first angle Sensor 34b ... Second angle sensor 35 ... Vehicle speed sensor 36 ... Yaw rate sensor 41 ... Microcomputer 42 ... Drive circuit 44 ... Rotation angle sensor 45, 60 ... Current command value calculation unit 46 ... Motor control signal Output unit 47 ... Basic assist control unit 48 ... Torque inertia compensation control unit 51 ... Rattle noise suppression Compensation calculation unit, 52 ... basic compensation amount calculation unit, 53 ... vehicle speed gain calculation unit, 54 ... steering angle gain calculation unit, 55 ... steering speed gain calculation unit, 56 ... torque gain calculation unit, 57 ... yaw rate gain calculation unit, 59 ... switching control unit, 61 ... rattle sound suppression gain calculation unit, 64 ... basic gain calculation unit, 66 ... acceleration gain calculation unit, Iq * ... current command value, Ias *, Ias ** ... basic assist control amount, Iti * ... Torque inertia compensation amount, Ira * ... Rattle sound suppression compensation amount, εra, εra '... Basic compensation amount, Kra * ... Rattle sound suppression gain, Kbs, Kbs' ... Basic gain, θp ... Pinion angle, ωp ... Pinion angular velocity, θm ... Motor rotation angle, θp_cnv ... converted pinion angle, ωp_cnv ... converted pinion angular velocity, Δωp ... angular velocity difference value, α1, β1, β1 ', ω0 ... threshold, θs ... steering angle, θ1, θ1' ... threshold, Kθ ... steering angle Gain, ωs ... steering speed, ω1, ω '... threshold, Kω ... steering speed gain, V, V1, V1', V2, V2 '... vehicle speed, Kv ... vehicle speed gain, τ ... steering torque, τ1, τ1' ... threshold, dτ ... steering torque differential value, Kτ ... Torque gain, γ ... yaw rate, γ1, γ1 '... threshold, Kγ ... yaw rate gain, G ... longitudinal acceleration, Kg ... acceleration gain, G1, G1' ... threshold, Sbk ... brake signal.

Claims (11)

A steering force assisting device that applies an assist force for assisting a steering operation to the steering system by rotationally driving a steering shaft using a motor as a drive source, and the operation of the steering force assisting device through the supply of driving power to the motor And an electric power steering device that is drivingly connected to the steering shaft via a speed reduction mechanism that meshes the first and second gears,
First angular velocity detection means for detecting a rotational angular velocity of the first gear as a first angular velocity;
And a second angular velocity detecting means for detecting a rotational angular velocity of the second gear as the second angular velocity in terms of angular velocity of said first gear,
The control means calculates a difference value between the detected first and second angular velocities, and when the absolute value of the difference value exceeds a predetermined threshold, performs the control to reduce the assist force. An electric power steering device characterized by that. The electric power steering apparatus according to claim 1, wherein
The electric power steering apparatus characterized in that the control means performs the control so as to greatly reduce the assist force as the absolute value of the difference value is larger. In the electric power steering device according to claim 1 or 2,
The electric power steering apparatus characterized in that the control means reduces the assist force only when the vehicle speed is in a predetermined vehicle speed range. In the electric power steering device according to any one of claims 1 to 3,
The control means does not reduce the assist force when the absolute value of the steering angle is greater than or equal to a predetermined threshold value. In the electric power steering device according to any one of claims 1 to 4,
The control means does not reduce the assist force when the absolute value of the steering speed is greater than or equal to a predetermined threshold value. In the electric power steering apparatus according to any one of claims 1 to 5,
The control means does not reduce the assist force when the absolute value of the steering torque is equal to or greater than a predetermined threshold value. In the electric power steering device according to any one of claims 1 to 6,
The control means does not reduce the assist force when the absolute value of the yaw rate of the vehicle is greater than or equal to a predetermined threshold value. In the electric power steering device according to any one of claims 1 to 7 ,
The control means does not reduce the assist force during vehicle braking;
An electric power steering device. In the electric power steering device according to any one of claims 1 to 8 ,
The control means reduces the assist force by superimposing a compensation amount based on a difference value between the first and second angular velocities on a basic assist component;
An electric power steering device. In the electric power steering device according to any one of claims 1 to 8 ,
The control means reduces the assist force by multiplying a basic assist component by a compensation gain calculated based on a difference value between the first and second angular velocities.
An electric power steering device. In the electric power steering device according to any one of claims 1 to 10,
The control means calculates a target assist force to be generated by the steering force assisting device by superimposing a compensation amount based on a differential value of the steering torque on the basic assist component;
An electric power steering device.

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