JP2013010390A - Rack guide mechanism and steering device - Google Patents

Abstract

Provided are a rack guide mechanism and a steering device that can reduce a feeling of catching at the start of steering operation and can further suppress rattling in a housing portion of a support yoke.
A meniscus having a guide surface 54a for supporting a peripheral portion in the rack axial direction X of an O-ring 41 in a notch recess 43 opened by a mounting groove 42 for mounting an O-ring 41 to a support yoke 31. A pair of spacer members 53 each having a guide part 54 having a shape and an extending part 55 extending from the guide part 54 are disposed. The pair of spacer members 53 are assembled in a state in which the end surfaces of the extending portions 55 inserted into the communication holes 51 between the pair of connecting portions 48 constituting the support yoke 31 are in contact with each other. A coil spring 56 is interposed between the guide portion 54 and the connecting portion 48 in a compressed state. Further, the peripheral portion of the O-ring 41 in the pinion axial direction Y is supported by a guide surface 48 a outside the pinion axial direction Y of the pair of connecting portions 48.
[Selection] Figure 5

Description

  The present invention relates to a rack and pinion type steering apparatus, a rack guide mechanism that presses a rack against the pinion, and a steering apparatus including the rack guide mechanism.

  2. Description of the Related Art Conventionally, a vehicle steering apparatus includes a rack and pinion type that converts a rotation of a pinion shaft accompanying a steering operation into a reciprocating movement of the rack shaft by engaging a pinion shaft and a rack shaft. Usually, such a rack and pinion type steering apparatus is provided with a rack guide mechanism that supports a rack shaft against a pinion shaft by a support yoke (rack guide) so that the rack shaft can reciprocate in the axial direction.

  By the way, since the rack shaft is in sliding contact with the support yoke, when the steering operation starts (when the rack shaft starts moving), the driver applies a frictional force (static frictional force) acting between the rack shaft and the support yoke. There is a possibility that steering must be performed with a steering force that exceeds, and this may lead to a so-called catching feeling that may lead to a reduction in steering feeling. Therefore, it is conceivable that a certain gap is formed between the support yoke and the accommodating portion, and the support yoke and the rack shaft are integrally moved in the axial direction to reduce the above-mentioned feeling of catching.

  However, in this case, since there is a gap around the entire circumference of the support yoke, it is also possible to move in the pinion axis direction (that is, the rack width direction) substantially orthogonal to the rack axis direction (rack axis direction). . For this reason, for example, when an external force such as a road surface reaction force acts on the rack shaft when traveling on a rough road, the rack shaft swings (rolls) in the vertical direction (pinion axis direction) of the vehicle, which causes the pinion axis direction. There is a possibility that the support yoke that has moved to the position hits the inner wall surface of the housing portion to generate a collision sound.

  In view of this, it has been proposed that the support yoke is configured to move more easily in the rack axis direction than in the pinion axis direction in the housing portion, thereby reducing the feeling of catching that occurs at the start of steering operation and suppressing the swing of the rack shaft. ing. For example, in the rack guide mechanism described in Patent Document 1, the bottom surface of the circumferential groove formed for mounting the O-ring on the outer peripheral surface of the support yoke (rack guide) is formed in an elliptical cross section, thereby The protruding amount of the O-ring from the outer peripheral surface is made larger in the pinion axis direction than in the rack axis direction. In a state where the support yoke is housed in the housing portion, the peripheral portion in the rack axial direction of the O-ring is separated from the inner wall surface of the housing portion, and the peripheral portion in the pinion axial direction of the O-ring contacts the inner wall surface of the housing portion. For this reason, the support yoke is accommodated due to the swing of the rack shaft in the vertical direction of the vehicle while suppressing the feeling of being caught at the start of the steering operation due to the relatively large gap in the rack axis direction between the support yoke and the accommodating portion. It is possible to avoid a large inclination in the pinion axis direction (rack width direction) as it hits the inner wall surface of the part.

  Patent Document 2 discloses a synthetic resin rack support having an arc concave surface that slides and guides a rack shaft (rack bar), and a pressing member that receives a biasing force of a coil spring and applies a pressing force toward the rack shaft. A rack in which an annular elastic member is disposed between the elastic member and a cylindrical bush member made of synthetic resin having one slit groove on the outer peripheral surface of the annular elastic member. A guide is disclosed.

Japanese Patent Laying-Open No. 2005-335667 (for example, FIG. 3) JP 2008-62858 A

  By the way, in the support yoke described in Patent Document 1, the outer peripheral surface of the O-ring abuts against the inner wall surface of the housing portion in the pinion axial direction, and is separated from the inner wall surface of the housing portion in the rack axial direction. is there. Although this gap suppresses the feeling of being caught at the start of the steering operation, the support yoke collides with the inner wall surface of the housing portion at the start of the steering operation.

  For example, when the support yoke is tilted while being displaced in the rack axis direction at the start of steering operation, it hits the inner wall surface of the housing portion, and at that time, the outer peripheral surface portion opposite to the displacement direction is separated from the inner wall surface of the housing portion and is relatively large. There is a gap. Thereafter, when the steering operation is turned back, the support yoke is tilted while being displaced to the opposite side, and hits the inner wall surface of the housing portion from a position having a relatively large gap. This causes a collision sound. For this reason, it is desired not to positively provide a gap between the support yoke and the housing portion, but to reduce the feeling of being caught at the start of the steering operation while keeping the gap as small or eliminated as possible.

  In Patent Document 2, since the rack guide is provided with a tightening margin between the outer peripheral surface of the cylindrical bush and the inner peripheral surface of the holding hole of the housing, the rack guide can be surely moved in the radial direction. Therefore, it is possible to prevent a collision sound from being generated. However, the elastic member made of rubber has a relatively large spring constant, and in order to displace the rack guide in the rack axis direction, it is necessary to compress the elastic member with a relatively large force, which becomes a feeling of being caught at the start of the steering operation. . Further, since the amount that the rack guide can be displaced in the rack axis direction is limited to the range of the tightening margin, a feeling of catching occurs when the tightening margin is exceeded.

  The present invention has been made to solve the above-described problems, and the object thereof is to reduce the feeling of being caught at the start of steering operation and to further suppress the rattling in the housing portion of the support yoke. An object of the present invention is to provide a rack guide mechanism and a steering device that can be used.

  In order to solve the above-mentioned problem, the invention according to claim 1 is provided in a steering device in which at least a meshing position between a pinion shaft rotating by a steering operation and a rack shaft meshed with the pinion shaft is accommodated in a housing. A rack guide mechanism that supports the rack shaft against the pinion shaft so as to reciprocate in the axial direction of the rack shaft, and is capable of moving in a contacting / separating direction that contacts and separates from the rack shaft. A support yoke housed in a housing portion formed in the housing, a biasing means for biasing the support yoke in a direction to press the support yoke against the rack shaft, and a circumferential mounting on a side peripheral surface of the support yoke An annular first elastic member and an axial direction of the rack shaft with respect to the support yoke in a state of supporting the inner peripheral surface of the first elastic member The spacer member is assembled so as to be movable relative to the support yoke, and the spacer member relatively moved in the axial direction of the rack shaft is urged in a direction to return to the original position and more than the first elastic member. The gist is that the second elastic member having a small spring constant is provided.

  According to the above configuration, at the start of the steering operation, the support yoke tends to move in the rack axis direction as the rack shaft moves in the axial direction (rack axis direction). The support yoke moves relative to the spacer member that supports the first elastic member while elastically deforming the second elastic member. Since the second elastic member has a smaller spring constant than the first elastic member, the support yoke can move in the rack axial direction with a relatively small force. When the force that the support yoke receives from the rack shaft during the movement of the support yoke exceeds the static friction force between them, the rack shaft starts to slide relative to the support yoke. Therefore, the feeling of being caught at the start of the steering operation is reduced.

  Further, when the steering operation is started, the force when the support yoke is relatively moved is transmitted to the spacer member via the second elastic member, so that the spacer member is displaced and the first elastic member hits the inner wall surface of the housing portion and is elastic. Compress. At this time, the support yoke is displaced with respect to the spacer member in the direction of movement of the rack shaft, but the spacer member is not so displaced, so the first elastic member supported by the spacer member is not so displaced. For this reason, in the location on the opposite side to the location which contacted the inner wall surface of the accommodating portion in the first elastic member, a very large gap does not occur between the inner wall surface of the accommodating portion. For this reason, the movement direction of the rack shaft is switched by the next turn of the steering operation, and even if the movement direction of the support yoke is switched accordingly, the clearance is not so much. Compared to the case of hitting the inner wall surface, the collision sound can be suppressed to a low level.

  In addition, if the rack shaft swings when the vehicle is traveling on a rough road, a force in the axial direction of the pinion shaft (rack shaft width direction) is applied from the rack shaft to the support yoke, but the support yoke moves relative to the spacer member. Because it is a direction that can not be, it can hardly move relative to the pinion axis direction. For this reason, the displacement of the support yoke in the pinion axis direction can be kept small. As a result, even if the support yoke receives a force in the pinion axial direction, it is easy to avoid hitting the inner wall surface of the housing portion, and a collision sound is hardly generated.

  According to a second aspect of the present invention, in the rack guide mechanism according to the first aspect, a plurality of the spacer members are arranged in the axial direction of the rack shaft, and the opposing end surfaces are in contact with each other. The gist of the invention is that the support yoke is assembled so as to be relatively movable in the axial direction of the rack shaft.

  According to the above configuration, the spacer member is composed of a plurality of parts arranged side by side in the axial direction of the rack shaft, and can be relatively moved integrally with respect to the support yoke by abutting the opposing end surfaces. . Since the spacer member is composed of a plurality of parts as described above, the spacer member can be assembled to the support yoke even if the support yoke is not composed of a plurality of parts.

  According to a third aspect of the present invention, in the rack guide mechanism according to the first aspect, one spacer member is provided for each first elastic member, and the support yoke is divided in the contact / separation direction. The gist is that the plurality of members are fixed in a state in which the spacer member and the second elastic member are assembled between the plurality of members.

  According to the said structure, a support yoke is comprised by the some member divided | segmented into the contact / separation direction (axial direction), and a spacer member and a 2nd elastic member are assembled | attached between each member. For this reason, even if the spacer member is constituted by one part, it can be assembled to the support yoke.

  According to a fourth aspect of the present invention, in the rack guide mechanism according to any one of the first to third aspects, the support yoke includes a concave portion in which the spacer member is accommodated, and the concave portion is in the contact / separation direction. A connecting portion that connects the divided portions at a substantially central position in the axial direction of the rack shaft, and the second elastic member is on both sides in the axial direction of the rack shaft with respect to the connecting portion. Further, the gist of the present invention is that it is interposed between the spacer member housed in the recess and the connecting portion.

  According to the above configuration, the second elastic member is disposed on both sides in the axial direction of the rack shaft with respect to the connecting portion located in the back of the concave portion of the support yoke, and is accommodated in the concave portion of the support yoke and is connected to the spacer member and the connecting portion. It is intervened between. For this reason, the spacer member moved relative to the support yoke can be returned to the original position.

  According to a fifth aspect of the present invention, in the rack guide mechanism according to any one of the first to fourth aspects, the spacer member includes a pair of guide portions that support a part of the first elastic member; An extension portion that extends from each guide portion and is connected to or abuts the guide portion, and is assembled so as to be movable relative to the support yoke in the extension direction of the extension portion. And

  According to the above configuration, the inner peripheral surface of the first elastic member can be supported by the pair of guide portions, and at least the extending portions extending from the respective guide portions are connected or abutted with each other. The portion can move relative to the support yoke integrally in the rack axis direction.

  According to a sixth aspect of the present invention, in the rack guide mechanism according to any one of the first to fourth aspects, the spacer member has an annular portion that supports an inner peripheral surface of the first elastic member. The gist.

  According to the said structure, the inner peripheral surface of a 1st elastic member can be supported over the circumferential direction whole region by the annular part of a spacer member. For example, when the first elastic member hits the inner wall surface of the accommodating portion, it is possible to more reliably avoid the situation where the unsupported portion of the first elastic member is displaced inward too much and the support yoke hits the inner wall surface of the accommodating portion. .

  According to a seventh aspect of the present invention, a pinion shaft that is rotated by a steering operation, a rack shaft meshed with the pinion shaft, and a reciprocating motion in the axial direction of the rack shaft while pressing the rack shaft against the pinion shaft A rack guide mechanism according to any one of claims 1 to 6, and a pinion shaft, a rack that accommodates the rack shaft, and the rack guide mechanism, and the rack guide mechanism is formed in the housing. The present invention is characterized in that a support yoke that is accommodated in a state of being movable in a contact / separation direction that contacts / separates with respect to the rack shaft is provided in a state of being pressed against the rack shaft by the biasing means. .

  According to the above configuration, the steering device includes the rack guide mechanism described in claims 1 to 6, so that the same operational effects as the invention relating to the rack guide mechanism can be obtained.

  According to the present invention, it is possible to provide a rack guide mechanism and a steering device that can reduce the feeling of catching at the start of steering operation and can further suppress rattling in the housing portion of the support yoke.

The schematic block diagram which shows the electric power steering apparatus in 1st Embodiment. Sectional drawing which shows a rack and pinion mechanism and peripheral structure. The perspective view which shows the support yoke with a behavior stabilization mechanism. AA line sectional view in FIG. (A) Before steering start, (b) BB sectional drawing in FIG. 3 which shows the time of steering start. The disassembled perspective view which shows the support yoke with a behavior stabilization mechanism. The disassembled perspective view which shows the support yoke with the behavior stabilization mechanism in 2nd Embodiment. Sectional drawing which similarly shows a support yoke. The plane sectional view showing the support yoke with a behavior stabilization mechanism in a 3rd embodiment.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, in an electric power steering apparatus (EPS) (hereinafter simply referred to as “steering apparatus 1”), a steering shaft 3 to which a steering wheel 2 is fixed is connected to a rack shaft 5 via a rack and pinion mechanism 4. It is connected with. Thereby, the rotation of the steering shaft 3 accompanying the steering operation is converted into a reciprocating linear motion of the rack shaft 5 by the rack and pinion mechanism 4. The steering shaft 3 is formed by connecting a column shaft 8, an intermediate shaft 9, and a pinion shaft 10. 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 steering device 1 according to the present embodiment is configured as a so-called column assist type EPS that rotationally drives the column shaft 8 using the motor 13 as a drive source. Specifically, the motor 13 is drivingly connected to the column shaft 8 via a speed reduction mechanism 14 composed of a worm and wheel. The rotation of the motor 13 is decelerated by the speed reduction mechanism 14 and transmitted to the column shaft 8 so that the motor torque is applied to the steering system as an assist force.

Next, the rack and pinion mechanism and its peripheral configuration will be described.
The rack and pinion mechanism 4 is configured by meshing rack teeth 17 formed on the rack shaft 5 with pinion teeth 18 formed on the pinion shaft 10. The rack teeth 17 of the present embodiment are formed as inclined teeth (helical gears) whose teeth are inclined with respect to the axis of the rack shaft 5, and the pinions 18 are aligned with the axis of the pinion shaft 10. It is formed in the inclined tooth inclined with respect to it. The rack shaft 5 is arranged in a substantially cylindrical rack housing 19 with a predetermined crossing angle with the pinion shaft 10. The steering device 1 is also provided with a rack guide mechanism 20 that supports the rack shaft 5 so as to reciprocate in the axial direction of the rack shaft 5 (hereinafter also referred to as “rack shaft direction”) while pressing the rack shaft 5 against the pinion shaft 10. It has been. And the backlash between the rack teeth 17 and the pinion teeth 18 is properly maintained by the rack guide mechanism 20, and the occurrence of rattling noise is suppressed.

  Specifically, as shown in FIG. 2, the rack guide mechanism 20 is accommodated in the rack housing 19 with the rack shaft 5 sandwiched between the pinion accommodating portion 21 in which the pinion shaft 10 is accommodated and the pinion accommodating portion 21. The rack guide accommodating portion 22 is formed. The pinion accommodating portion 21 extends in the axial direction of the pinion shaft 10 (hereinafter also referred to as “pinion axial direction”), and is formed in a cylindrical shape having an open upper end in FIG. On the other hand, the rack guide accommodating portion 22 extends in a direction substantially orthogonal to the rack shaft 5 and the pinion shaft 10, and one end (the right end in FIG. 2) opens into the rack housing 19 and the other end (the left end in FIG. 2). It is formed in a cylindrical shape opened to the outside of the rack housing 19.

  The pinion shaft 10 is accommodated in the pinion accommodating portion 21 in such a manner that an upper end 10 a connected to the intermediate shaft 9 (see FIG. 1) protrudes from the pinion accommodating portion 21. The pinion shaft 10 is rotatably supported by bearings 23 and 24 provided in the pinion housing portion 21. The pinion teeth 18 are formed between two portions of the pinion shaft 10 that are supported by the bearings 23 and 24.

  As shown in FIG. 2, the rack guide mechanism 20 includes a support yoke 31 that supports the rack shaft 5 so as to be capable of reciprocating in the axial direction, and a coil spring 32 that serves as an urging means that presses the support yoke 31 against the rack shaft 5. I have. The support yoke 31 is formed in a substantially cylindrical shape, and in the rack guide housing portion 22, the contact yoke 31 is in contact with and away from the rack shaft 5 in a direction substantially perpendicular to the axial directions of the rack shaft 5 and the pinion shaft 10. It is accommodated so as to be movable in the separation direction.

  2 and 3, the end of the support yoke 31 on the rack shaft 5 side is recessed in an arc shape corresponding to the back surface 5a on the opposite side of the rack shaft 5 from the rack teeth 17 side. A groove portion 33 is formed. The rear surface 5a of the rack shaft 5 is slidably in contact with the groove 33. The support yoke 31 of this embodiment is formed of a metal material, and the inner peripheral surface of the groove 33 is coated with a synthetic resin made of a low friction material, for example, on a metal plate for the purpose of reducing sliding friction with the rack shaft 5. An arcuate sheet member (not shown) is fixed. A recess 35 is formed at the end of the support yoke 31 opposite to the rack shaft 5 side.

  The external opening end 36 opened to the outside of the rack housing 19 in the rack guide accommodating portion 22 is closed by screwing a substantially disc-shaped cap 37. The coil spring 32 is disposed between the support yoke 31 and the cap 37 in a compressed state, and presses the support yoke 31 against the rack shaft 5. Specifically, one end of the coil spring 32 is seated on the bottom surface of the recess 35 of the support yoke 31, and the other end is seated on the inner surface 37 a of the cap 37. Thereby, the support yoke 31 is configured to support the rack shaft 5 so as to be capable of reciprocating in the rack axis direction X while pressing the rack shaft 5 toward the pinion shaft 10 side.

  As shown in FIGS. 2 and 3, O-rings 41 as first elastic members are packaged on the outer peripheral surface 31 a of the support yoke 31 at two locations in the axial direction (contact / separation direction). Specifically, the two O-rings 41 are positioned in the axial direction of the support yoke 31 in the two annular mounting grooves 42 recessed along the circumferential direction on the outer peripheral surface 31 a of the support yoke 31. And it has mounted | worn in the state which the one part protruded from the outer peripheral surface 31a in the whole area of the circumferential direction. As shown in FIG. 2, the two O-rings 41 are in contact with each other over substantially the entire circumference of the inner peripheral surface 22 a of the rack guide housing portion 22, and the rack shaft of the support yoke 31 in the rack guide housing portion 22. Shaking in the direction X and the pinion axis direction Y (rack width direction) is suppressed. In other words, there is no gap between the O-ring 41 attached to the support yoke 31 and the inner peripheral surface 22a of the rack guide accommodating portion 22, or the gap is extremely narrow even if there is a gap.

  While the O-ring 41 and the inner peripheral surface 22a of the rack guide housing portion 22 are substantially in contact with the support yoke 31 of this embodiment, the support yoke 31 is easily displaced in the rack axial direction X, A behavior stabilization mechanism 40 that suppresses displacement in the pinion axial direction Y is provided.

(Behavior stabilization mechanism)
Next, the behavior stabilization mechanism 40 provided in the support yoke 31 will be described. The behavior stabilization mechanism 40 reduces the resistance (static frictional force) that the rack shaft 5 receives from the support yoke 31 when the rack shaft 5 starts moving in the axial direction X with the start of the steering operation. It has a function to reduce the feeling of catching. Further, the behavior stabilization mechanism 40 suppresses the displacement of the support yoke 31 in the pinion axis direction Y when the rack shaft 5 swings in the vehicle vertical direction, so that the support yoke 31 hits the inner peripheral surface 22a of the rack guide housing portion 22. It has a function to suppress the generation of the hitting sound caused by. This behavior stabilization mechanism 40 includes an O-ring 41 attached to the support yoke 31 as one of its constituent parts, and the elastic characteristics of the O-ring 41 are anisotropic in the rack axis direction X and the pinion axis direction Y. Give.

  Hereinafter, a specific configuration of the behavior stabilization mechanism 40 will be described with reference to FIGS. 4 shows a cross section taken along the line AA in FIG. 3, and FIG. 5 shows a cross section taken along the line BB. FIG. 6 is an exploded perspective view of the support yoke 31 with the behavior stabilization mechanism 40.

  As shown in FIGS. 4 to 6, one behavior stabilization mechanism 40 is provided for each O-ring 41. The support yoke 31 is opened by a mounting groove 42 on the outer peripheral surface 31a and is recessed inward in the radial direction with a constant width (width in the axial direction) substantially the same as the opening width, as viewed in plan view in FIG. A notch recess 43 as a recess having a predetermined shape shown in FIG. 5A, the cut-out recess 43 has a pair of substantially square shapes facing each other with a certain gap in the pinion axial direction Y from a circular region inside the outer peripheral surface 31a of the support yoke 31. It is equal to the shape of the area excluding the connecting portion 48.

  As shown in FIG. 6, the support yoke 31 includes three portions divided in the axial direction (separation direction) by two notch recesses 43, that is, a distal end portion 45, an intermediate portion 46, and a proximal end portion 47. The three portions 45 to 47 are integrally formed in a state where those adjacent in the axial direction are connected via a pair of connecting portions 48.

  As shown in FIG. 5A, the outer peripheral surface facing the pinion axial direction Y outside of the connecting portion 48 is an arcuate guide surface 48 a that guides the inner peripheral surface of the O-ring 41. The guide surface 48a is formed in an arc surface having the same diameter as the inner diameter of the O-ring 41, the width in the rack axis direction X is about 1/3 of the diameter of the support yoke 31, and the height is the width of the notch recess 43. It has a substantially quadrangular prism shape equal to. Further, both side surfaces of the connecting portion 48 outside the rack axis direction X are flat surfaces 48 b perpendicular to the rack axis direction X. A communication hole 51 extending along the rack axis direction X with a constant width in the pinion axis direction Y is formed between the pair of connection portions 48.

  A pair of spacer members 53 are housed on both sides of the connecting portion 48 in the rack axial direction X in the notch recess 43. The spacer member 53 includes a meniscus guide portion 54 having a semicircular arc guide surface 54a that supports a part of the inner peripheral surface of the O-ring 41, and a portion of the guide portion 54 that is opposite to the guide surface 54a. And a rectangular plate-like extending portion 55 extending from the center in the width direction. The guide surface 54a is formed as an arc surface having substantially the same diameter as the inner peripheral diameter of the O-ring 41 so that the inner peripheral surface of the O-ring 41 can be guided. The pair of spacer members 53 are assembled in a state where the extended portions 55 are inserted into the communication holes 51. In the state of FIG. 5A, the extending portions 55 of the pair of spacer members 53 extend toward the center of the support yoke 31. That is, each extending portion 55 extends on the same axis from each guide portion 54. In addition, the surfaces of the extending portion 55 located on both sides of the pinion axis direction Y in the portion opposite to the guide surface 54a of the guide portion 54 are flat surfaces 54b parallel to the pinion axis direction Y. 54b opposes each flat surface 48b of the connecting portion 48 with a gap.

  As shown in FIG. 5A, a coil spring 56 as a second elastic member is interposed between the flat surface 48b of the connecting portion 48 and the flat surface 54b of the guide portion 54 in a compressed state. . As shown in FIG. 6, spring seats 57 and 58 are recessed in the flat surfaces 48 b and 54 b at positions facing each other. The coil spring 56 is interposed between the flat surfaces 48b and 54b in a state where both ends thereof are in contact with the spring seats 57 and 58. The spacer member 53 is biased in the direction toward the outside of the support yoke 31 in the rack axial direction X by the biasing force of the coil spring 56. In a state where the spacer member 53 is assembled, the O-ring 41 is mounted while being guided from the inside to the guide surface 54 a of the guide portion 54 and the guide surface 48 a of the connecting portion 48. In the mounted state of the O-ring 41, the pair of spacer members 53 are in a state in which the extending portions 55 abut on the end surfaces. For this reason, the distance between the guide surfaces 54 a in the pair of spacer members 53 is kept constant substantially equal to the inner diameter of the O-ring 41. The O-ring 41 is supported by the guide surface 48a of the connecting portion 48 at the peripheral portion in the pinion axial direction Y, so that the O-ring 41 cannot be moved relative to the support yoke 31 in the pinion axial direction Y. Is supported by the spacer member 53, the relative movement in the rack axial direction X is possible with the spacer member 53 with respect to the support yoke 31.

  Here, the O-ring 41 is compressed and deformed in the thickness direction when it hits the inner peripheral surface 22 a of the rack guide housing portion 22. The spring constant in the thickness direction of the O-ring 41 is such that even if the support yoke 31 is displaced in the pinion axis direction Y and the O-ring 41 hits the inner peripheral surface 22a and compressively deforms in the thickness direction, The value is not set to 22a. That is, the O-ring 41 is set to be relatively hard. On the other hand, the spring constant of the coil spring 56 is sufficiently smaller than the spring constant of the O-ring 41 in the thickness direction. The spacer member 53 is urged by two coil springs 56 in the rack axial direction X. The spring constant of the two coil springs 56 is smaller than the spring constant in the thickness direction of the O-ring 41. Is set. Further, the amount of deformation by which the two coil springs 56 can be elastically deformed is set sufficiently longer than the amount of deformation by which the O-ring 41 can be elastically compressed in the thickness direction. In this embodiment, when the steering operation starts, the amount (distance) by which the spacer member 53 can move relative to the connecting portion 48 of the support yoke 31 in the rack axis direction X is elastically compressed by the O-ring 41 hitting the inner peripheral surface 22a. The O-ring 41 is set to a value less than the protruding amount from the outer peripheral surface 31a of the support yoke 31.

<Action>
Next, the operation of the steering apparatus 1 including the rack guide mechanism 20 configured as described above will be described.

  While the vehicle is running, when the steering operation is slightly performed for the purpose of maintaining straightness or with a gentle curve, the rack shaft 5 that meshes with the pinion shaft 10 that rotates by the steering operation moves in the rack axis direction X To do. At this time, a force in the rack axis direction X is applied from the rack shaft 5 to the support yoke 31 by the friction between the rack shaft 5 and the support yoke 31.

  Before the steering operation is started, the spacer member 53 constituting the behavior stabilizing mechanism 40 provided in the support yoke 31 is arranged in the rack axial direction X with respect to the connecting portion 48 of the support yoke 31 as shown in FIG. It is in an initial state in which neither is relatively moved. At the start of the steering operation, the support yoke 31 receives a force in the moving direction (right direction in FIG. 5) from the rack shaft 5 from this initial state. Then, as shown in FIG. 5B, the support yoke 31 slightly moves to the right side in the figure while the connecting portion 48 compresses the coil spring 56 arranged on the right side in the figure. At this time, the spacer member 53 receives a force in the right direction in FIG. 5 from the coil spring 56 elastically compressed by the movement of the connecting portion 48. As a result, the right peripheral portion in FIG. 5 of the O-ring 41 is pushed by the inner peripheral surface 22a and elastically compressed.

  Thus, at the start of the steering operation, the support yoke 31 can be slightly displaced in the moving direction of the rack shaft 5 by a relatively small force by elastic deformation of the coil spring 56 having a smaller spring constant than the O-ring 41. While the support yoke 31 moves slightly following the rack shaft 5, the force received by the support yoke 31 from the rack shaft 5 exceeds the static frictional force between the two, and at this time, the rack shaft 5 moves against the support yoke 31. And begin to slide. For this reason, the driver can perform the steering operation without much catching feeling at the start of the steering operation.

  As shown in FIG. 5B, when starting the steering operation, the coil spring 56 disposed on the side opposite to the moving direction of the support yoke 31 (left side in FIG. 5) with respect to the connecting portion 48 extends. A restoring force in the contraction direction acts on the extended coil spring 56, but since the end surfaces of the extending portions 55 of the pair of spacer members 53 are in contact with each other, the distance between the pair of guide surfaces 54a (the support yoke 31). The distance passing through the axis of the O-ring 41 is maintained at a constant value substantially equal to the inner diameter of the O-ring 41. As a result, the peripheral portion of the O-ring 41 opposite to the moving direction of the connecting portion 48 (the left side in FIG. 5) is slightly on the right side from the left inner peripheral surface 22a (the compressed portion of the right peripheral portion of the O-ring 41). However, even if there is a gap, it is extremely small.

  For example, when the driver turns back to return the steering operation to the original position (neutral position), the movement direction of the rack shaft 5 is reversed according to the turning operation, and the support yoke 31 follows the rack shaft 5. Suddenly reverses in the reverse direction (leftward in FIG. 5B). At this time, there is no gap or very little between the peripheral portion of the O ring 41 on the reverse side (left side in FIG. 5) and the inner peripheral surface 22a. For this reason, the support yoke 31 does not tilt greatly, and the support yoke 31 does not hit the inner peripheral surface 22a. In addition, the impact when the support yoke 31 re-contacts the inner peripheral surface 22a is also suppressed. As a result, the occurrence of a collision sound when turning back the steering operation is suppressed, and the re-contact sound is also reduced.

  Further, for example, when an external force (kickback force) such as a road surface reaction force acts on the rack shaft 5 when traveling on a rough road, the rack shaft 5 swings (rolls) in the vehicle vertical direction (pinion axis direction Y), The rack shaft 5 is displaced in the pinion axis direction Y. Then, a force in the pinion axial direction Y is applied from the rack shaft 5 to the support yoke 31 that holds the rack shaft 5. However, as shown in FIG. 5A, the peripheral portion of the O-ring 41 in the pinion axial direction Y is supported by the connecting portion 48 from the inside and is in contact with the inner peripheral surface 22a. For this reason, the inclination of the support yoke 31 in the pinion axis direction Y is suppressed to a small extent by the extent that the peripheral part of the O-ring 41 in the pinion axis direction Y is pushed by the inner peripheral surface 22a and is slightly elastically compressed. As a result, the outer peripheral surface 31a of the support yoke 31 is prevented from hitting the inner peripheral surface 22a on the side displaced in the pinion axial direction Y. For this reason, when traveling on rough roads, the generation of collision noise caused by the support yoke 31 displaced in the pinion axial direction Y hitting the inner peripheral surface 22a is suppressed.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The support yoke 31 that constitutes the rack guide mechanism 20 has a spacer member 53 that supports the O-ring 41 mounted in the mounting groove 42 on the outer peripheral surface 31 a from the inside, and is smaller than the spring constant of the O-ring 41. A behavior stabilizing mechanism 40 that biases the rack axis direction X outward via a coil spring 56 having a spring constant is provided. The behavior stabilizing mechanism 40 gives the O-ring 41 elastic anisotropy that is more easily elastically displaced in the rack axis direction X than in the pinion axis direction Y with respect to the support yoke 31. For this reason, it is not necessary to provide a gap between the peripheral portion of the O-ring 41 in the rack axis direction X and the inner peripheral surface 22a for suppressing a feeling of being caught when starting the steering operation.

  The support yoke 31 receiving the force in the rack axis direction X from the rack shaft 5 at the start of the steering operation is slightly displaced with a relatively small force while elastically deforming the pair of coil springs 56 having a relatively small spring constant. Can do. When the support yoke 31 is slightly displaced and the force received from the rack shaft 5 exceeds the static frictional force on the contact surface between them, the support yoke 31 starts to slide on the rack shaft 5. Thus, the apparent frictional resistance between the rack shaft 5 and the support yoke 31 can be reduced. For this reason, the steering operation can be performed without a feeling of being caught so much at the start of the steering operation.

  (2) Since the pair of spacer members 53 are in a state in which the end surfaces of the extending portions 55 are in contact with each other, the distance between the pair of guide surfaces 54 a is maintained at a constant value substantially equal to the inner diameter of the O-ring 41. . For this reason, when the steering operation is started, a relatively large gap is generated between the peripheral portion of the O-ring 41 opposite to the peripheral portion on the moving direction side of the support yoke 31 from the inner peripheral surface 22a. You can avoid that. As described above, when the steering operation is started, the clearance between the peripheral portion of the O-ring 41 opposite to the moving direction of the support yoke 31 and the inner peripheral surface 22a is eliminated or slightly suppressed, so that the steering operation is returned to the original position. In this case, it is possible to prevent the inverted support yoke 31 from hitting the inner peripheral surface 22a, and thus to suppress the occurrence of collision noise.

  (3) The O-ring 41 is in contact with the inner peripheral surface 22a or is in a state where there is a slight gap between the inner peripheral surface 22a. Under this state, the peripheral portion of the O-ring 41 in the pinion axial direction Y is The support surface 31 is supported by a guide surface 48 a of a connecting portion 48 formed on the support yoke 31. For this reason, the amount of displacement when the support yoke 31 receives a force in the pinion axial direction Y is suppressed to a value corresponding to the amount of elastic compression of the O-ring 41 in the thickness direction. As a result, the support yoke 31 displaced in the pinion axial direction Y is prevented from hitting the inner peripheral surface 22a.

  (4) The behavior stabilization mechanism 40 is configured to adjust the ease of elastic displacement in the rack axis direction X and the pinion axis direction Y by combining the O-ring 41 and the coil spring 56. For this reason, by selecting a spring constant of the coil spring 56 in the rack axial direction X while giving elasticity of an appropriate hardness using a relatively hard O-ring 41 in the pinion axial direction Y, Appropriately soft elasticity suitable for reducing the feeling of catching can be imparted. As described above, according to the behavior stabilization mechanism 40 of the present embodiment, by selecting the spring constants of the O-ring 41 and the coil spring 56, the ease of elastic deformation in the rack axis direction X and the pinion axis direction Y is improved. It can be controlled according to the required value.

  For example, in the configuration in which elastic anisotropy is imparted only to the O-ring as in Patent Document 1, there is a limit to the difference in the amount of displacement that varies depending on the direction. For example, if the elasticity in the rack axial direction X of the O-ring is softened to an appropriate value in order to suppress the feeling of catching, the elasticity becomes too soft for the pinion axial direction Y and swings in the vertical direction of the vehicle due to an external force when traveling on a rough road. When the support yoke receiving the force from the rack shaft moves in the pinion axis direction, it hits the inner wall surface of the housing portion, which causes a collision sound. On the other hand, the O-ring 41 attached to the support yoke 31 of this embodiment sets the elasticity in the pinion axial direction Y to be relatively hard while ensuring the elasticity in the rack axial direction X to be moderately soft by the coil spring 56. be able to. Therefore, it is possible to prevent both a collision sound when turning back the steering operation and a collision sound when the support yoke 31 is displaced in the pinion axial direction Y when traveling on a rough road while suppressing a feeling of catching at the start of the steering operation. Can do.

  (5) A pair of spacer members 53 are provided, and the extended portions 55 are inserted into the communication holes 51 between the connecting portions 48, and the end surfaces of the extended portions 55 are in contact with each other. To the support yoke. For this reason, the spacer member 53, the coil spring 56, and the O-ring 41 can be assembled in the notch recess 43 without dividing the support yoke 31 into a plurality of parts. For this reason, the support yoke 31 can be constituted by one part, and the support yoke 31 having the behavior stabilizing mechanism 40 can be constituted by a small number of parts.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS. The present embodiment is an example of a configuration in which the support yoke 31 is divided into a plurality of parts. As shown in FIGS. 7 and 8, the support yoke 31 is composed of three parts, that is, a distal end member 61, an intermediate member 62, and a proximal end member 63. Each component constituting the behavior stabilization mechanism 40 is assembled on each upper surface (surface on the rack shaft 5 side) of the intermediate member 62 and the base end member 63. On each upper surface of the intermediate member 62 and the base end member 63, a pair of square plate-like restricting portions 64 facing each other in the pinion axial direction Y protrudes. The restricting portion 64 has the same function as the connecting portion 48 in the first embodiment. In each upper surface of the intermediate member 62 and the base end member 63, the region other than the restricting portion 64 is a recess 65 that is recessed in a predetermined shape. The recess 65 is a space for accommodating the spacer member 66 and the coil spring 56. The spacer member 66 includes a pair of meniscus-shaped guide portions 67 and a connection portion 68 that integrally connects both the guide portions 67. That is, the spacer member 66 of this embodiment has a configuration in which a pair of spacer members 53 that are two parts in the first embodiment are integrally formed as one part. In the present embodiment, the connecting portion 68 corresponds to an extending portion that extends from each guide portion on the same axis.

  In order to connect the members 61 to 63 and assemble the support yoke 31 integrally, two bolts 70 are fastened to the members 61 to 63. Therefore, bolt insertion holes 61a, 62a, and 63a are formed in the members 61 to 63, respectively. After assembling the parts constituting the behavior stabilization mechanism 40 to the members 62 and 63, the members 61 to 63 are arranged in a row, and the bolt 70 is inserted into the bolt insertion holes 61a to 63a and fastened to be tightened. 61-63 are assembled integrally.

According to the second embodiment, the effects (1) to (4) in the first embodiment can be obtained in the same manner, and the following effects can be obtained.
(6) The assembly of the behavior stabilization mechanism 40 to the support yoke 31 can be easily performed as compared with the configuration of the first embodiment.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG. This embodiment is an example in which the shape of the spacer member is different. A behavior stabilization mechanism 80 having the structure shown in FIG. 9 is employed. The components of the behavior stabilization mechanism 80 shown in FIG. 9 are assembled on the upper surfaces (the surfaces on the rack shaft 5 side) of the members 62 and 63 other than the tip member among the plurality of components constituting the support yoke 31. A square plate-shaped restricting portion 81 having the pinion axis direction Y in the longitudinal direction in a plan view protrudes from the center of the upper surface of the members 62 and 63. A region other than the restricting portion 81 on each upper surface of each member 62, 63 is a recess 85 that is recessed in a predetermined shape. The recess 85 is a space for accommodating the spacer member 82 and the coil spring 56.

  The spacer member 82 has an annular portion 83 whose outer peripheral shape is circular, and a sufficiently wide rectangular hole 84 into which the restricting portion 81 can be inserted is formed at the center thereof. The hole 84 is formed such that the width in the pinion axial direction Y is slightly wider than the width in the pinion axial direction Y of the restricting portion 81, and the width in the rack axial direction X is sufficiently wider than the width in the rack axial direction X of the restricting portion 81. . The spacer member 82 is assembled on the upper surfaces of the members 62 and 63 so as to be relatively movable in the rack axis direction X with respect to the restricting portion 81 disposed in the hole 84.

  Two coil springs 56 are interposed between the spacer member 82 and the restricting portion 81 in a compressed state on both sides of the restricting portion 81 in the rack axis direction X in the hole 84 of the spacer member 82. . The outer peripheral surface 82 a of the spacer member 82 has an outer diameter that is substantially equal to the inner diameter of the O-ring 41, and supports the inner peripheral surface of the O-ring 41 that is mounted in the mounting groove 42. Therefore, the outer peripheral surface 82a of the spacer member 82 is compressed between the coil spring 56 between the regulating surfaces 81a on both sides of the regulating portion 81 in the rack axis direction X and the flat surfaces 82b of the spacer member 82 facing the rack axis direction X. It is inserted in the state. As in the first embodiment, a configuration in which the spacer member 82 is divided into two parts divided in the rack axis direction X and assembled to the support yoke 31 in a state in which the opposing end surfaces are in contact with each other can be employed. According to these configurations, the same effects (1) to (4) and (6) as those in the above embodiments can be obtained, and the entire inner peripheral surface of the O-ring 41 is covered by the outer peripheral surface 82a of the spacer member 82. Can guide.

The embodiment described above may be modified as follows.
In consideration of reducing sliding friction, the spacer member may be made of a highly self-lubricating polymer (for example, polyacetal (POM)) or a surface-treated metal for reducing friction. . An example of this type of surface treatment is a synthetic resin coating made of a low friction material.

  -The structure which has arrange | positioned the coil spring 56 as a 2nd elastic member one each on the both sides of the rack axial direction X with respect to the connection part 48 or the control parts 64 and 81 may be sufficient. Of course, three or more second elastic members may be arranged.

The number of O-rings 41 attached to the support yoke 31 can be changed as appropriate, and may be one or three or more, for example.
-The extension part of a spacer member is good also as two. In this case, one coil spring as the second elastic member may be arranged between the two extending portions.

-A 1st elastic member is not limited to an O-ring. An annular rubber belt (rubber ring) may be used.
The second elastic member is not limited to a coil spring, but may be a leaf spring, a bamboo shoot spring, a disc spring, or an elastic polymer.

-In the said embodiment, you may apply to the steering device which has only a telescopic adjustment function or only a tilt adjustment function.
In the embodiment, the steering device 1 is configured as a so-called column assist type electric power steering device (EPS) that applies an assist force to the column shaft 8 that constitutes the column shaft. However, the present invention is not limited to this, and the present invention may be applied to an EPS other than column assist, a hydraulic power steering device, or a non-assist type steering device such as a so-called rack assist type.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering device (EPS) as a steering device, 2 ... Steering wheel, 3 ... Steering shaft, 4 ... Rack and pinion mechanism, 5 ... Rack shaft, 10 ... Pinion shaft, 17 ... Rack tooth, 18 ... Pinion tooth , 19... Rack housing as a housing, 20... Rack guide mechanism, 22... Rack guide accommodating portion, 22 a... Inner peripheral surface as an inner wall surface, 31 ... Support yoke, 32 ... Coil spring as urging means, 40. Stabilization mechanism, 41 ... O-ring as first elastic member, 42 ... mounting groove, 43 ... notched recess as recess, 45 ... tip portion, 46 ... intermediate portion, 47 ... base end portion, 48 ... coupling portion, 48a ... Guide surface, 48b ... Flat surface, 51 ... Communication hole, 53 ... Spacer member, 54 ... Guide part, 55 ... Extension part, 56 ... Second elastic member All coil springs, 61: distal end member, 62: intermediate member, 63: proximal end member, 61a to 63a ... bolt insertion hole, 64 ... regulating portion, 65 ... recessed portion, 66 ... spacer member, 67 ... guide portion, 68 ... Connection part as extension part, 70 ... bolt, 80 ... behavior stabilization mechanism, 81 ... regulation part, 81a ... regulation surface, 82 ... spacer member having annular part, 82a ... outer peripheral surface, 82b ... flat surface, 83 ... Annular part, 84... Hole, X... Axial direction of rack axis (rack axis direction), Y... Axial direction of pinion axis (pinion axis direction) (rack width direction).

Claims (7)

At least a meshing position between a pinion shaft rotated by a steering operation and a rack shaft meshed with the pinion shaft is provided in a steering device housed in a housing, and the rack shaft is pressed against the pinion shaft while the rack shaft is pressed against the pinion shaft. A rack guide mechanism that supports reciprocation in an axial direction,
A support yoke accommodated in an accommodating portion formed in the housing in a state of being movable in an approaching / separating direction in contact with / separating from the rack shaft;
An urging means for urging the support yoke in a direction of pressing the support yoke against the rack shaft;
An annular first elastic member mounted along a circumferential direction on a side peripheral surface of the support yoke;
A spacer member assembled so as to be relatively movable in the axial direction of the rack shaft with respect to the support yoke in a state of supporting the inner peripheral surface of the first elastic member;
A second elastic member that biases the spacer member moved relative to the support yoke in the axial direction of the rack shaft in a direction to return to the original position and has a smaller spring constant than the first elastic member. A rack guide mechanism characterized by that. The rack guide mechanism according to claim 1,
The spacer member is assembled so as to be relatively movable in the axial direction of the rack shaft with respect to the support yoke in a state where a plurality of the spacer members are arranged in the axial direction of the rack shaft and the respective opposing end surfaces are in contact with each other. A rack guide mechanism characterized by that. The rack guide mechanism according to claim 1,
One spacer member is provided for each of the first elastic members,
The support yoke is composed of a plurality of members divided in the contact / separation direction,
The rack guide mechanism, wherein the plurality of members are fixed in a state where the spacer member and the second elastic member are assembled between the plurality of members. The rack guide mechanism according to any one of claims 1 to 3,
The support yoke is formed with a recess that accommodates the spacer member, and a connecting portion that connects a portion of the recess divided in the contact / separation direction at a substantially central position in the axial direction of the rack shaft. And
The rack is characterized in that the second elastic member is interposed between the spacer member accommodated in the recess and the connecting portion on both axial sides of the rack shaft with respect to the connecting portion. Guide mechanism. The rack guide mechanism according to any one of claims 1 to 4,
The spacer member includes a pair of guide portions that support a part of the first elastic member, and an extension portion that extends from each guide portion and is connected to or in contact with the support yoke. The rack guide mechanism is assembled so as to be relatively movable in the extending direction of the extending portion. The rack guide mechanism according to any one of claims 1 to 4,
The rack guide mechanism, wherein the spacer member has an annular portion that supports an inner peripheral surface of the first elastic member. A pinion shaft that rotates by steering operation;
A rack shaft meshed with the pinion shaft;
The rack guide mechanism according to any one of claims 1 to 6, wherein the rack guide mechanism is supported so as to reciprocate in the axial direction of the rack shaft while pressing the rack shaft against the pinion shaft.
A housing that houses the pinion shaft, the rack shaft, and the rack guide mechanism;
The rack guide mechanism presses a support yoke housed in a housing part formed in the housing so as to be movable toward and away from the rack shaft against the rack shaft by the biasing means. A steering device characterized by being provided in a state.

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