JP2011025829A - Power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power steering device which suppresses a shimmy change without divergence, underflow, or overflow of an output value. <P>SOLUTION: The power steering device includes a vibration-suppression signal calculating unit 22 that calculates a vibration-suppression signal T<SB>v</SB>for suppressing shimmy change in an electronic control unit, and has characteristics in which a difference between a phase occurred when a shimmy change component Sm is generated and a phase occurred when a steering force based on the vibration suppression signal T<SB>v</SB>is generated in a power cylinder is larger than 90 degrees and smaller than 270 degrees. The vibration-suppression signal calculating unit 22 is constituted of a band-pass filter 31 for extracting the shimmy change component Sm from a steering torque signal T detected by a torque sensor, and of a phase correcting means 32 for correcting the phase difference by reversing a phase of the extracted shimmy change component Sm. Thus, the shimmy change component Sm can be decreased easily and favorably. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an improvement of a power steering device that is applied to, for example, an automobile and assists a driver's steering force by a driving force or hydraulic pressure of an electric motor.

  When an automobile is running, the tire and wheel unbalance, rattling between the hub and wheel, etc. are used as a vibration source, which is amplified by resonating with the suspension, and this amplified vibration is, for example, rack and pinion A so-called shimmy that causes vibration in the direction of rotation of the steering wheel is transmitted to the steering wheel via a steering mechanism such as a mechanism, which causes discomfort to the occupant.

  In view of this, various techniques have been proposed in order to suppress adverse effects due to the occurrence of such fluctuating torque (hereinafter referred to as “Shimi fluctuation”), and one example thereof is described in Patent Document 1 below. There is something that was done.

  That is, in this power steering apparatus, a SAT estimation unit that estimates so-called self-aligning torque (SAT) or a SAT measurement unit that measures SAT by a sensor is provided, and a SAT estimation value or SAT estimated by the SAT estimation unit. After the SAT value measured by the measurement unit is adjusted by the gain unit, this is added to the steering assist command value and output as a current command value, and the disturbance is reduced by using such a compensation signal. Therefore, suppression of the shimmy variation is attempted.

  Here, the shimmy has a large frequency range in which vibration is large due to the relationship with vehicle speed and suspension characteristics. Therefore, the conventional power steering device uses a bandpass filter to increase the vibration from the SAT value. Although the frequency range (frequency component) is extracted, depending on the characteristics of the steering system, there is a difference (phase difference) between the phase of the frequency component of the disturbance vibration and the phase of the compensation signal due to transmission delay by the system. As a result, disturbance vibrations cannot be suppressed appropriately. Therefore, in the conventional power steering device, a phase adjustment unit that corrects the phase of the frequency component is provided, and the phase of the frequency component is corrected by the phase adjustment unit, thereby adversely affecting the characteristics of the steering system. The above-mentioned shimmy fluctuation can be effectively suppressed.

  That is, in the conventional power steering device, when correcting the phase of the frequency component, the phase adjusting unit corrects (advances) the phase of the frequency component in consideration of a delay due to the steering system. Using a so-called high-pass filter, which is a filter, and adding the gain obtained by multiplying the frequency component whose phase has been advanced by a predetermined amount through the high-pass filter to the steering assist command value and outputting it as a current command value This cancels out the frequency component, thereby effectively suppressing the Shimmy variation.

JP 2008-18825 A

  However, in the conventional power steering apparatus, when the delay due to the steering system is large in the frequency band (10 Hz to 15 Hz) of the Shimmy fluctuation, the phase adjustment unit always compensates for this delay. It is necessary to introduce a high-order filter. For this reason, there is a problem that the output value diverges, underflows or overflows depending on the set cutoff frequency.

  The present invention has been devised in view of such a technical problem, and provides a power steering device capable of suppressing Shimmy fluctuations without causing an output value to diverge, underflow or overflow.

  According to the first aspect of the present invention, there is provided a power cylinder having a pair of pressure chambers that assists a steering force of a steering mechanism linked to a steered wheel of a vehicle and is internally separated, and a pair of the power cylinders. A reversible pump having a pair of discharge ports for selectively supplying hydraulic fluid to the pressure chambers, one side of the pair of pressure chambers of the power cylinder and one side of the pair of discharge ports of the reversible pump A second oil passage connecting the other side of the pair of pressure chambers of the power cylinder and the other side of the pair of discharge ports of the reversible pump, and the reversible pump An electric motor for driving the electric motor, a torque sensor for detecting a steering torque acting on the steering mechanism, an electric motor control circuit for outputting an electric motor control signal for controlling the electric motor, and an electric motor control circuit. First motor control signal based on An assist signal calculation unit for calculating; a first filter for extracting a predetermined frequency component of the steering torque detected by the torque sensor; and a second filter for reducing the predetermined frequency component provided in the motor control circuit. A vibration suppression signal calculation unit for calculating an electric motor control signal, and a phase when the predetermined frequency component is generated and a phase when a steering force based on the second electric motor control signal is generated in the power cylinder A power steering device having a difference larger than 90 degrees and smaller than 270 degrees, wherein a second filter that outputs a phase inversion signal for inverting the phase of the predetermined frequency component is provided, and the vibration suppression In the signal calculation unit, the second motor control signal is calculated based on the phase inversion signal of the predetermined frequency component. Is characterized in that form was.

  According to the present invention, since the second motor control signal is calculated based on the phase inversion signal of the predetermined frequency component, a higher order is obtained in the range where the phase difference is larger than 90 degrees and smaller than 270 degrees. The phase of the predetermined frequency component can be corrected without using the filter. Thereby, when performing the said correction | amendment, the said predetermined frequency component can be reduced, without the output value of an electric motor control signal spreading | deviating or underflowing or overflowing.

1 is a system configuration diagram of a power steering apparatus according to the present invention. FIG. 2 is a configuration block diagram of the electronic control unit shown in FIG. 1. It is a control block diagram of the vibration suppression signal calculating part shown in FIG. It is a graph showing the waveform before and behind phase correction of the predetermined frequency component by the phase correction means shown in FIG. It is a flowchart which shows the control content about shimmy suppression of the power steering apparatus which concerns on 1st Embodiment of this invention. It is a control block diagram which shows an example of the control block structure of the vibration suppression signal calculating part which concerns on 2nd Embodiment of this invention. It is a control block diagram which shows the other example of the control block structure of the vibration suppression signal calculating part which concerns on the same embodiment. It is a flowchart which shows the control content about shimmy suppression of the power steering apparatus which concerns on the same embodiment. It is a block diagram of the configuration of an electronic control unit according to a third embodiment of the present invention. FIG. 10 is a control block diagram of a vibration suppression signal calculation unit shown in FIG. 9. It is a graph showing the relationship between the vehicle speed and gain in the vehicle speed gain table shown in FIG. It is a flowchart which shows the control content about shimmy suppression of the power steering apparatus which concerns on the same embodiment.

  Hereinafter, embodiments of a power steering apparatus according to the present invention will be described in detail with reference to the drawings. In each of the embodiments, the power steering apparatus is applied to a rack and pinion hydraulic power steering apparatus for an automobile.

  FIGS. 1 to 5 show a first embodiment of the present invention. As shown in FIG. 1, this power steering device transmits a steering force (steering torque) of a driver to a steered wheel (not shown). Means 1, steering force assist means 2 for generating a steering assist force (steering assist torque) by hydraulic pressure based on the steering torque of the driver input to the steering force transmission means 1, and steering in the steering force assist means 2 It mainly comprises a hydraulic pressure supply means 3 for supplying hydraulic pressure for generating assist torque, and an electric control circuit 4 for controlling the steering force assist means 2 and the hydraulic pressure supply means 3.

  The steering force transmitting means 1 is linked to a steering wheel 11 at one end in the axial direction so as to be integrally rotatable, and an input shaft 12 for performing steering input from the driver, and a torsion bar not shown in the drawing with respect to the input shaft 12 at one end in the axial direction. Via an output shaft 13 having a pinion tooth outside the figure on the outer periphery on the other end side, and a rack tooth outside the figure meshing with the pinion tooth. A rack shaft 14 that is provided so as to be movable in the axial direction by rotation and whose both axial ends are linked to the steered wheels is mainly configured. Then, as is well known, by rotating the steering wheel 11, the input shaft 12 is rotated and the torsion bar is twisted. By the elastic force of the torsion bar generated based on the torsional deformation of the torsion bar, The output shaft 13 rotates following the input shaft 12. As a result, the rotational motion of the output shaft 13 is converted into the linear motion of the rack shaft 14 by a rack and pinion mechanism comprising the output shaft 13 and the rack shaft 14, and the rack shaft 14 moves in the left-right direction. The steered wheels are steered.

  The steering force assisting means 2 is constituted by a power cylinder 15 that assists the steering force by generating a propulsive force on the rack shaft 14 with a hydraulic pressure acting on a pair of pressure chambers P1, P2 separated inside. . The power cylinder 15 includes a cylinder tube 15a formed in a substantially cylindrical shape, the rack shaft 14 serving as a piston rod extending in the axial direction, and a cylinder tube formed by a piston 15b fixed to the outer periphery of the rack shaft 14. A first pressure chamber P1 and a second pressure chamber P2, which are a pair of pressure chambers, are separated in 15a. The hydraulic pressure supplied to the pressure chambers P1 and P2 generates a propulsive force for the rack shaft 14, thereby assisting the steering output.

  The hydraulic pressure supply means 3 includes a first discharge port 16 a and a second discharge port 16 b that are a pair of discharge ports corresponding to the first and second pressure chambers P 1 and P 2 of the power cylinder 15, and the rotation direction of the steering wheel 11. The pump 16 is a reversible bidirectional pump that selectively supplies hydraulic pressure to each of the pressure chambers P1 and P2 in response to the pressure, and an electric motor 17 that is an electric motor that drives the pump 16. The first discharge port 16a and the first pressure chamber P1 are connected via the first hydraulic pipe 10a that is the first oil passage, while the second discharge port 16b and the second pressure chamber P2 are the second oil passage. It is connected via a certain second hydraulic pipe 10b. Both the hydraulic pipes 10a and 10b are formed of a rubber material (rubber tube). The electric motor 17 is supplied from a vehicle-mounted battery 30 based on detection results of a torque sensor 18 disposed on the input shaft 12 and a vehicle speed sensor 19 disposed on a brake control device provided on each wheel (not shown). It is driven and controlled by the electronic control unit 20 constituting the electric control circuit 4 with electric power. That is, when the driver steers, the rotation direction of the electric motor 17 is switched according to the steering direction, and the pump 16 is turned on to generate the steering assist torque according to the driver's steering torque in the power cylinder 15. It is designed to rotate.

As shown in FIG. 2, the electronic control unit 20 includes a steering assist signal (first motor control signal according to the present invention) T _a related to the steering assist torque _Tan based on the steering torque signal T from the torque sensor 18. An assist signal calculation unit 21 for calculating the steering torque signal T and the vehicle speed signal V from the vehicle speed sensor 19 are input to the assist signal calculation unit 21, respectively. based on _n and the vehicle speed V _n and calculates the steering assist torque T _an,. Furthermore, this electronic control unit 20, the vibration suppressing signal calculating section 22 for calculating a (second motor control signal according to the present invention) T _v vibration suppression signal according to suppress shimmy variation suppression torque T _vn shimmy variation The shimming fluctuation suppression torque T _vn is calculated based on the steering torque T _n when the steering torque signal T from the torque sensor 18 is input to the vibration suppression signal calculation unit 22. . Thus, the electronic control unit 20, the minus the shimmy variation suppression torque T _vn calculated by the vibration suppression signal calculation unit 22 from the calculated steering assist torque T _an by the assist-signal calculation section 21, final An assist torque signal AT that is a current command value for the electric motor 17 is output.

Assist torque signal AT which is calculated as described above is output to a limiter 23 for limiting the command torque AT _r for the electric motor 17 based on the torque limit signal T _r from the overheat protection operation unit 24, the limiter 23 in, in a limited range based on the torque limit signal T _r from the overheat protection operation unit 24, so as to output to the motor control unit 25 of the assist torque signal aT as the command torque aT _r to the electric motor 17 Yes. The heating protection calculation unit 24 includes a temperature sensor signal Th related to information on the temperature Th _n of the motor drive unit 26 detected by a temperature sensor 28 disposed in the vicinity of the motor drive unit 26 described later, and a current described later. and information of the current I supplied to the electric motor 17 from the sensor 27, based on the torque limit value is a command value for limiting the assist torque T _a so as to be within the normal movable temperature range of the electronic controller 20 and electric motor 17 By calculating T _rn and outputting the calculation result as the torque limit signal _Tr to the motor control unit 24, the limiter 23 limits the command torque AT _r output to the motor control unit 24. .

In the motor control unit 25, the electric motor from the motor rotation position calculation unit 29 that is provided on the electric motor 17 and is calculated based on the detection result of the rotation angle sensor 17 a that detects the rotation angle R _θ of the electric motor 17. 17 rotational position _Rp information and U-phase, V-phase, and W-phase currents I _U , I _V , I _W from a current sensor 27 provided between the motor drive unit 26 and the electric motor 17 described later. Information is input, and a current composed of three layers of U phase, V phase, and W phase is converted into a two-phase current, and a drive signal (PWM signal) of the electric motor 17 by feedback control by so-called PI control or the like. D is generated, and this PWM signal D is output to the motor drive unit 26. The motor drive unit 16 is composed of a power element (not shown) such as a so-called FET, and switches the power element in accordance with the PWM signal D, thereby energizing the electric motor 17 with a control current. ing. The electric motor 17 is driven and controlled based on this control current, so that an optimum assist torque AT that can suppress shimmy fluctuations is generated in the power cylinder 15 via the pump 16.

Subsequently, the configuration of the vibration suppression signal calculation unit 22 will be described in more detail. As shown in FIG. 3, the vibration suppression signal calculation unit 22 has a shimmy variation from the steering torque signal T output from the torque sensor 18. The bandpass filter 31 which is the first filter according to the present invention for extracting the shimmy fluctuation component Sm which is a predetermined frequency component (10 Hz to 15 Hz) according to the above, and the shimmy fluctuation component Sm extracted by the bandpass filter 31 Shimmy fluctuation suppression by multiplying the shimmy fluctuation component Sm ′ corrected by the phase correction means 32, which is the second filter according to the present invention for correcting the phase, by the torque conversion coefficient K. And a gain multiplier 33 for obtaining torque T _vn . Here, in the power steering apparatus, as described above, depending on the characteristics of the steering system, the vibration suppression signal related to the phase of the shimmy variation component Sm and the shimmy variation suppression torque _Tvn due to the transmission delay of the steering system. T _v may differences (phase difference) occurs between the phases of, in this case the phase difference is large, specifically, when the phase difference is smaller than 270 degrees greater than 90 degrees, the The phase correction means 32 inverts the sign of the shimmy fluctuation component Sm shown by the broken line in FIG. 4 extracted by the bandpass filter 31, that is, by applying “−1” to the shimmy fluctuation component. The phase of the extracted shimmy fluctuation component Sm is corrected. That is, when the phase difference is within the predetermined range, the phase inversion signal as described above is output from the phase correction means 32, and the shimmy fluctuation component Sm extracted based on the phase inversion signal is output. By performing the phase correction, as shown by a solid line in FIG. 4, the phase of the extracted shimmy fluctuation component Sm is advanced by 180 degrees.

  In this embodiment, when the phase difference is within the predetermined range, the phase correction by the sign inversion is performed. When the phase difference is outside the predetermined range, the sign inversion is If the phase difference is greater than 0 degree and 90 degrees or less as in the prior art, the phase of the shimmy fluctuation component Sm is delayed using a low-pass filter. If the angle is 270 degrees or more and smaller than 360 degrees, the phase of the shimmy fluctuation component Sm can be corrected by using the high-pass filter to advance the phase of the shimmy fluctuation component Sm. In other words, if the phase difference is outside the predetermined range, even if the phase correction of the shimmy fluctuation component Sm is simply performed using a low-pass filter or a high-pass filter as in the conventional technique, Since it is not necessary to use a high-order filter, the technical problem of the present invention is not caused.

Hereinafter, the control content of the shimmy variation suppression control of the power steering apparatus according to the present embodiment will be described along the flowchart shown in FIG. 5. First, the electronic control unit 20 first outputs the steering torque output from the torque sensor 18. After reading the signal T (step S11), the torque acting on the torsion bar is calculated based on the read steering torque signal T (step S12). After that, the shimmy fluctuation component Sm is extracted by passing the calculated torsion bar torque through the bandpass filter 31 (step S13), and the phase of the shimmy fluctuation component Sm is inverted by inverting the sign of the extracted shimmy fluctuation component Sm. Is advanced by 180 degrees (step S14). Then, the shimmy fluctuation suppression torque T _vn is calculated by multiplying the shimmy fluctuation component Sm ′ subjected to the phase correction by the sign inversion by the torque conversion coefficient K (step S15), and the calculated shimmy fluctuation suppression torque T _vn. assist torque signal T _a is a current command value to the electric motor 17 is obtained by subtracting from the steering assist torque T _an calculated in the assist signal calculating section 21 (step S16), and the program is terminated Will be.

As described above, the vibration suppression signal calculation unit 22 calculates the shimmy variation suppression torque _Tvn for the shimmy variation component Sm extracted by the bandpass filter 31 based on the phase inversion signal by the phase correction unit 32, that is, the extraction. Since the sign of the shimmy variation component Sm is inverted and the phase of the shimmy variation component Sm is corrected, the vibration suppression signal T related to the phase of the extracted shimmy variation component Sm and the shimmy variation suppression torque _{Tvn. When} the phase difference from the phase of _v is larger than 90 degrees and smaller than 270 degrees, the phase of the extracted shimmy fluctuation component Sm can be corrected very easily without using a high-order filter. It becomes. Accordingly, when performing the correction, the output value of the assist torque signal T _a is divergent, or reduce shimmy fluctuation component Sm without underflow or overflows, it is possible to suppress the shimmy variations.

  Further, in the present embodiment, since the first and second hydraulic pipes 10a and 10b are both made of rubber tubes, the merit of improving the layout of the hydraulic pipes and improving the vibration absorption. There is. On the other hand, the hydraulic pipes 10a and 10b constituted by rubber tubes in this way are elastic in the radial direction due to the elasticity of the rubber material, and when hydraulic pressure acts on these hydraulic pipes 10a and 10b, However, there is a demerit that the hydraulic pipes 10a and 10b are expanded by the hydraulic pressure, and the phase of the assist torque is likely to be delayed by the expansion of the pipes. The effects of the present invention according to the above will work more effectively.

  FIGS. 6-8 has shown 2nd Embodiment of the power steering apparatus which concerns on this invention, and changes the structure of the vibration suppression signal calculating part 22 based on the said 1st Embodiment. Accordingly, since the basic configuration is the same as that of the first embodiment, the same configuration as that of the first embodiment is denoted by the same reference numeral, and the description thereof is omitted, which is different from the first embodiment. Only the above will be described below.

That is, in the power steering apparatus according to the present embodiment, the phase-corrected shimmy variation component Sm ′ is provided between the phase correction unit 32 and the gain multiplication unit 33 in the vibration suppression signal calculation unit 22 of the electronic control unit 20. The high-pass filter 34 or the low-pass filter 35 which is the third filter according to the present invention for further adjusting the phase of the filter is interposed. Specifically, the phase difference between the phase of the vibration suppression signal T _v of the phase and shimmy fluctuation suppression torque T _vn shimmy fluctuation component Sm extracted by the band-pass filter 31 is greater than 90 degrees, and from 180 degrees In the case of being small, as shown in FIG. 6, a high-pass filter 34 is interposed between the phase correction means 32 and the gain multiplication unit 33, and the phase of the shimmy fluctuation component Sm ′ whose phase has been corrected by the high-pass filter 34. When the phase difference is larger than 180 degrees and smaller than 270 degrees, as shown in FIG. 7, the phase difference between the phase correcting means 32 and the gain multiplying unit 33 is increased. Is provided with a low-pass filter 35, and the phase of the shimmy fluctuation component Sm ′ whose phase has been corrected by the low-pass filter 35 is further delayed by a predetermined amount. It is a thing. Note that these configurations are optional, and are selected in advance according to the characteristics of the power steering apparatus related to the phase difference and set to any one of the configurations.

Hereinafter, with respect to the control content of the shimmy fluctuation suppression control of the power steering apparatus according to this embodiment having the vibration suppression signal calculation unit 22 configured as described above, the phase of the shimmy fluctuation component Sm extracted by the bandpass filter 31 and When the phase difference from the phase of the vibration suppression signal T _v related to the shimmy fluctuation suppression torque T _vn is greater than 90 degrees and smaller than 180 degrees, and when the phase difference is greater than 180 degrees and smaller than 270 degrees And will be described along the flowchart shown in FIG.

That is, in the power steering apparatus according to the present embodiment, the electronic control unit 20 reads the steering torque signal T output from the torque sensor 18 (step S21), and then based on the read steering torque signal T. Then, the torque acting on the torsion bar is calculated (step S22). Thereafter, the shimmy fluctuation component Sm is extracted by passing the calculated torsion bar torque through the bandpass filter 31 (step S23), and the phase of the shimmy fluctuation component Sm is inverted by inverting the sign of the extracted shimmy fluctuation component Sm. Is advanced by 180 degrees (step S24). Here, in the case of a power steering device having a characteristic in which the phase difference is larger than 90 degrees and smaller than 180 degrees, the shimmy fluctuation component Sm ′ subjected to the phase correction by the sign inversion is further added to the high-pass filter 34. The phase of the shimmy variation component Sm ′ is advanced by a predetermined amount through (step S25), while in the case of a power steering device having a characteristic in which the phase difference is greater than 180 degrees and smaller than 270 degrees, the sign The shimmy fluctuation component Sm ′ subjected to phase correction by inversion is further passed through the low-pass filter 35 to delay the phase of the shimmy fluctuation component Sm ′ by a predetermined amount (step S26). Thereafter, the shimmy fluctuation suppressing torque T _vn is calculated by multiplying the shimmy fluctuation component Sm ″ subjected to such phase correction by a torque conversion coefficient K (step S27), and the calculated shimmy fluctuation suppressing torque T _vn is assisted. assist torque signal T _a is a current command value to the electric motor 17 is obtained by subtracting from the steering assist torque T _an calculated in the signal calculating section 21 (step S28), and that said program is terminated Become.

  As described above, according to the power steering device according to the present embodiment, the same effects as those of the first embodiment can be obtained. In the power steering device according to the present embodiment, the band-pass filter is used. After the phase correction by the sign inversion is performed on the shimmy fluctuation component Sm extracted by 31, the phase of the shimmy fluctuation component Sm ′ is further adjusted by the high-pass filter 34 or the low-pass filter 35 for the shimmy fluctuation component Sm ′ after the phase correction. Since it is configured to adjust, even if the phase difference is not 180 degrees, the phase difference can be corrected more accurately, and the shimmy fluctuation can be further suppressed.

  9 to 12 show a third embodiment of the power steering apparatus according to the present invention, in which the configuration of the vibration suppression signal calculation unit 22 according to the first embodiment is changed. Accordingly, since the basic configuration is the same as that of the first embodiment, the same configuration as that of the first embodiment is denoted by the same reference numeral, and the description thereof is omitted, which is different from the first embodiment. Only the above will be described below.

That is, in the power steering apparatus according to this embodiment, as shown in FIG. 9, the vibration suppression signal calculation unit 22 of the electronic control unit 20 uses not only the steering torque signal T from the torque sensor 18 but also the vehicle speed sensor 19. The vehicle speed signal V is also read. Further, as shown in FIG. 10, the vibration suppression signal calculation unit 22 calculates the shimmy fluctuation component Sm ′ after the phase correction by the phase correction means 32 from the vehicle speed gain table 36 based on the read vehicle speed signal V. The shimmy variation suppression torque T _vn is calculated by multiplying the obtained gain by a torque conversion coefficient K, and the shimmy variation suppression torque T _vn is not _limited to the steering torque T _n. It is also variable depending on the vehicle speed V _n . Here, as shown in FIG. 11, when the vehicle speed V _n is less than the predetermined value X, the vehicle speed gain table 36 outputs “0” as the gain G, and the vehicle speed V _n is greater than the predetermined value X. A value proportional to the vehicle speed V _n is output as the gain G. That is, when the vehicle speed V _n is less than the predetermined value X, shimmy fluctuation does not occur. Therefore, by setting the gain G to “0”, there is no possibility of picking up other signals such as noise, and this is unnecessary. It serves to prevent the assist action from occurring. On the other hand, when the vehicle speed V _n is greater than the predetermined value X, the gain G proportional to the vehicle speed V _n is output, so that the Shimmy fluctuation increases as the vehicle speed V _n increases. It is possible to output the gain G in accordance with the above characteristic, which is used for more accurate correction of the shimmy fluctuation component Sm.

Hereinafter, the control content of the shimmy variation suppression control of the power steering apparatus according to the present embodiment having the vibration suppression signal calculation unit 22 configured as described above will be described along the flowchart shown in FIG. In the power steering apparatus according to the first embodiment, the electronic control unit 20 reads the steering torque signal T output from the torque sensor 18 (step S31), and then acts on the torsion bar based on the read steering torque signal T. Torque is calculated (step S32). Thereafter, the shimmy fluctuation component Sm is extracted by passing the calculated torsion bar torque through the bandpass filter 31 (step S33), and the phase of the shimmy fluctuation component Sm is inverted by inverting the sign of the extracted shimmy fluctuation component Sm. Is advanced 180 degrees (step S34). Then, after multiplying the shimmy fluctuation component Sm ′ subjected to such phase correction by a gain G based on the vehicle speed V _n output from the vehicle speed gain table 36 (step S35), the torque is applied to the shimmy fluctuation component SmG obtained thereby. calculating a shimmy variation suppression torque T _vn by multiplying a conversion factor K (step S36), by subtracting the calculated shimmy change suppression torque T _vn from the steering assist torque T _an calculated in the assist signal calculating section 21 in a current command value to the electric motor 17 assist torque signal T _a is obtained (step S37), so that the corresponding program is terminated.

As described above, according to the power steering device according to the present embodiment, the same effects as those of the first embodiment can be obtained. In the power steering device according to the present embodiment, the band-pass filter is used. After the phase correction by the sign inversion is performed on the shimmy fluctuation component Sm extracted by 31, the shimmy fluctuation component Sm ′ is further multiplied by a gain G corresponding to the vehicle speed Vn. phase since that is configured to adjust the ', not the steering torque T _n only, the shimmy variation suppression torque T _vn becomes possible to variable by the vehicle speed V _n, the shimmy variation varies with the vehicle speed V _n It is possible to correct the amplitude. Thereby, the said phase difference can be correct | amended more appropriately and it uses for the further suppression of a shimmy fluctuation | variation.

  The present invention is not limited to the configuration of each of the above embodiments. For example, in each of the above embodiments, the power steering device according to the present invention is set to the discharge pressure of the pump 16 that is driven and controlled by the electric motor 17. Although the example applied to the hydraulic power steering device that assists the steering force of the driver by applying the propulsive force based on the rack shaft 14 is shown, not only the hydraulic power steering device but also the electric motor 17 is shown. It is also possible to apply the present invention to an electric power steering device that assists the driver's steering force by directly applying a rotational force based on the driving force to the output shaft 13. In other words, as long as the steering assist force is generated via the electric motor 17, the power steering device itself can be freely changed according to the specifications of the vehicle to be mounted, regardless of the specific form of the power steering device itself. it can.

  Further, with respect to the predetermined value X of the third embodiment, not only the characteristics of the power steering device, but also the degree of shimmy variation changes from the relationship with the underbody of the vehicle on which the power steering device is mounted. It can be freely changed depending on the characteristics of the vehicle on which the power steering device is mounted.

Technical ideas other than those described in the respective claims ascertained from the respective embodiments will be described below.
(1) The power steering device according to claim 1 or 2, wherein each of the first oil passage and the second oil passage is constituted by a pipe formed of a rubber material.

  According to the present invention, since the pipe formed of the rubber material can be bent, the layout of the pipe can be improved and the vibration absorption can be improved by the elasticity of the rubber material.

Furthermore, by using a pipe formed of a rubber material, the phase when the steering force based on the second electric motor control signal is generated due to the expansion of the pipe is easily delayed during the hydraulic action. Alternatively, the phase correction for the predetermined frequency component related to 2 is more effective.
(2) At the time of calculating the second motor control signal, the predetermined frequency component whose phase is inverted by the second filter is multiplied by a gain corresponding to the vehicle speed, whereby the predetermined frequency is determined according to the vehicle speed. The power steering apparatus according to claim 1, wherein the power steering apparatus is configured to adjust an amplitude of a component.

According to the present invention, the amplitude of the predetermined frequency component that changes depending on the vehicle speed can be adjusted, and in combination with the phase correction of the predetermined frequency component according to claim 1 or 2, the predetermined frequency component Is subject to further reduction.
(3) The power steering apparatus according to (2), wherein the gain is set to increase as the vehicle speed increases.

According to the present invention, since the predetermined frequency component increases as the vehicle speed increases, it is possible to multiply the gain according to the characteristics of the predetermined frequency component, and to reduce the predetermined frequency component more appropriately. Can be made.
(4) The power steering device according to (2) or (3), wherein the gain is set to be zero when the vehicle speed is equal to or lower than a predetermined value.

  According to the present invention, when the vehicle speed is equal to or lower than the predetermined value, the predetermined frequency component is not generated. Therefore, when the vehicle speed is equal to or lower than the predetermined value, the gain is set to zero to pick up other signals such as noise. This is useful for preventing the occurrence of unnecessary assisting action.

22 ... Vibration suppression signal calculation unit 31 ... Band pass filter (first filter)
32: Phase correction means (second filter)
Sm ... Shimmy fluctuation component (predetermined frequency component)

Claims (2)

A power cylinder that assists the steering force of a steering mechanism linked to the steered wheels of the vehicle and has a pair of pressure chambers separated inside;
A reversible pump having a pair of discharge ports for selectively supplying hydraulic fluid to a pair of pressure chambers of the power cylinder;
A first oil passage connecting one side of the pair of pressure chambers of the power cylinder and one side of the pair of discharge ports of the reversible pump;
A second oil passage connecting the other side of the pair of pressure chambers of the power cylinder and the other side of the pair of discharge ports of the reversible pump;
An electric motor for driving the reversible pump;
A torque sensor for detecting a steering torque acting on the steering mechanism;
An electric motor control circuit for outputting an electric motor control signal for driving and controlling the electric motor;
An assist signal calculator provided in the motor control circuit for calculating a first motor control signal based on the steering torque;
A first filter for extracting a predetermined frequency component of the steering torque detected by the torque sensor;
A vibration suppression signal calculation unit that is provided in the motor control circuit and calculates a second motor control signal that reduces the predetermined frequency component;
The difference between the phase when the predetermined frequency component is generated and the phase when the steering force based on the second electric motor control signal is generated in the power cylinder is larger than 90 degrees and smaller than 270 degrees A power steering device,
Providing a second filter that outputs a phase inversion signal for inverting the phase of the predetermined frequency component;
The power steering apparatus, wherein the vibration suppression signal calculation unit is configured to calculate the second motor control signal based on a phase inversion signal of the predetermined frequency component. The power steering apparatus according to claim 1, further comprising a third filter that changes a phase of the predetermined frequency component so that a residual phase difference obtained by subtracting 180 degrees from the phase difference decreases.

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