JP2012166749A - Steering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering system capable of stabilizing behavior of a rack shaft.SOLUTION: An EPS (electric power steering system) is provided with a rack guide mechanism 24 having: a support yoke 41 housed in a rack guide housing 32 so as to be moved to be contacted to a rack shaft and to be moved away from the rack shaft 5; and a coil spring 42 pressing the support yoke 41 to the rack shaft 5. Pinion teeth 22 of a pinion shaft 10 and rack teeth 21 of the rack shaft 5 are formed into forms of helical gears, respectively. The rack guide mechanism 24 has: paired support pieces 57 which come in slide contact with both lateral sides of a meshing part 56 of the rack shaft 5 that meshes with the pinion shaft 10; and a guide bush 51 fixed inside the rack guide housing 32.

Description

  The present invention relates to a rack and pinion type steering apparatus.

  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. Normally, this type of steering apparatus is provided with a rack guide mechanism that supports the rack shaft so as to reciprocate in the axial direction while pressing the rack shaft against the pinion shaft (see, for example, Patent Document 1).

  In the example shown in FIG. 10, the rack guide mechanism 91 includes a support yoke 93 that supports the rack shaft 92 so as to reciprocate in the axial direction, and a coil spring 94 that presses the support yoke 93 against the rack shaft 92. 95 is accommodated in a cylindrical rack guide accommodating portion 96 formed in 95. The support yoke 93 is formed in a columnar shape, and is housed in the rack guide housing portion 96 so as to be movable in a contact / separation direction that contacts / separates the rack shaft 92. In addition, at the end of the support yoke 93 on the rack shaft 92 side, a groove portion 98 that is recessed in an arc shape corresponding to the back surface 92a of the rack shaft 92 opposite to the pinion shaft 97 side in the axial direction of the rack shaft 92. Is formed. The coil spring 94 is disposed in a compressed state between the cap 100 fixed to the external opening end 99 of the rack guide housing portion 96 and the support yoke 93, so that the support yoke 93 is placed on the rack shaft 92 side. It is configured to press.

JP-A-2005-41251 Japanese Utility Model Publication No. 4-31079

  By the way, the support yoke 93 is movably accommodated in the rack guide accommodating portion 96 as described above, and there is a slight gap between the outer peripheral surface of the support yoke 93 and the inner peripheral surface of the rack guide accommodating portion 96. S4 exists. In the above-described conventional configuration, the support yoke 93 having the groove 98 is merely pressed against the rack shaft 92, and the rack shaft 92 is the axis of the rack shaft 92 on the plane perpendicular to the width direction, that is, the contact / separation direction. Actually, it cannot be said that the swinging (swinging) in the direction orthogonal to the direction is sufficiently suppressed.

  Here, the rack teeth 101 formed on the rack shaft 92 and the pinion teeth 102 formed on the pinion shaft 97 are generally inclined teeth (helical gears) in order to ensure their smooth engagement. Therefore, a force in the width direction acts on the rack shaft 92 from the pinion shaft 97 as the rack shaft 92 reciprocates. Therefore, when a steering operation or the like is performed, a force in the width direction acts on the rack shaft 92 from the pinion shaft 97, so the rack shaft 92 may swing in the width direction. As a result, for example, the support yoke 93 may be tilted in the rack guide housing portion 96 to generate a hitting sound, and there is still room for improvement in this respect.

  Patent Document 2 discloses a steering device including a retainer that clamps a rack shaft from both sides in the width direction. However, in this retainer, the rack shaft is inclined in the width direction around the meshing portion with the pinion shaft due to the dimensional variation of the end bush (slide bearing) that slidably supports the shaft end of the rack shaft. In order to suppress this, it is provided at a position spaced apart from the meshing portion in the axial direction of the rack shaft. Accordingly, since the position where the retainer supports the rack shaft is separated from the position (meshing portion) where the force in the width direction acts on the rack shaft from the pinion shaft, the swing of the rack shaft is suppressed by the retainer. It is difficult. That is, the steering device described in Patent Document 2 does not solve the above problem.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a steering device that can stabilize the behavior of a rack shaft.

  In order to achieve the above object, the invention according to claim 1 is directed to a pinion shaft that is rotated by a steering operation, a rack shaft that is formed with rack teeth that mesh with pinion teeth formed on the pinion shaft, and the rack shaft. A rack guide mechanism that presses against the pinion shaft so as to be reciprocally movable in the axial direction of the rack shaft, and a rack housing in which a rack guide housing portion that houses the rack guide mechanism is formed, and the rack guide mechanism Has a support yoke and a pressing member that are accommodated in the rack guide accommodating portion, and the support yoke is pressed against the rack shaft by the pressing member in a contacting / separating direction that contacts and separates from the rack shaft. In the steering device provided so as to be movable, the pinion teeth and the rack teeth are each formed as oblique teeth. And a direction perpendicular to the axial direction of the rack shaft on a plane perpendicular to the contact / separation direction is defined as a width direction of the rack shaft, and sliding is performed on both sides in the width direction of the meshing portion of the rack shaft with the pinion shaft. The gist of the present invention is to have a pair of supporting pieces in contact with each other and supporting means fixed to the rack guide housing portion.

  According to the above configuration, the rack shaft is supported from both sides in the width direction of the rack shaft by the support pieces of the support means fixed to the rack guide housing portion. Therefore, unlike the case where the rack shaft is supported by the movable support yoke, the rack shaft can be sufficiently suppressed from swinging in the width direction. In the above configuration, since the support pieces are in sliding contact with both sides in the width direction of the meshing portion of the rack shaft with the pinion shaft, a force in the width direction acts on the rack shaft from the pinion shaft at the meshing portion by the reciprocation of the rack shaft. In this case, the rack shaft can be effectively prevented from swinging in the width direction. Therefore, the behavior of the rack shaft can be stabilized, and for example, the support yoke can be prevented from tilting in the rack guide housing portion, and the generation of abnormal noise can be suppressed.

  According to a second aspect of the present invention, in the steering apparatus according to the first aspect, the support means is fixed in the rack guide housing portion so that the support pieces are in close contact with the inner peripheral surface of the rack guide housing portion. This is the summary.

According to the above configuration, since the rack shaft is supported by the support piece that is in close contact with the inner peripheral surface of the rack guide housing portion, the rack shaft can be further suppressed from swinging in the width direction.
According to a third aspect of the present invention, in the steering apparatus according to the first or second aspect, the support means includes a cylindrical body that is disposed on an outer periphery of the support yoke and is fixed to the rack guide accommodating portion. The gist is that each of the support pieces is integrally formed with the cylindrical body.

  According to the above configuration, since the pair of support pieces are formed integrally with the cylindrical body disposed on the outer periphery of the support yoke, the number of parts is larger than when the support means is configured by a pair of support pieces made of different members. And a simple configuration can be achieved.

  ADVANTAGE OF THE INVENTION According to this invention, the steering apparatus which can stabilize the behavior of a rack shaft can be provided.

The schematic block diagram of an electric power steering device (EPS). Sectional drawing which shows the rack and pinion mechanism and peripheral structure of 1st Embodiment. The expanded sectional view which shows the rack guide mechanism of 1st Embodiment. The perspective view of the guide bush of 1st Embodiment. The expanded sectional view which shows the support piece vicinity in the guide bush of 1st Embodiment. The expanded sectional view which shows the rack guide mechanism of 2nd Embodiment. The perspective view of the guide bush of 2nd Embodiment. (A) The top view of the guide bush of 2nd Embodiment, (b) The front view of a sheet | seat member. The expanded sectional view which shows the support piece vicinity in the guide bush of another example. Sectional drawing which shows the conventional rack and pinion mechanism and peripheral structure.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, in an electric power steering apparatus (EPS) 1, a steering shaft 3 to which a steering 2 is fixed is connected to a rack shaft 5 via a rack and pinion mechanism 4. 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. Then, 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, so that the steering angle of the steered wheels 12 is increased. That is, the traveling direction of the vehicle is changed.

  The EPS 1 is configured as a so-called column assist type EPS that rotationally drives the column shaft 8 with 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 21 formed on the rack shaft 5 and pinion teeth 22 formed on the pinion shaft 10. The rack teeth 21 of the present embodiment are formed as oblique teeth (helical gears) whose teeth are inclined with respect to the axis of the rack shaft 5, and the pinion teeth 22 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 disposed within the substantially cylindrical rack housing 23 with a predetermined crossing angle with the pinion shaft 10. The EPS 1 is provided with a rack guide mechanism 24 that supports the rack shaft 5 so as to reciprocate in the axial direction of the rack shaft 5 while pressing the rack shaft 5 against the pinion shaft 10. The rack guide mechanism 24 keeps the backlash between the rack teeth 21 and the pinion teeth 22 properly, and suppresses the generation of rattling noise.

  Specifically, as shown in FIG. 2, the rack guide 23 is accommodated in the rack housing 23 with the rack shaft 5 sandwiched between the pinion accommodating portion 31 in which the pinion shaft 10 is accommodated and the pinion accommodating portion 31. A rack guide accommodating portion 32 is formed. The pinion accommodating portion 31 extends in the axial direction of the pinion shaft 10 and is formed in a cylindrical shape with one end (upper end in FIG. 2) opened. On the other hand, the rack guide accommodating portion 32 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 23 and the other end (the left end in FIG. 2). It is formed in a cylindrical shape that opens to the outside of the rack housing 23.

  The pinion shaft 10 is housed in the pinion housing portion 31 in such a manner that an upper end 10 a connected to the intermediate shaft 9 (see FIG. 1) protrudes from the pinion housing portion 31. The pinion shaft 10 is rotatably supported by bearings 33 and 34 provided in the pinion housing portion 31. The pinion teeth 22 are formed between a portion of the pinion shaft 10 supported by the bearing 33 and a portion supported by the bearing 34.

  As shown in FIGS. 2 and 3, the rack guide mechanism 24 includes a support yoke 41 that supports the rack shaft 5 so as to reciprocate in the axial direction, and a coil spring 42 as a pressing member that presses the support yoke 41 against the rack shaft 5. It has. The support yoke 41 is formed in a substantially cylindrical shape, and in the rack guide housing portion 32, the support yoke 41 is in a direction substantially perpendicular to the axial direction of the rack shaft 5 and the pinion shaft 10, that is, in contact with or separated from the rack shaft 5. It is housed so that it can move in the direction.

  Further, at the end of the support yoke 41 on the rack shaft 5 side, there is a back surface 5a opposite to the pinion shaft 10 side of the rack shaft 5 having a substantially circular cross section when viewed in the axial direction of the rack shaft 5. A corresponding arc-shaped groove 43 is formed, and an arc-shaped sheet member 44 that is a sliding contact surface when the rack shaft 5 is pressed is fixed to the groove 43. In the present embodiment, the support yoke 41 is formed of a metal material, and the sheet member 44 is formed by coating a metal plate with a resin made of a low friction material. On the other hand, a recess 45 is formed at the end of the support yoke 41 opposite to the rack shaft 5.

  The external opening end 46 that opens to the outside of the rack housing 23 in the rack guide accommodating portion 32 is closed by screwing a substantially disk-shaped cap 47. The coil spring 42 is disposed between the support yoke 41 and the cap 47 in a compressed state, and presses the support yoke 41 against the rack shaft 5. Specifically, one end of the coil spring 42 is seated on the bottom surface 45 a of the recess 45 provided in the support yoke 41, and the other end is seated on the inner surface 47 a of the cap 47. Thus, the support yoke 41 is configured to support the rack shaft 5 so as to be capable of reciprocating while pressing the rack shaft 5 against the pinion shaft 10 side.

(Behavior stabilization structure)
Next, a structure for stabilizing the behavior when the rack shaft reciprocates will be described.
Since the rack teeth 21 and the pinion teeth 22 are inclined as described above, the rack shaft 5 is racked in the width direction, that is, on a plane orthogonal to the contact / separation direction as the rack shaft 5 reciprocates. A force in a direction perpendicular to the axial direction of the shaft 5 acts from the pinion shaft 10. As a result, during steering operation or the like, a force in the width direction acts on the rack shaft 5 from the pinion shaft 10, and the rack shaft 5 swings in the width direction. There is a risk that a slapping sound may be generated.

In consideration of this point, the rack guide mechanism 24 includes a guide bush 51 as a support unit fixed to the rack guide housing portion 32.
More specifically, the rack guide accommodating portion 32 includes a large diameter portion 52 that constitutes the external opening end 46, and a small diameter portion 53 that is continuous with the large diameter portion 52 and has an inner diameter smaller than the inner diameter of the large diameter portion 52. Consists of.

  As shown in FIGS. 3 and 4, the guide bush 51 includes a cylindrical tubular body 55 disposed on the outer periphery of the support yoke 41, and the rack shaft 5 from the end of the tubular body 55 on the rack shaft 5 side. And a pair of support pieces 57 slidably in contact with both sides in the width direction of the meshing portion 56 of the rack shaft 5 with the pinion shaft 10. In the present embodiment, the guide bush 51 is made of a resin material.

  The cylindrical body 55 is formed in a cylindrical shape having a constant outer diameter and inner diameter, and the outer diameter is formed to be equal to the inner diameter of the small diameter portion 53. A plurality of (four in the present embodiment) extending portions 58 extending outward in the radial direction are formed at the end of the cylindrical body 55 opposite to the rack shaft 5. The guide bush 51 includes an extended portion 58 of the cylindrical body 55 between the large-diameter portion 52 and the stepped surface 59 of the small-diameter portion 53 and the C-shaped retaining ring 60 fixed to the large-diameter portion 52. By being clamped, the rack guide housing portion 32 is fixed.

  Further, the inner diameter of the cylindrical body 55 is slightly larger than the outer diameter of the support yoke 41, and a gap S1 is formed between the inner peripheral surface 55a of the cylindrical body 55 and the outer peripheral surface 41a of the support yoke 41. Is formed. A plurality (two in this embodiment) of annular mounting grooves 61 extending in the circumferential direction are formed on the outer peripheral surface 41a of the support yoke 41, and O-rings 62 are mounted in the mounting grooves 61, respectively. Yes.

  A gap S <b> 2 is formed between the cylindrical body 55 of the guide bush 51 and the back surface 5 a of the rack shaft 5. The gap S <b> 2 is formed such that the length along the contact / separation direction is larger than the length along the contact / separation direction in the gap S <b> 3 between the support yoke 41 and the cap 47. As a result, the rack shaft 5 collides with the guide bush 51 when the rack shaft 5 is displaced in a direction perpendicular to the axial direction of the rack shaft 5 and the pinion shaft 10 by the application of reverse input stress or the like, that is, in the contact / separation direction. It is supposed not to.

  Each support piece 57 is in sliding contact with the maximum width portion 63 where the length in the width direction of the rack shaft 5 is maximum. Since the rack shaft 5 has a substantially circular cross section as described above, both end portions in the width direction of the center O of the rack shaft 5 are the maximum width portions 63. The slidable contact surface 57 a of each support piece 57 with the rack shaft 5 is formed in a planar shape parallel to the contact / separation direction, and is in line contact with the rack shaft 5.

  As shown in FIG. 5, convex portions 64 projecting in the width direction of the rack shaft 5 are formed at positions facing the respective support pieces 57 on the inner peripheral surface 32 a of the rack guide housing portion 32. As a result, the distance L1 in the width direction of the rack shaft 5 at the position facing the support piece 57 on the inner peripheral surface 32a of the rack guide housing portion 32 is the width direction of the rack shaft 5 at the position facing the cylindrical body 55. Is smaller than the interval L2 (see FIG. 3). In FIG. 5, the convex portion 64 is exaggerated for convenience of explanation. The support piece 57 is in close contact with the inner peripheral surface 32 a of the rack guide housing portion 32 at the side surface 57 b opposite to the sliding contact surface 57 a. Note that the side surface 57 b is a curved surface having an arc cross section having the same diameter as the outer diameter of the cylindrical body 55.

  In the EPS 1 configured as described above, when the rack shaft 5 reciprocates by a steering operation or the like, even if a force in the width direction of the rack shaft 5 acts on the meshing portion 56 from the pinion shaft 10, Oscillation in the width direction is suppressed by the support piece 57 of the guide bush 51 fixed to the portion 32.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The rack guide mechanism 24 has a pair of support pieces 57 slidably in contact with both sides in the width direction of the meshing portion 56 of the rack shaft 5 with the pinion shaft 10 and is fixed in the rack guide housing portion 32. Equipped with.

  According to the above configuration, the rack shaft 5 is supported from both sides in the width direction of the rack shaft 5 by the support pieces 57 of the guide bush 51 fixed to the rack guide housing portion 32. Therefore, unlike the case where the rack shaft 5 is supported only by the movable support yoke 41, the rack shaft 5 can be sufficiently suppressed from swinging in the width direction. In the above configuration, since the support pieces 57 are in sliding contact with both sides in the width direction of the meshing portion 56 of the rack shaft 5 with the pinion shaft 10, the rack shaft 5 is reciprocated so that the meshing portion 56 is moved from the pinion shaft 10 to the rack shaft 5. When a force in the width direction acts on the rack shaft 5, it is possible to effectively suppress the rack shaft 5 from swinging in the width direction. Therefore, the behavior of the rack shaft 5 can be stabilized, and for example, the support yoke 41 can be prevented from tilting in the rack guide accommodating portion 32, and the generation of abnormal noise can be suppressed.

  (2) Since the guide bush 51 is fixed in the rack guide housing portion 32 so that the support pieces 57 are in close contact with the inner peripheral surface 32a of the rack guide housing portion 32, the rack shaft 5 swings in the width direction. This can be suppressed more.

  (3) Since each support piece 57 is integrally formed with the cylindrical body 55 that is disposed on the outer periphery of the support yoke 41 and is fixed to the rack guide housing portion 32, the number of parts can be reduced and the configuration can be simplified. it can.

  (4) By forming the convex portion 64 on the inner peripheral surface 32a of the rack guide accommodating portion 32, the width direction of the rack shaft 5 at a position facing the support piece 57 on the inner peripheral surface 32a of the rack guide accommodating portion 32. The interval L1 is made smaller than the interval L2 in the width direction of the rack shaft 5 at a position facing the cylindrical body 55. According to the above configuration, even if the cylindrical body 55, the rack guide housing portion 32, and the like have dimensional variations, the support piece 57 that supports the rack shaft 5 from both sides in the width direction and the inner peripheral surface 32a of the rack guide housing portion 32. It is possible to prevent a gap from being formed between the support pieces 57 and the inner peripheral surface 32a of the rack guide accommodating portion 32 to be in close contact with each other.

  (5) Since the support piece 57 is in sliding contact with the maximum width portion 63 having the maximum length in the width direction of the rack shaft 5, the rack shaft can be prevented from stably swinging in the width direction. become.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 6, in the rack guide mechanism 24 of this embodiment, the end of the support yoke 41 on the rack shaft 5 side is formed in a flat planar shape. On the other hand, a cylindrical positioning protrusion 71 protruding in the contact / separation direction is formed at the end of the support yoke 41 opposite to the rack shaft 5. The support yoke 41 is supported by a disc spring 72 as a pressing member disposed in a compressed state between the cap 47 fixed to the external opening end 46 of the rack guide housing portion 32 and the support yoke 41. It is pressed to the 5 side.

  Here, the rack guide mechanism 24 of this embodiment includes an annular spacer 73 that is fixed to the rack guide housing portion 32. When the cap 47 comes into contact with the spacer 73, the length along the contact / separation direction in the gap S3 between the support yoke 41 and the cap 47 becomes a preset length, and the disc spring 72 is preset. The predetermined amount is compressed.

  Specifically, the rack guide accommodating portion 32 is an intermediate portion between the large diameter portion 52 and the small diameter portion 53 that has an inner diameter that is smaller than the inner diameter of the large diameter portion 52 and larger than the inner diameter of the small diameter portion 53. 74. The spacer 73 has a cylindrical main body 75 having an outer diameter equal to the inner diameter of the large-diameter portion 52 and an inner diameter larger than the outer diameter of the disc spring 72, and a diameter from the end of the main body 75 on the rack shaft 5 side. It consists of the annular flange part 76 extended in the direction inner side. The inner diameter of the flange portion 76 is slightly larger than the outer diameter of the support yoke 41. The spacer 73 is fixed in the rack guide housing portion 32 with the end surface 73 a on the rack shaft 5 side in contact with the step surface 77 between the large diameter portion 52 and the intermediate portion 74.

  The disc spring 72 is fitted on the outer periphery of the positioning projection 71 of the support yoke 41 and is disposed in a compressed state between the support yoke 41 and the cap 47. Then, the cap 47 is screwed into the external opening end 46 of the rack guide housing portion 32 and abuts against the end surface 73b of the spacer 73 opposite to the rack shaft 5, whereby the disc spring 72 is compressed by a predetermined amount, and a desired pushing force is obtained. The pressure acts on the support yoke 41.

  The guide bush 51 is fixed in the rack guide accommodating portion 32 by the extension portion 58 being sandwiched between the stepped surface 78 between the intermediate portion 74 and the small diameter portion 53 and the spacer 73. As shown in FIGS. 6 and 7, the support piece 57 is provided with a sheet member 81 serving as a sliding contact surface when the rack shaft 5 is pressed. The sliding contact surface 81 a of the sheet member 81 with the rack shaft 5 is formed in a planar shape parallel to the contact / separation direction, and is in line contact with the rack shaft 5. Further, the sheet member 81 of the support piece 57 is in sliding contact with the maximum width portion 63 of the rack shaft 5 as in the first embodiment.

  Specifically, as shown in FIG. 8A, a through-hole 82 having a quadrangular cross section penetrating in the axial direction is formed at a position corresponding to the support piece 57 in the cylindrical body 55. A locking recess 83 extending in the axial direction of the rack shaft 5 is formed at the end of the through hole 82 opposite to the rack shaft 5. On the other hand, as shown in FIG. 8B, the sheet member 81 is formed in a rectangular plate shape corresponding to the through hole 82, and is inserted into the locking recess 83 at the end opposite to the rack shaft 5. A locking piece 84 is formed. The sheet member 81 is fixed to the guide bush 51 by being inserted into the through hole 82. The sheet member 81 is formed by coating a metal plate with a resin made of a low friction material.

As described above, according to this embodiment, in addition to the effects (1) to (5) of the first embodiment, the following effects can be achieved.
(6) By providing the support piece 57 with the sheet member 81 coated with a resin made of a low friction material, the sliding contact surface of the support piece 57 with the rack shaft 5 is made of the low friction material. Thereby, since the sliding resistance between the support piece 57 and the rack shaft 5 is reduced, the rack shaft 5 can smoothly reciprocate in the axial direction, and an excellent steering feeling can be realized. .

  (7) The rack guide housing portion 32 is provided with a spacer 73 that defines a gap S3 between the support yoke 41 and the cap 47 when the cap 47 comes into contact therewith. According to the above configuration, by fixing the cap 47 to the external opening end 46 of the rack guide housing portion 32 so as to contact the spacer 73, the disc spring 72 is compressed by a predetermined amount so that a desired pressing force is generated. Become. Thereby, the assembly | attachment property of the rack guide mechanism 24 can be improved. In addition, since the pressing force of the disc spring 72 can be easily changed by changing the size of the spacer 73 according to the specification of the vehicle and the like, while improving the assemblability, between vehicles with different specifications and the like. It becomes possible to make the shape of the rack housing 23 common.

In addition, the said embodiment can also be implemented in the following aspects which changed this suitably.
In the first embodiment, the support piece 57 is in slidable contact with the maximum width portion 63 of the rack shaft 5, but is not limited thereto, and may be slidably in contact with a portion other than the maximum width portion 63. Similarly, in the second embodiment, the sheet member 81 provided on the support piece 57 may be in sliding contact with a portion other than the maximum width portion 63 of the rack shaft 5.

  In the first embodiment, the guide bush 51 is fixed in the rack guide housing portion 32 using the retaining ring 60. However, the guide bush 51 is not limited thereto, and may be fixed using, for example, a disc spring.

  In the first embodiment, the slidable contact surface 57a of each support piece 57 with the rack shaft 5 is formed in a plane shape parallel to the contact / separation direction. A groove into which the maximum width portion 63 is inserted may be formed. Similarly, in the second embodiment, a groove into which the maximum width portion of the rack shaft 5 is inserted may be formed in the sliding contact surface 81a of the sheet member 81 with the rack shaft 5.

  In the second embodiment, the guide bush 51 is fixed in the rack guide housing portion 32 by the spacer 73. However, the present invention is not limited thereto, and a retaining ring is provided separately from the spacer 73, and the guide bush 51 is moved by the retaining ring. It may be fixed.

  In each of the above embodiments, by forming the convex portion 64 at a position facing the support piece 57 on the inner peripheral surface 32a of the rack guide housing portion 32, the support piece 57 on the inner peripheral surface 32a of the rack guide housing portion 32 and The distance L1 in the width direction of the rack shaft 5 at the facing position is made smaller than the distance L2 in the width direction of the rack shaft 5 at the position facing the cylindrical body 55. However, the present invention is not limited to this, and for example, the interval L1 is formed by forming the inner peripheral surface 32a of the rack guide accommodating portion 32 (small diameter portion 53) into a tapered shape having a smaller diameter from the outer opening end 46 side toward the inner side. You may make it become smaller than L2. Further, for example, the convex portion 64 may not be formed in the rack guide housing portion 32, and the convex portion may be formed on the side surface 57b of the support piece 57, or the outer peripheral surface of the cylindrical body 55 may be formed in a tapered shape. Further, the rack guide accommodating portion 32 may be formed so that the interval L1 and the interval L2 are equal without forming the convex portion 64.

  In each of the above embodiments, as shown in FIG. 9, the fitting groove 86 into which the convex portion 64 is inserted is formed on the side surface 57 b of the support piece 57 at a position facing the convex portion 64 of the rack guide housing portion 32. It may be formed. In this case, the guide bush 51 can be fixed to the rack guide housing portion 32 by appropriately setting the shape and size of the convex portion 64 and the fitting groove 86. Thereby, it becomes possible to omit the structure of the extension part 58 etc. for fixing the guide bush 51 in each said embodiment. In addition, not only the structure shown in FIG. 9 but a convex part may be formed in the side surface 57b of the support piece 57, and a fitting groove may be formed in the internal peripheral surface 32a of the rack guide accommodating part 32. FIG.

  In each of the above embodiments, the support piece 57 is in close contact with the inner peripheral surface 32a of the rack guide housing portion 32. However, the present invention is not limited to this, and for example, the support piece 57 is the inner peripheral surface 32a of the rack guide housing portion 32. You may make it protrude in the rack housing 23, without contacting.

  In each of the above embodiments, the mounting groove 61 in which the O-ring 62 is mounted is formed on the outer peripheral surface 41a of the support yoke 41. However, the present invention is not limited thereto, and a mounting groove is formed on the inner peripheral surface of the cylindrical body 55. Also good. Further, the O-ring 62 may not be interposed between the support yoke 41 and the cylindrical body 55.

  In each of the above-described embodiments, the support means is configured by the guide bush 51 including the cylindrical body 55 and the pair of support pieces 57 integrally formed with the cylindrical body 55. However, the present invention is not limited thereto, and a pair of separate members is included. You may comprise a support means with a support piece.

  In each of the above embodiments, the support yoke 41 is made of a metal material and the guide bush 51 is made of a resin material. However, the present invention is not limited thereto, and these may be made of other materials.

  In each of the above embodiments, the present invention is embodied in a steering device configured as a column assist type electric power steering device (EPS). However, the present invention is not limited to this, and the present invention may be applied to an EPS other than the column assist type such as a so-called rack assist type, a hydraulic power steering device, or a non-assist type steering device.

Next, technical ideas that can be understood from the above embodiments and other examples will be described below together with their effects.
(A) In the steering apparatus according to claim 3, the rack guide housing portion has an interval in the width direction of the rack shaft at a position facing the support piece on the inner peripheral surface of the rack guide housing portion. A steering device, wherein the steering device is formed to be smaller than a distance in a width direction of the rack shaft at a position facing the cylindrical body. According to the above configuration, a gap is formed between the support piece that supports the rack shaft from both sides in the width direction and the inner peripheral surface of the rack guide housing portion even if the cylindrical body, the rack guide housing portion, etc. have dimensional variations. It is possible to prevent this from happening, and the support piece can be brought into close contact with the inner peripheral surface of the rack guide housing portion.

  (B) In the steering apparatus according to any one of claims 1 to 3 and (A), the sliding surface of the support piece with the rack shaft is made of a material having a low coefficient of friction. A steering apparatus characterized by the above. According to the above configuration, since the sliding resistance between the support piece and the rack shaft is reduced, the rack shaft can smoothly reciprocate in the axial direction, and an excellent steering feeling can be realized. .

  (C) In the steering device according to any one of claims 1 to 3, and (a) and (b), the pressing member is fixed to the support yoke and an external opening end of the rack guide housing portion. The support yoke is pressed against the rack shaft by being compressed between the cap and the cap, and the rack guide housing portion is placed between the support yoke and the cap by contacting the cap. A steering device characterized in that a spacer for defining a gap is provided. According to the above configuration, by fixing the cap to the outer opening end of the rack guide housing portion so as to contact the spacer, the pressing member is compressed by a preset amount, and a desired pressing force is generated. . Thereby, the assembly | attachment property of a rack guide mechanism can be improved. In addition, since the pressing force of the pressing member can be easily changed by changing the size of the spacer according to the specifications of the vehicle, the rack housing can be used between vehicles having different specifications while improving the assemblability. Can be made common.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering device (EPS), 4 ... Rack and pinion mechanism, 5 ... Rack shaft, 10 ... Pinion shaft, 21 ... Rack tooth, 22 ... Pinion tooth, 23 ... Rack housing, 24 ... Rack guide mechanism, 31 ... Pinion housing part, 32 ... rack guide housing part, 32a, 55a ... inner peripheral surface, 41 ... support yoke, 42 ... coil spring, 43 ... groove part, 44,81 ... sheet member, 45 ... concave part, 46 ... external opening end, 47 ... cap, 51 ... guide bush, 52 ... large diameter part, 53 ... small diameter part, 55 ... cylindrical body, 56 ... meshing part, 57 ... support piece, 57a, 81a ... sliding contact surface, 57b ... side face, 63 ... outermost Large part, 64 ... convex part, 71 ... positioning protrusion, 72 ... disc spring, 73 ... spacer, 74 ... intermediate part, 86 ... fitting groove, L1, L2 ... interval, S1 to S3 ... gap.

Claims (3)

A pinion shaft that rotates by a steering operation, a rack shaft formed with rack teeth that mesh with pinion teeth formed on 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 that supports the rack guide mechanism, and a rack housing in which a rack guide housing portion that houses the rack guide mechanism is formed. The rack guide mechanism includes a support yoke and a pressing member that are housed in the rack guide housing portion. In the steering device, wherein the support yoke is provided so as to be movable in a contacting / separating direction contacting and separating from the rack shaft while being pressed by the pressing member by the pressing member.
The pinion teeth and the rack teeth are each formed as oblique teeth,
A pair of supports that are in sliding contact with both sides in the width direction of the meshing portion of the rack shaft with the pinion shaft, with a direction orthogonal to the axial direction of the rack shaft on a plane orthogonal to the contact and separation direction A steering apparatus having a piece and supporting means fixed to the rack guide housing portion. The steering apparatus according to claim 1, wherein
The steering device according to claim 1, wherein the support means is fixed in the rack guide housing portion so that the support pieces are in close contact with an inner peripheral surface of the rack guide housing portion. The steering apparatus according to claim 1 or 2,
The support means includes a cylindrical body that is disposed on an outer periphery of the support yoke and is fixed to the rack guide housing portion.
Each of the support pieces is integrally formed with the cylindrical body.

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