JP2017124741A - Adjusting method for steering device and adjusting device for steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adjusting method for steering device and an adjusting device for steering device such that a clearance between a support yoke and a yoke plug can be set more suitably.SOLUTION: A yoke plug 22 temporarily fastened enough to cause a support yoke to elastically have compressive deformation is unfastened up to an angle position θ1 in a stable region where displacement E does not change in a direction crossing the axis of a rack shaft 12 against variation in angle position θ of the yoke plug 22. At this time, an inflection point Pi as a border point where a rate of variation in displacement E of the rack shaft 12 to variation in angle position θ of the yoke plug 22 abruptly decreases is found, and a target angle position θ3 corresponding to a target clearance is set based upon an angle position θ2 corresponding to the inflection point Pi. Then, after the yoke plug 22 is unfastened again up to the target angle position θ3 after the yoke plug 22 is unfastened up to an angle position θ4, the yoke plug 22 is unfastened up to the target angle position θ3.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a steering device adjustment method and a steering device adjustment device.

  Conventionally, as described in Patent Document 1, for example, a rack and pinion type steering device is known. The steering device includes a pinion shaft that rotates in conjunction with the steering wheel, a rack shaft that meshes with the pinion shaft, and a housing that houses both the shafts. As the pinion shaft rotates, the rack shaft moves in its own axial direction to change the direction of the wheels.

  In addition, the steering device includes a support mechanism for removing backlash between the rack shaft and the pinion shaft. The support mechanism includes a support yoke that can be moved forward and backward in the holding hole of the housing, a yoke plug that is screwed into the holding hole, and a compression coil spring that is interposed between the yoke plug and the support yoke. The support yoke is constantly biased toward the rack shaft by the elastic force of the compression coil spring. The rack is supported by the support yoke so as to be slidable along its own axial direction, and is pressed toward the pinion.

  A predetermined amount of clearance is provided between the support yoke and the yoke plug in order to suppress the hitting sound caused by the contact between the support yoke and the yoke plug. The clearance is strictly controlled, and is adjusted, for example, as follows. That is, first, the yoke plug is temporarily tightened in the holding hole to such an extent that the yoke plug contacts the support yoke. Thereafter, the yoke plug is loosened until the clearance reaches the target clearance.

JP 2008-018828 A

  However, in the above-described clearance adjustment method, there are concerns about the following. That is, it is preferable to adjust the clearance with reference to the zero clearance position where the yoke plug just contacts the support yoke, but it is not certain whether the yoke plug is at the true zero clearance position. Also, when the yoke plug is temporarily tightened, the zero clearance position may vary from product to product. As the zero clearance position varies, the adjusted clearance also varies.

  An object of the present invention is to provide a steering device adjustment method and a steering device adjustment device capable of more appropriately setting a clearance between a support yoke and a yoke plug.

  The adjustment method of the steering device that can achieve the above-described object includes a rack shaft that linearly moves inside the housing, a pinion shaft that is rotatably supported by the housing and meshes with the rack shaft, and a guide hole provided in the housing A support yoke that is slidably supported in the rack shaft and slidably supports the rack shaft along its axial direction, a yoke plug that is screwed into the guide hole, and the yoke plug and the support. It is assumed that the steering device has a biasing member that is interposed between the yoke and biases the support yoke toward the rack shaft. In addition, when the yoke plug temporarily tightened to such an extent that elastic compression deformation occurs in the support yoke, the rack shaft with respect to the housing as a reference with respect to the change in the angular position of the yoke plug. The yoke plug is loosened to an angular position where the clearance between the support yoke and the yoke plug reaches a target clearance with reference to an angular position that becomes a boundary at which the rate of change in displacement in the direction intersecting the axis rapidly decreases.

  When loosening the temporarily tightened yoke plug to the extent that elastic compression deformation occurs in the support yoke, the displacement in the direction intersecting with the axis of the rack shaft is first performed as the compression deformation of the support yoke is released. Decreases linearly as the angular position of the yoke plug increases. At this time, the change rate of the displacement of the rack shaft is substantially constant. After the compression deformation of the support yoke is released, the rate of change in rack shaft displacement with respect to the increase in the angular position of the yoke plug decreases rapidly, and eventually the rack shaft displacement basically increases in the angular position of the yoke plug. On the other hand, it will not change.

  Based on this, according to the above adjustment method, the angular position that becomes the boundary where the rate of change of the rack shaft displacement rapidly decreases with respect to the change in the angular position of the yoke plug, that is, the compression deformation of the support yoke is released. The yoke plug is loosened to the angular position where the clearance reaches the target clearance with reference to the angular position (so-called zero clearance position). For this reason, a more appropriate clearance approximate to the target clearance can be set.

  The method for adjusting the steering device is preferably performed as follows. That is, after loosening the yoke plug to an angular position at which the displacement of the rack shaft does not change with respect to a change in the angular position of the yoke plug, a target corresponding to the target clearance with the angular position serving as the boundary as a reference Set the angular position. Next, after the yoke plug is tightened to an angular position that is at least less than the target angular position, the yoke plug is again loosened to the target angular position.

  For example, it is conceivable that the influence of the mechanical rattling differs between when the yoke plug is tightened and when the yoke plug is loosened. For this reason, it is preferable to adjust to the target angular position while loosening the yoke plug, as in the case of setting the target angular position, as in the above adjustment method. In this way, when adjusting the clearance, the influence of mechanical rattling on the clearance is suppressed. For this reason, a more accurate clearance can be ensured.

  In the steering apparatus adjustment method described above, the angular position serving as the boundary includes an approximate straight line that is set along a change tendency of the displacement of the rack shaft before a rapid decrease, and the rack shaft after the sudden decrease. It is preferable to detect the angular position corresponding to the intersection with the approximate straight line set along the change tendency of the displacement.

According to this adjustment method, it is possible to easily detect an angular position that becomes a boundary at which the change rate of the displacement of the rack shaft rapidly decreases.
The steering device adjustment method is performed using, for example, the following steering device adjustment device. The adjusting device includes a motor, a rotating socket that rotates integrally with the yoke plug in conjunction with the motor, a rotation sensor for detecting an angular position of the yoke plug, and the rack based on the housing. It is preferable to have a displacement sensor that detects displacement in a direction intersecting the axis of the shaft, and a control device that controls the motor based on the detection result of the rotation sensor and the displacement sensor.

According to this adjusting device, the above-described method for adjusting the steering device can be suitably executed.
In the steering device adjusting apparatus, in the case where the guide hole is provided to be biased to one side of the two end portions of the housing, the displacement sensor is the one of the housings on the rack shaft. It is preferable to detect the displacement of the measurement point set in the portion protruding from the end of the.

  When the yoke plug is temporarily tightened to such an extent that elastic compression deformation occurs in the support yoke, the rack shaft is slightly displaced in the direction intersecting the axis due to distortion of the pinion shaft or the like. This displacement is greater at the end near the portion of the rack shaft that is pressed against the pinion shaft than at the far end. As with the adjustment device described above, the rack shaft displacement can be suitably detected by setting the measurement point at a portion where the rack shaft is more easily displaced.

  According to the steering device adjustment method and the steering device adjustment device of the present invention, the clearance between the support yoke and the yoke plug can be set more appropriately.

Sectional drawing which shows one Embodiment of a steering device. The front view which shows an example of the adjustment apparatus of a steering device. The block diagram which shows an example of the electrical structure of the adjustment apparatus of a steering device. The flowchart which shows an example of the adjustment procedure of a steering device. The graph which shows an example of the relationship between the angle position of a yoke plug, and the displacement in the direction which cross | intersects the axis line of a rack shaft. (A) is a cross-sectional view of the main part of the steering device showing the support yoke compressed as the yoke plug is tightened, and (b) is a main part of the steering device showing the state where the yoke plug is held at the zero clearance position. Sectional drawing, (c) is a principal part sectional view of a steering device showing a state where a clearance is formed between a yoke plug and a support yoke.

Hereinafter, an embodiment of the steering device will be described.
<Schematic configuration of steering device>
As shown in FIG. 1, the steering device 10 includes a housing 11 that is fixed to the vehicle body. A rack shaft 12 is inserted into the housing 11. The rack shaft 12 is supported so as to be movable relative to the housing 11 along its axial direction (direction orthogonal to the paper surface). Further, a pinion shaft 13 extending along a direction intersecting with the rack shaft 12 (vertical direction in the drawing) is inserted into the housing 11. The pinion shaft 13 is rotatably supported with respect to the housing 11 via a bearing 14. The pinion shaft 13 rotates in conjunction with the operation of a steering wheel (not shown). As the pinion shaft 13 rotates, the rack shaft 12 moves in the axial direction to change the direction of the wheels (not shown).

  Further, in the housing 11, a cylindrical guide hole 15 extending along a direction orthogonal to the rack shaft 12 (left and right direction in the drawing) is provided at a portion opposite to the pinion shaft 13 sandwiching the rack shaft 12. Is provided. The guide hole 15 opens to the outside of the housing 11. On the inner peripheral surface of the guide hole 15, a female screw portion 16 is provided at the end on the opening side. A support mechanism 20 for pressing the rack shaft 12 against the pinion shaft 13 is provided inside the guide hole 15.

  The support mechanism 20 includes a support yoke 21 that slidably supports the peripheral surface of the rack shaft 12, a yoke plug 22 that is screwed into the female screw portion 16 of the guide hole 15, and a space between the support yoke 21 and the yoke plug 22. And a compression coil spring 23 as an urging member interposed therebetween.

  The support yoke 21 is provided in a cylindrical shape with a metal material such as aluminum. The support yoke 21 moves forward and backward along the depth direction of the guide hole 15. The outer peripheral surface of the support yoke 21 is guided by sliding with respect to the inner peripheral surface of the guide hole 15. Two annular grooves 24, 24 are provided on the outer peripheral surface of the support yoke 21. O-rings 25 and 25 are mounted in the grooves 24 and 24, respectively. These O-rings 25 and 25 seal between the inner peripheral surface of the guide hole 15 and the outer peripheral surface of the support yoke 21 by elastic contact with the inner peripheral surface of the guide hole 15. The O-rings 25 and 25 elastically support the support yoke 21 in the radial direction. Thereby, rattling of the support yoke 21 is suppressed.

  A concave surface (arc surface) 26 along the circumferential surface of the rack shaft 12 is provided on the side surface (left side surface in the drawing) of the support yoke 21 on the rack shaft 12 side. A sheet 27 that is in sliding contact with the rack shaft 12 is attached to the concave surface 26. The sheet 27 is formed of a metal material such as bronze, for example.

  A spring accommodation hole 28 is provided on the side surface (right side surface in the drawing) of the support yoke 21 opposite to the rack shaft 12. One end (left end portion in the figure) of the compression coil spring 23 is inserted into the spring accommodating hole 28. Thereby, it is suppressed that the compression coil spring 23 moves to the radial direction. The support yoke 21 is directed toward the rack shaft 12 by the elastic force of the compression coil spring 23 interposed between the inner bottom surface of the spring accommodating hole 28 and the side surface (left side surface in the figure) of the yoke plug 22 on the support yoke 21 side. Always energized. The concave surface 26 is slidably pressed against the peripheral surface of the rack shaft 12 via the seat 27.

  The yoke plug 22 is provided in a columnar shape by a metal material such as steel. A cylindrical surface 22 a and a male screw portion 22 b are provided on the outer peripheral surface of the yoke plug 22 in order from the side close to the support yoke 21. An annular groove 29 is provided in the cylindrical surface 22a. An O-ring 30 is attached to the groove 29.

  An engagement hole 31 is provided on the side surface (the right side surface in the figure) of the yoke plug 22 opposite to the support yoke 21. The engagement hole 31 engages with a tool (not shown) for rotating the yoke plug 22. The shape of the engagement hole 31 may be an appropriate shape such as a hexagonal shape or a dodecagonal shape depending on the tool shape. The yoke plug 22 is fixed to the housing 11 by fastening the male screw portion 22b to the female screw portion 16 while inserting the end portion on the side where the cylindrical surface 22a is provided into the guide hole 15.

  A clearance C is formed between the side surface of the support yoke 21 on the yoke plug 22 side (right side surface in the drawing) and the side surface of the yoke plug 22 on the support yoke 21 side (left side surface in the drawing). The amount of clearance C is strictly managed through adjustment of the screwing position of the yoke plug 22.

<Clearance adjustment device>
The clearance C is adjusted using, for example, the following adjusting device. The adjustment device is used in the adjustment process of the clearance C, which is a part of the assembly process of the steering device 10.

  As shown in FIG. 2, the adjustment device 40 includes a base 41, two support legs 42 and 42 that are provided on the base 41 and support the steering device 10, a drive unit 43 that rotates the yoke plug 22, And a linear gauge 44 as a displacement sensor.

  The two support legs 42, 42 support both end portions of the housing 11 in the steering device 10 that is assembled in advance. At this time, the steering device 10 is maintained in a posture in which, for example, the guide hole 15 faces the side opposite to the base 41 (upper side in the drawing). Here, the direction in which the axis O of the guide hole 15 extends coincides with the direction of gravity.

  The drive unit 43 is provided, for example, on a frame (not shown) that constitutes the framework of the adjustment device 40. Further, as indicated by a white arrow in the drawing, the drive unit 43 moves along an elevating direction D, which is a direction approaching or separating from the base 41 through the operation of an elevating mechanism (not shown).

  The drive unit 43 includes a motor 51, a drive gear 53 fixed to the output shaft 52 of the motor 51, a driven gear 54 that meshes with the drive gear 53, and a rotary socket 55 connected to the driven gear 54. Yes. The motor 51 is provided with a rotation sensor 56. The driven gear 54 is provided at an end portion (upper end portion in the figure) of the rotary socket 55 on the side opposite to the base 41. An engagement protrusion 57 that functions as a tool that engages with the engagement hole 31 of the yoke plug 22 is provided at the end (lower end in the drawing) of the rotary socket 55 on the base 41 side. As the shape of the engagement protrusion 57, an appropriate shape such as a hexagonal column shape or a dodecagonal column shape corresponding to the shape of the engagement hole 31 is adopted. When adjusting the clearance C, the drive unit 43 is lowered and the engagement protrusion 57 is inserted into the engagement hole 31 of the yoke plug 22. As a result, the yoke plug 22 can rotate integrally with the rotary socket 55. This is because the engagement protrusion 57 engages with the engagement hole 31 in the rotation direction.

The linear gauge 44 includes a case 61 supported by the housing 11, a spindle 62 protruding from the case 61, and a detector 63 provided inside the case 61.
Here, the guide hole 15 is provided at a position offset from the first end portion 11a and the second end portion 11b of the housing 11 toward the first end portion 11a side (left side in FIG. 2). The first end portion 12 a of the rack shaft 12 protrudes from the first end portion 11 a of the housing 11, and the second end portion 12 b of the rack shaft 12 protrudes from the second end portion 11 b of the housing 11. Based on this premise, the case 61 is supported by the housing 11 via a support member 64 fixed to the first end portion 11 a of the housing 11. The case 61 is opposed to the first end 12a of the rack shaft 12 protruding from the first end 11a of the housing 11 in the direction along the axis O of the guide hole 15 (vertical direction in FIG. 2). doing.

  The spindle 62 extends along the axis O of the guide hole 15 and can advance and retreat with respect to the case 61 in a direction along the axis O of the guide hole 15. The tip end portion (the lower end portion in FIG. 2) of the spindle 62 is maintained in a state of being in contact with the peripheral surface of the rack shaft 12 by gravity. The portion of the peripheral surface of the rack shaft 12 with which the spindle 62 abuts is a measurement point Pm that serves as a reference position when detecting displacement in the direction along the axis O of the guide hole 15 of the rack shaft 12.

  As indicated by a two-dot chain line in FIG. 2, for example, when the rack shaft 12 is tilted counterclockwise, the first end portion 12a of the rack shaft 12 approaches the base 41 (FIG. 2). When displaced toward the lower middle), the spindle 62 extends relative to the case 61 by gravity. Further, when the rack shaft 12 is inclined in the clockwise direction, the spindle 62 is displaced when the first end portion 12a of the rack shaft 12 is displaced in a direction away from the base 41 (upward in FIG. 2). Is pressed against the rack shaft 12 and enters relatively to the case 61 against gravity.

  The detector 63 generates an electrical signal corresponding to the position of the spindle 62 with respect to the case 61. Since the case 61 is supported by the housing 11, the change in the position of the spindle 62 relative to the case 61 is equal to the change in the position of the rack shaft 12 relative to the housing 11.

<Electrical configuration of adjusting device>
Next, the electrical configuration of the adjusting device 40 will be described.
As shown in FIG. 3, the adjustment device 40 includes a control device 71 and a monitor 72. The control device 71 comprehensively controls each part of the adjustment device 40. The rotation sensor 56 and the linear gauge 44 (more precisely, the detector 63) are connected to the control device 71, respectively. Further, a motor 51 and a monitor 72 are connected to the control device 71, respectively. The monitor 72 displays various information through display control by the control device 71.

  The control device 71 controls driving of the motor 51. Further, the control device 71 calculates the amount of rotation of the motor 51 and thus the angular position θ of the yoke plug 22 with respect to the housing 11 based on the electrical signal generated by the rotation sensor 56. Further, the control device 71 calculates the displacement E of the rack shaft 12 relative to the housing 11 in the direction along the axis O of the guide hole 15 based on the electrical signal generated by the linear gauge 44. The control device 71 executes clearance C adjustment processing based on the relationship between the angular position θ of the yoke plug 22 and the displacement E of the rack shaft 12. When executing the adjustment process of the clearance C, the control device 71 causes the monitor 72 to display a graph indicating the relationship between the angular position θ of the yoke plug 22 and the displacement E of the rack shaft 12.

<Clearance adjustment method>
Next, a method for adjusting the clearance C will be described. The control device 71 executes clearance C adjustment processing according to a control program stored in a storage device (not shown). The adjustment process is one step in each assembly process of the steering device.

  The steering device 10 is set between the two support legs 42 and 42 of the adjusting device 40 in a state where the yoke plug 22 is temporarily fastened to the guide hole 15 in advance. At this time, the yoke plug 22 is maintained in contact with the support yoke 21. Here, although the clearance C between the yoke plug 22 and the support yoke 21 is “0”, the yoke plug 22 is tightened to the zero clearance excess position beyond the zero clearance position (zero touch position). It is conceivable that 21 is elastically compressed. Here, it is assumed that the support yoke 21 is temporarily tightened to such an extent that elastic compression deformation occurs.

  Incidentally, as shown in FIG. 6A, the zero clearance excess position means that the axial force (pressing force) of the yoke plug 22 is reduced by the tightening even after the yoke plug 22 contacts the support yoke 21. 21 refers to the position where it acts on 21 and undergoes compressive deformation. At this time, the axial force F of the yoke plug 22 acts on the pinion shaft 13 via the rack shaft 12, so that the pinion shaft 13 is distorted. Further, due to the occurrence of distortion in the pinion shaft 13, the rack shaft 12 is directed toward the direction in which the axial force F of the yoke plug 22 acts on the housing 11 (downward in FIG. 6A). Slight displacement. That is, the rack shaft 12 is slightly tilted from the normal position indicated by the solid line in FIG. 2 to the tilt position indicated by the two-dot chain line in FIG. The normal position refers to an original attachment position of the rack shaft 12 with respect to the housing 11 in a state where the axial force F of the yoke plug 22 is not applied.

  Further, as shown in FIG. 6B, the zero clearance position is a position where the yoke plug 22 is just in contact with the support yoke 21 and the axial force F of the yoke plug 22 does not act on the support yoke 21 and is compressed. A position where no deformation occurs. At this time, the pinion shaft 13 is not distorted. Further, the rack shaft 12 is held at a normal position indicated by a solid line in FIG.

In this example, when the yoke plug 22 at the zero clearance excess position is loosened, the zero clearance position of the yoke plug 22 is determined based on the position change of the rack shaft 12 with respect to the housing 11 (position change from the tilt position to the normal position). Ask. Then, the clearance C between the support yoke 21 and the yoke plug 22 shown in FIG. 6C is adjusted to the target clearance C ^{* based} on the calculated zero clearance position.

  As shown in the flowchart of FIG. 4, the control device 71 first moves the motor 51 in a direction to loosen the yoke plug 22 from a state where the yoke plug 22 is temporarily tightened to such an extent that elastic compression deformation occurs in the support yoke 21. Drive (step S101). The rotation speed of the motor 51, that is, the rotation speed of the yoke plug 22 is a constant speed.

  FIG. 5 is a graph showing the relationship between the angular position θ of the yoke plug 22 with respect to the housing 11 and the displacement E of the rack shaft 12 (precisely, the measurement point Pm) with respect to the housing 11. In the graph, the angular position θ of the yoke plug 22 indicates that a change in the negative direction tightens the yoke plug 22, and a change in the positive direction indicates that the yoke plug 22 is loosened. In the graph, the change in the angular position θ in the positive direction is referred to as an increase in the angular position θ, and the change in the angular position θ in the negative direction is referred to as a decrease in the angular position θ. In the graph, the displacement E of the rack shaft 12 indicates that a change in the positive direction decreases the displacement of the rack shaft 12, and a change in the negative direction indicates that the displacement of the rack shaft 12 increases. .

  As shown by the black arrow in the graph of FIG. 5, as the angular position θ of the yoke plug 22 increases from the angular position θ0 at the time of temporary fastening, the change gradient of the displacement E of the rack shaft 12 is We gradually increase to draw a gentle curve, and eventually become constant. In other words, the displacement E gradually decreases so as to draw a gentle curve as the angular position θ increases, and then gradually decreases so as to draw a straight line with a constant inclination. Further, when the yoke plug 22 is loosened, the change gradient of the displacement E of the rack shaft 12 with respect to the increase of the angular position θ decreases rapidly so as to draw a curve, and eventually reaches “0” (ideal state). When the change gradient of the displacement E is “0”, the displacement E becomes constant without changing with respect to the increase in the angular position θ.

  The increase in the displacement E of the rack shaft 12 due to the increase in the angular position θ between the start of loosening the yoke plug 22 and the change in the displacement E of the rack shaft 12 results in compressive deformation (distortion) of the support yoke 21 and consequently. This is because the distortion of the pinion shaft 13 is released. Depending on the degree of compressive deformation of the support yoke 21 and the release of the distortion of the pinion shaft 13, the rack shaft 12 is gradually moved from the inclined position indicated by the two-dot chain line in FIG. 2 to the normal position indicated by the solid line in FIG. Return. For this reason, when the displacement E of the rack shaft 12 becomes constant with respect to the increase in the angular position θ, that is, the change gradient of the displacement E becomes “0”, the compression deformation of the support yoke 21, and consequently the pinion shaft 13. Indicates that the strain is released.

  As shown in the flowchart of FIG. 4, the controller 71 makes the displacement E of the rack shaft 12 constant with respect to the increase in the angular position θ while driving the motor 51 in the direction of loosening the yoke plug 22 through the previous step S101. It is determined that a stable state has been reached (step S102).

  As the determination method of the stable state, for example, the following two methods can be considered. First, as a first determination method, the control device 71 may detect that the yoke plug 22 has reached a stable state by detecting that the yoke plug 22 has been loosened to a predetermined angular position θ1. The angular position θ1 is set based on the obtained angular position θ by obtaining the angular position θ when the displacement E of the rack shaft 12 does not change with an increase in the angular position θ by, for example, experiments. Next, as a second determination method, the control device 71 monitors a change in the displacement E of the rack shaft 12 with respect to the increase in the angular position θ, and a period in which the displacement E of the rack shaft 12 with respect to the increase in the angular position θ is constant. When the (period in which the change in the displacement E is within the threshold range) continues for a set period, it may be detected that a stable state has been reached. In this example, when the yoke plug 22 is loosened to the angular position θ1, it is detected that a stable state has been reached.

  When it is detected in step S102 that the stable state has been reached, the controller 71 calculates the inflection point Pi (step S103). The inflection point Pi is a boundary point where the change gradient of the displacement E of the rack shaft 12 changes with respect to the change of the angular position θ.

  The control device 71 obtains two regression lines (approximate straight lines) L1 and L2 indicated by broken lines in the graph of FIG. 5 by, for example, the least square method based on the displacement E of the rack shaft 12 and the angular position θ. The regression line L1 indicates a change tendency of the displacement E of the rack shaft 12 in the compression region where the axial force F of the yoke plug 22 acts on the support yoke 21. The regression line L2 indicates the displacement E in the stable region (non-compressed region) where the compression deformation of the yoke plug 22 and the distortion of the pinion shaft 13 are released, and the displacement E of the rack shaft 12 is constant with respect to the increase in the angular position θ. Indicates a change trend. Here, the regression line L2 is a straight line having an inclination of 0 (zero) represented by “L2 = Emin (constant)”. The control device 71 calculates the intersection of these regression lines L1 and L2 as the inflection point Pi, and temporarily stores the angular position θ2 corresponding to the calculated inflection point Pi. When the angular position θ of the yoke plug 22 is the angular position θ2 corresponding to the inflection point Pi, it can be said that the yoke plug 22 is positioned at the zero clearance position.

  The regression line L1 may be obtained as follows. That is, the value of the displacement E of the region that changes more linearly is used in the locus of the displacement E that decreases as the angular position θ increases. For example, the control device 71 sets a value of 20% of the displacement Emax at the time of temporary fastening as an upper limit value E1 of the setting range and a value of 80% of the displacement Emax at the time of temporary fastening as a lower limit value E2 of the setting range. The regression line L1 is calculated using the value of the displacement E within the set range defined by the value E1 and the lower limit value E2. These upper limit value E1 and lower limit value E2 may be set in advance by experiments or the like.

As shown in the flowchart of FIG. 4, the control device 71 calculates the target angle position θ3 after calculating the inflection point Pi in the previous step S103 (step S104). The target angular position θ3 is obtained by adding a predetermined rotation amount (rotational angle) δθc to the angular position θ2 corresponding to the inflection point Pi. The rotation amount δθc is a rotation amount required to move the yoke plug 22 in the axial direction by the target clearance C ^* when the yoke plug 22 is loosened.

Next, the control device 71 drives the motor 51 in a direction to tighten the yoke plug 22 this time (step S105).
Specifically, as shown in the graph of FIG. 5, the timing at which it is detected that a stable state in which the displacement E of the rack shaft 12 is constant with respect to the increase in the angular position θ is detected, that is, the yoke plug 22 is inflected. Tightening of the yoke plug 22 is started at a timing at which the angle position θ1 is larger than the angular position θ2 corresponding to the point Pi. As shown in the graph of FIG. 5 with a shaded arrow, the displacement of the rack shaft 12 during the period from the angular position θ1 to the angular position θ2 (<θ1) corresponding to the inflection point Pi. E is substantially constant regardless of the change (decrease) in the angular position θ.

  This is for the following reason. That is, when the angular position θ of the yoke plug 22 is the angular position θ2 corresponding to the inflection point Pi, it is estimated that the yoke plug 22 is positioned at the zero clearance position. Therefore, when the angular position θ of the yoke plug 22 is larger than the angular position θ2, a clearance C corresponding to the angular position θ is naturally formed between the support yoke 21 and the yoke plug 22. For this reason, when the yoke plug 22 positioned at the angular position θ1 is tightened, the clearance C gradually decreases according to the tightening degree. Since the axial force F accompanying the tightening of the yoke plug 22 does not act on the support yoke 21, the pinion shaft 13 is not distorted, and the displacement E of the rack shaft 12 does not change.

  As shown in the flowchart of FIG. 4, the control device 71 then confirms that the yoke plug 22 has been tightened by a set angle δθt (for example, about 20 °) with reference to the angular position θ2 corresponding to the inflection point Pi. Detect (S106).

  As shown in the graph of FIG. 5, the angular position θ of the yoke plug 22 at this time is larger than the angular position θ0 at the time of temporary tightening and is smaller than the angular position θ2 corresponding to the inflection point Pi. The position θ4. At this time, when the yoke plug 22 is tightened beyond the zero clearance position, the axial force F of the yoke plug 22 is transmitted to the rack shaft 12 and eventually the pinion shaft 13 via the support yoke 21 according to the tightening amount. The For this reason, the pinion shaft 13 starts to be distorted again. Therefore, the displacement E of the rack shaft 12 gradually increases as the angular position θ decreases as the yoke plug 22 is tightened.

  As shown in the flowchart of FIG. 4, when it is detected in step S106 that the yoke plug 22 is tightened by the set angle δθt, the control device 71 drives the motor 51 again in the direction of loosening the yoke plug 22 (S107). ). When it is detected that the angular position θ of the yoke plug 22 has reached the target angular position θ3 (step S108), the control device 71 stops the motor 51 (step S109). The clearance C adjustment process is thus completed.

  As shown in the graph of FIG. 6 with a white arrow, at the beginning, the angular position θ of the yoke plug 22 starts to increase starting from the angular position θ4. Although it is constant, it begins to decrease gradually. This is because the amount of compressive deformation of the support yoke 21 is smaller than that during temporary fastening. The displacement E of the rack shaft 12 increases from the angular position θ to the target angular position θ3 after the angular position θ of the yoke plug 22 reaches a value near the angular position θ2 corresponding to the inflection point Pi. Along with this, it changes along the locus of the displacement E when the yoke plug 22 shown with a black arrow in the graph of FIG. 5 is first loosened from the temporarily tightened state.

  Note that the yoke plug 22 is finally fixed to the housing 11. When the self-locking type yoke plug 22 is used, when the adjustment of the clearance C is completed, the fixing to the housing 11 is also completed. The self-locking type is a type in which the threaded portion is fixed by friction generated by tightening the threaded portion formed on the outer peripheral surface of the yoke plug 22 having a non-circular cylindrical shape. Further, when the yoke plug 22 having no self-locking function is adopted, after the adjustment operation of the clearance C is completed, the yoke plug 22 is fixed to the housing 11 by caulking the yoke plug 22 or applying an adhesive. To do. Thus, the assembly work of the steering device 10 is completed.

<Operation and Effect of Embodiment>
Therefore, according to the present embodiment, the following actions and effects can be obtained.
(1) When the yoke plug 22 temporarily tightened to such an extent that elastic compression deformation occurs in the support yoke 21, the rate of change of the displacement E of the rack shaft 12 with respect to the change of the angular position θ of the yoke plug 22 is abrupt. An inflection point Pi, which is a boundary point that decreases to, is obtained. Then, with reference to the angular position θ2 corresponding to the inflection point Pi, the yoke plug 22 is loosened to the target angular position θ3 where the clearance C reaches the target clearance C ^* . Here, the angular position θ2 at which the rate of change of the displacement E of the rack shaft 12 rapidly decreases indicates the true zero clearance position of the yoke plug 22 where the compressed state of the support yoke 21 is released. By using this true zero clearance position as a reference, a more appropriate clearance C approximate to the target clearance C ^* can be set. Variations in the clearance C between products can also be suppressed.

  (2) The inflection point Pi, which is a boundary point at which the rate of change of the displacement E with respect to the change of the angular position θ rapidly decreases, is, for example, two regression lines obtained by the least square method based on the displacement E and the angular position θ. It is detected as a position corresponding to the intersection of L1 and L2. The regression line L1 is an approximate line that is set along the change tendency of the displacement E before the change rate of the displacement E with respect to the change of the angular position θ rapidly decreases. The regression line L2 is an approximate line that is set along the change tendency of the displacement E after the change rate of the displacement E with respect to the change of the angular position θ rapidly decreases. In this way, the inflection point Pi can be easily detected.

(3) Here, when calculating the inflection point Pi, the yoke plug 22 is loosened to the angular position θ1 in the stable region where the displacement E of the rack shaft 12 does not change with respect to the change in the angular position θ of the yoke plug 22. A more accurate inflection point Pi can be calculated. The fact that the displacement E of the rack shaft 12 does not change indicates that the axial force F against the support yoke 21 and the distortion of the pinion shaft 13 are released. Therefore, it is possible to calculate a more accurate regression line L2 based on the angular position θ1 of the stable region and the displacement E of the rack shaft 12 with respect to the angular position θ1 of the stable region. By using a more accurate regression line L2, a more accurate inflection point Pi can be calculated. Further, the angle position θ2 corresponding to the inflection point Pi indicates the true zero clearance position of the yoke plug 22. Therefore, a more accurate clearance C is set by setting a target angular position θ3 corresponding to the target clearance C ^* with the angular position θ2 as a reference, and matching the angular position θ of the yoke plug 22 with the target angular position θ3. be able to.

  (4) When the angular position θ of the yoke plug 22 is matched with the target angular position θ3, the angular position of the yoke plug 22 that exceeds the angular position θ2 corresponding to the inflection point Pi from the angular position θ1 of the stable region in the negative direction. By tightening to θ4 and then loosening the yoke plug 22 to the target angular position θ3, a more accurate clearance C can be secured. This is for the following reason. For example, it is conceivable that the influence of mechanical rattling inherent in the steering device 10 or the adjusting device 40 differs depending on whether the yoke plug 22 is tightened or loosened. For this reason, it is preferable to adjust to the target angular position θ3 while loosening the yoke plug 22 as in the case of calculating the inflection point Pi. In this way, the influence of the mechanical rattling of the steering device 10 or the adjusting device 40 on the clearance C can be suppressed.

  (5) Since a more accurate zero clearance position (inflection point Pi) is known, the clearance C can be set to a value as large as possible within a permissible range and pinpointed. When the clearance C is narrow, the required steering torque may increase. In this regard, it is possible to suppress an increase in steering torque by expanding the clearance to near the limit of the allowable range.

(6) Further, by using a more accurate zero clearance position as a reference, the clearance C can be adjusted more easily and more quickly.
(7) The spindle 62 of the linear gauge 44 is kept in contact with the peripheral surface of the rack shaft 12 by gravity. The contact state between the spindle 62 and the rack shaft 12 is not affected by the compression deformation of the support yoke 21. Since the stable contact state between the spindle 62 and the rack shaft 12 is maintained, the displacement E of the rack shaft 12 can be detected more accurately.

  (8) Further, the contact state between the spindle 62 and the rack shaft 12 is not affected by the elastic force of the compression coil spring 23. For this reason, the compression coil spring 23 having higher elasticity can be employed. When the rack shaft 12 is more strongly pressed against the pinion shaft 13, rattling at the meshing portion between the rack shaft 12 and the pinion shaft 13 is suitably suppressed. Therefore, the abnormal noise generated due to the rattling is more effectively suppressed.

  (9) When displaying the graph shown in FIG. 5 on the monitor 72, the operator visually indicates the displacement E of the rack shaft 12 with respect to the angular position θ of the yoke plug 22 and the zero clearance position (inflection point Pi). Can be confirmed.

<Other embodiments>
In addition, you may implement this Embodiment as follows.
In this example, the contact-type linear gauge 44 that contacts the spindle 62 with the rack shaft 12 is used as the displacement sensor, but any type can be used as long as the displacement E of the rack shaft 12 can be measured with the required accuracy. The displacement sensor may be used. Various displacement sensors such as a magnetic type, an optical type, a contact type, or a non-contact type can be employed.

In this example, when the inflection point Pi is obtained, the regression lines L1 and L2 are obtained by the least square method, but other methods such as principal component analysis may be used.
In this example, when the angular position θ of the yoke plug 22 is matched with the target angular position θ3, the angular position of the yoke plug 22 that exceeds the angular position θ2 corresponding to the inflection point Pi from the angular position θ1 of the stable region in the negative direction. Although tightening is performed up to θ4, the tightening may be performed to at least the target angle position θ3 in the negative direction.

  It is also possible to construct an electric power steering device (EPS) by providing the steering device 10 with an assist motor that is a source of steering assist force. Further, not only the electric power steering apparatus but also a steer-by-wire system or an automatic steering system can be applied as an actuator for turning steered wheels.

DESCRIPTION OF SYMBOLS 10 ... Steering device, 11 ... Housing, 11a ... First end of housing, 11b ... Second end of housing, 12 ... Rack shaft, 12a ... First end of rack shaft, 12b ... Rack shaft Second end, 13 ... pinion shaft, 15 ... guide hole, 21 ... support yoke, 22 ... yoke plug, 23 ... compression coil spring (biasing member), 40 ... adjusting device, 44 ... linear gauge (displacement sensor) , 51, motor, 55, rotating socket, 56, rotation sensor, 71, control device, C, clearance, C ^*, target clearance, E, rack shaft displacement, L 1, regression line (first approximate line), L 2 ... regression line (second approximate line), Pi ... inflection point (intersection point), Pm ... measurement point, θ ... angular position of yoke plug.

Claims (5)

A rack shaft that linearly moves inside the housing;
A pinion shaft that is rotatably supported by the housing and meshes with the rack shaft;
A support yoke that is slidably received in a guide hole provided in the housing and supports the rack shaft slidably along the axial direction;
A yoke plug fixed in a state of being screwed into the guide hole;
A biasing member interposed between the yoke plug and the support yoke and biasing the support yoke toward the rack shaft;
When loosening the yoke plug temporarily tightened to such an extent that elastic compression deformation occurs in the support yoke, the axis of the rack shaft with respect to the housing relative to the change in the angular position of the yoke plug Adjustment of the steering device that loosens the yoke plug to an angular position at which the clearance between the support yoke and the yoke plug reaches a target clearance on the basis of the angular position that becomes a boundary at which the rate of change of displacement in the intersecting direction sharply decreases Method. In the adjustment method of the steering device according to claim 1,
After the yoke plug is loosened to an angular position at which the displacement of the rack shaft does not change with respect to a change in the angular position of the yoke plug, a target angular position corresponding to the target clearance with the angular position serving as the boundary as a reference And then tightening the yoke plug to an angular position that is at least less than the target angular position, and then loosening the yoke plug to the target angular position again. In the adjustment method of the steering device according to claim 1 or 2,
The angular position serving as the boundary is set along an approximate straight line that is set along the change tendency of the displacement of the rack shaft before sharply decreasing, and along the change tendency of the displacement of the rack shaft after sharply decreasing. The adjustment method of the steering apparatus detected as an angular position corresponding to the intersection with the approximated straight line. A steering device adjusting device that executes the steering device adjusting method according to any one of claims 1 to 3,
A motor,
A rotating socket that rotates integrally with the yoke plug in conjunction with the motor;
A rotation sensor for detecting the angular position of the yoke plug;
A displacement sensor for detecting a displacement in a direction intersecting the axis of the rack shaft with respect to the housing;
And a control device that controls the motor based on detection results of the rotation sensor and the displacement sensor. The adjusting device for a steering device according to claim 4,
The guide hole is provided biased on one side of the two ends of the housing,
The displacement sensor is an adjustment device for a steering device that detects a displacement of a measurement point set in a portion of the rack shaft that protrudes from the one end of the housing.