JP5920583B2 - Steering device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a steering device such as an electric power steering device, and a manufacturing method thereof.

  In a vehicle steering apparatus, as a method of fixing a bearing to a column tube configured to rotatably support a steering shaft by a bearing, for example, Patent Document 1 discloses that a stopper portion and a pressing portion are pressed on a predetermined portion of the column tube. A pre-molding step in which a portion is formed by pressure molding, a fitting step in which a predetermined amount of a bearing is inserted into the column tube, and a post-molding step in which a predetermined portion of the column tube is pushed inwardly to restrict axial movement of the bearing. A method for fixing the bearing to the column tube has been proposed. This method is intended to reduce manufacturing costs and increase bearing performance and durability.

JP-A-11-342853

  However, the inventor conducted a detailed study on the conventional method for fixing the bearing to the column tube. First, it has been found that the cost reduction effect is not yet sufficient. That is, in order to carry out the method described in Patent Document 1, at least a press hole formation (opening formation) step in the column tube, a side end portion of the bearing in the insertion direction of the bearing into the column tube (end portion in the insertion direction) ) In the opening portion, the step of forming the pressing portion for pressing the bearing inward in the diameter of the column tube, the step of fitting the bearing into the column tube, and the bearing It is necessary to execute a step of press-molding a portion that regulates the side end portion of the bearing in the direction opposite to the insertion direction into the column tube (the end portion in the opposite insertion direction) into the opening. As described above, since the number of processes is large, man-hours are extended and manufacturing costs are increased.

  Further, as described above, since the end portion on the side opposite to the insertion direction is press-molded after the bearing is inserted into the column tube, a press pressure (load) is applied to the bearing, which may cause damage or deformation of the bearing. is there. If this happens, so-called “garbage” or the like is generated in the bearing, and there is a concern that the steering feeling (feeling) of the steering by the user may deteriorate, or the specification conditions may not be satisfied.

  Furthermore, as is clear from the illustration in Patent Document 1, the opening (hole) formed in the column tube is shaped to form a portion that regulates the end portion on the insertion direction side and the end portion on the counter insertion direction of the bearing. However, since the complicated shape of the opening is punched out by a press, the manufacturing cost of the mold for that purpose becomes expensive, which may further increase the manufacturing cost. Also, in that case, the shape of the mold becomes relatively complicated, and the shape tends to change over time as it is repeatedly used for press work, so it takes time to maintain the mold and compare the molds. May need to be replaced frequently. As a result, the manufacturing cost may be further increased.

  In addition, in order to insert (press-fit) the bearing into the column tube and form the press-fitted portion of the bearing, a press facility for that purpose is required, so that the equipment cost is also expensive. In addition, for forming the press-fit portion of the bearing, it is necessary to deform the column tube itself to hold the bearing. Therefore, the bearing is prevented from coming off along the axial direction of the column tube due to shape restrictions. There is a limit to increasing the tightening force. Furthermore, since the bearing is usually held by a column tube with high rigidity such as metal, it is difficult to sufficiently absorb and mitigate vibration and rattling transmitted through the column tube. There is a risk that the force will be further reduced. As a result, the steering feeling during driving may be deteriorated and noise may be generated.

  Therefore, the present invention has been made in view of such circumstances, and can further reduce the manufacturing cost and the equipment cost as compared with the prior art to improve the economy, and suppress damage and deformation of the bearing. In addition, an object of the present invention is to provide a steering device that can increase and maintain a bearing holding force and durability, and a manufacturing method thereof.

  In order to solve the above problems, a steering apparatus according to the present invention includes a steering wheel, a steering shaft fixed to the steering wheel, a column tube through which the steering shaft is inserted, and a column so as to rotatably support the steering shaft. And a bearing disposed in the tube.

  In addition to the configuration, the steering device according to the present invention has a belt-like shape, is wound around the peripheral wall of the column tube, and is radially tightened to tighten the bearing radially inward in the internal space of the column tube. And a fastener having an attaching portion and an axial holding portion for holding the bearing by restricting the movement of the bearing in the axial direction of the column tube. The radial tightening portion is fitted from the outside of the peripheral wall into the first opening (hole) formed in the peripheral wall of the column tube, and protrudes radially inward to contact the bearing. The first projection has a first projection, and the axial holding portion is fitted from the outside of the peripheral wall to the second opening formed in the peripheral wall of the column tube, and is projected inward in the radial direction. It has the 2nd convex part which engages with a bearing, and also the bearing is being fixed to the part in which those radial direction clamping parts and axial direction holding parts in a column tube were formed.

  In the steering device configured as described above, the bearing is disposed in the internal space of the column tube where the first opening and the second opening are formed, and in this state, the band-shaped (band-shaped) fastener is provided. The first convex portion and the second convex portion provided on the fastener are wound around the outer peripheral wall of the column tube, and the first convex portion and the second convex portion of the column tube are respectively connected to the first opening and the second opening of the column tube. It is fitted from the outside. As a result, when the first convex portion of the fastener comes into contact with the bearing and the second convex portion engages with the bearing, and the fastener is tightened from this state, the bearing is connected to the first convex portion. Fixed to be held by the column tube by being pressed toward the inside in the radial direction of the column tube at the part and tightened, and the movement of the column tube in the axial direction is restricted at the part of the second convex part. Is done. Thus, the steering shaft is rotatably supported on the column tube via the bearing.

  Such a portion including the first convex portion of the fastener functions as a radial tightening portion that tightens the bearing radially inward, and the portion including the second convex portion of the fastener is the bearing. By having a structure that functions as an axial holding portion that holds the bearing by restricting the movement of the column in the axial direction, the column tube is inserted into the column tube as in the method described in Patent Document 1 above. Furthermore, the press molding step can be omitted, and the manufacturing cost can be reduced by extending the number of steps.

  In addition, since the column tube does not need to be pressed after the bearing is inserted in this way, no pressing pressure (load) is applied to the bearing, resulting in damage or deformation of the bearing. Etc.

  Furthermore, in order to allow the portion including the first convex portion of the fastener to function as the radial tightening portion and to cause the portion including the second convex portion of the fastener to function as the axial holding portion, Although the first opening and the second opening for fitting the first convex portion and the second convex portion need to be drilled in the column tube, the shape of the opening is the first convex portion and the second convex portion. A simple shape matched to the convex portion may be used. Moreover, since it is only necessary to manage the processing accuracy of the dimensions, even when the first opening and the second opening are formed by punching with a press using a mold, the manufacturing cost of the mold is reduced. It can be made cheaper.

  Furthermore, only the second opening is formed in the column tube to form the axial holding portion (that is, unnecessary bending or the like is unnecessary), and the shape thereof is described in Patent Document 1. Since the shape of the bearing is not a complicated shape such as the part that regulates the end portion on the insertion direction side and the end portion on the opposite insertion direction side of the bearing, the opening formation can be replaced by, for example, laser processing instead of punching by press. . The same applies to the formation of the first opening for constituting the radial tightening portion. Therefore, in these cases, there is an advantage that a press punching die itself becomes unnecessary.

  In addition, as described above, the bearing is arranged at a predetermined portion of the column tube, and the bearing is fixed by a fastener, so there is no need to fit (press-fit) the bearing into the column tube. No press equipment is required. Further, it is not necessary to deform the column tube for fixing the bearing. Furthermore, the fastener can be formed of an appropriate material such as a resin or a composite of metal and resin in addition to a metal, and the shape thereof can be arbitrarily selected. Therefore, the tightening force that prevents the bearing from coming off along the axial direction of the column tube is adjusted as desired according to the radial tightening force (pressing force) and the material and shape of the fastener. This ensures and maintains a sufficient clamping force on the bearing.

  Furthermore, as described above, the fastener can be formed of an appropriate material and in an appropriate shape as long as it can exhibit a sufficient tightening force, and at least contacts the bearing. If a part is made of a fastener made of, for example, a resin having elasticity against assumed vibrations, vibrations and rattling transmitted through the column tube can be sufficiently absorbed and mitigated. As a result, the bearing holding force is further enhanced and the durability is improved.

  Further, as a more specific aspect of the steering device having the above-described configuration, the axial holding portion includes a third convex portion in which a part of the peripheral wall of the column tube is bent inward in the radial direction in the internal space of the column tube. What has it can be mentioned as a suitable example. In this case, the third convex portion can be easily formed, for example, by cutting a part of the peripheral wall of the column tube and bending the portion into the inside of the column tube with a press or the like.

  If it does in this way, positioning of the fixed position (axial holding position) in the column tube of a bearing can be performed more reliably. Further, as the second convex portion provided in the fastener for engaging the bearing and restricting the movement in the axial direction, for example, it is necessary to have a plurality of portions formed so as to sandwich the bearing. By using the three convex portions as a part of the axial holding portion, it is possible to replace a part of the second convex portion provided on the fastener. Thereby, it is useful also in the point which can simplify the structure of a fastener more.

  A method for manufacturing a steering device according to the present invention is a method for effectively manufacturing the above-described steering device according to the present invention. The method includes a first convex portion that is formed in a belt shape and protrudes on one surface side, and A step of preparing a fastener having a second convex portion projecting on the one surface side, a step of forming a first opening and a second opening in the peripheral wall of the column tube, and a first opening in the column tube And a step of disposing the bearing at a portion where the second opening is formed, and winding the fastener around the peripheral wall of the column tube, and the first protrusion and the second opening of the fastener are respectively provided on the first protrusion and the second opening. And the second convex part are fitted from the outside of the peripheral wall of the column tube, and the first convex part and the second convex part are projected inward in the radial direction in the inner space of the column tube. The process of making contact and fastening the fastener Thus, the portion including the first protrusion is caused to function as a radial tightening portion for tightening the bearing radially inward, and the portion including the second protrusion is disposed in the axial direction of the column tube. And a step of functioning as an axial holding portion for holding the bearing by restricting the movement of the bearing. As a result, the bearing is fixed to a portion of the column tube where the radial tightening portion and the axial holding portion are formed.

  More specifically, a part of the peripheral wall of the column tube is bent inward in the radial direction in the internal space of the column tube to form a third convex portion that functions as a part of the axial holding portion. I like it. Furthermore, as described above, in the step of forming the first opening and the second opening, it is preferable to form the first opening and / or the second opening by laser processing.

  According to the present invention, a belt-like fastener is wound around a column tube and fastened to form a radial fastening portion and an axial holding portion of the bearing, thereby fixing the bearing and simplifying the steering device. Therefore, it is possible to improve the economy by reducing the manufacturing cost and the equipment cost, and to suppress the damage and deformation of the bearing. Even when a mold is used when forming the axial holding portion, the manufacturing cost and maintenance management cost including replacement can be reduced, or the mold need not be used. Cost reduction can be realized. In addition, by using such fasteners, it is possible to achieve and maintain a sufficient tightening force on the bearing, and to sufficiently absorb and mitigate vibration and rattling transmitted through the column tube. As a result, the bearing retainability and durability can be further improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view (partially sectional view) schematically showing an overall configuration of a preferred embodiment (electric power steering device) according to a steering device according to the present invention. FIG. 2 is an enlarged view (partial cross-sectional view) showing a partial configuration of the electric power steering apparatus shown in FIG. 1. (A) and (B) are respectively a plan view and a side view (a cross-sectional view taken along line BB in (A)) showing a state in which a bearing is inserted into a column tube in the electric power steering apparatus shown in FIG. is there. (A) And (B) is the front view and back view which show schematically the structure of an example of the fastener used with the electric power steering apparatus shown in FIG. (A) And (B) is the front view and side view (BB sectional drawing in (A)) of the straight pipe which are the raw material pipes of the outer column of a column tube, respectively. FIGS. 5A to 5D are respectively a front view and a side view schematically showing a state after the first opening and the second opening are formed in the straight pipe shown in FIGS. (B-B line sectional view in (A)), top view, and bottom view. (A) thru | or (D) are the front views, the side view (BB sectional view in (A)) which shows the state after fixing a bearing to the outer column of a column tube, respectively, a top view, FIG. It is front sectional drawing which shows roughly another example of the fixation (fastening) structure of the bearing 40 used with the steering device by this invention.

  Hereinafter, embodiments of the present invention will be described in detail. The positional relationship such as up, down, left, and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios. Furthermore, the following embodiment is an illustration for explaining the present invention, and is not intended to limit the present invention only to the embodiment. Furthermore, the present invention can be variously modified without departing from the gist thereof.

  FIG. 1 is a front view (partially sectional view) schematically showing an overall configuration of a preferred embodiment of a steering apparatus according to the present invention. In the electric power steering apparatus 1, a steering shaft 12 having a steering wheel 11 fixed to the rear side of the vehicle body (right side in FIG. 1) is inserted into a tubular column tube 13; An assist device 20 for applying auxiliary torque to the steering shaft 12 and a steering gear 30 connected to the front side of the vehicle body of the steering shaft 12 (on the left side in FIG. 1) via a rack / pinion mechanism (not shown). ing.

  The center portion of the steering wheel 11 is fixed to one end portion of the steering shaft 12. For example, by providing a known tilt mechanism or telescopic (nesting) mechanism (not shown), the height direction of the steering wheel 11 (arrow Ya shown in the drawing). , Yb) and the vehicle body longitudinal direction (direction shown by the arrow Yc in the drawing and the opposite direction) are adjustable.

  The steering shaft 12 is formed by combining an outer shaft 12A and an inner shaft 12B so that rotational force can be transmitted and relative displacement in the axial direction can be achieved by, for example, coupling via spline engagement and synthetic resin. As a result, when an impact is applied in the axial direction due to a vehicle collision or the like, the outer shaft 12A and the inner shaft 12B break at the portion of the synthetic resin that couples them, and as a result, the overall length of the steering shaft 12 is reduced. It is configured to

  Further, the column tube 13 through which the steering shaft 12 is inserted is configured such that the outer column 13A and the inner column 13B are movably combined in a telescopic manner (nested shape). When an impact is applied, the entire length is reduced while absorbing energy from the impact. That is, the column tube 13 has a so-called collapsible structure.

  The inner column 13 </ b> B of the column tube 13 has a vehicle body front side end portion coupled and fixed to a vehicle body rear side end surface of the gear housing 21. On the other hand, the inner shaft 12B of the steering shaft 12 passes through the inside of the gear housing 21 at the front end of the vehicle body, and a worm wheel (not shown) provided inside the assist device 20 (a worm that is rotationally driven by an actuator or the like). For transmitting the rotation to the steering shaft 12).

  Further, the column tube 13 is supported by a support bracket 14 at a middle portion of the column tube 13 on a part of the vehicle body 18 (for example, a lower surface of a dashboard inside the vehicle). Further, a locking portion (not shown) is provided between the support bracket 14 and the vehicle body 18, and when an impact in the direction toward the front side of the vehicle body is applied to the support bracket 14, for example, the support bracket 14 is engaged with the engagement. It is configured to move away from the stop and move forward of the vehicle body. Similarly, the upper end portion of the gear housing 21 is also supported by a part of the vehicle body 18.

  The output shaft 19 provided at the vehicle body front end of the inner shaft 12B and arranged to protrude from the vehicle front end surface of the gear housing 21 is connected to the intermediate shaft 16 via the universal joint 15. Is connected to the rear end of the vehicle. An input shaft 31 of the steering gear 30 is connected to the vehicle front side end portion of the intermediate shaft 16 via another universal joint 17. For example, a pinion (not shown) is coupled to the input shaft 31, and a rack (not shown) fitted in the steering gear 30 so as to be reciprocally slidable is engaged with the pinion. With this structure, the rotation of the steering wheel 11 moves the tie rod 32, and the wheels (not shown) of the vehicle are steered. Further, the universal joints 15 and 17 can be provided with vibration absorbers for preventing vibration applied to the intermediate shaft 16 from the ground via the wheels from being transmitted to the steering wheel 11.

  Further, the assist device 20 is provided with a stator made of permanent magnets installed in a case 291 fixed to the gear housing 21 and an electric motor 29 including a rotor provided on the output shaft and disposed opposite to the stator. It has been. The electric motor 29 has a predetermined magnitude in a predetermined direction based on the direction and magnitude of the torque applied from the steering wheel 11 to the inner shaft 12B detected by a torque sensor (not shown) installed on the inner shaft 12B. Is configured to generate auxiliary torque.

  Here, FIG. 2 is an enlarged view (partial cross-sectional view) showing a partial configuration of the electric power steering apparatus 1 shown in FIG. In FIG. 2, illustration of “radial tightening portions” and “axial holding portions”, which will be described later, formed on the outer column 13 </ b> A of the column tube 13 is omitted. As shown in the figure, a bearing 40 in which a plurality of balls 43 are rotatably held between an inner race 41 and an outer race 42 is inserted into the rear end of the outer column 13A of the column tube 13 in the vehicle body. It is fitted. The outer shaft 12A of the steering shaft 12 is fixed by being inserted through the inner race 41 of the bearing 40, so that the bearing 40 rotatably supports the steering shaft 12. Thus, the steering shaft 12, the bearing 40, and the column tube 13 are coaxially disposed along the axial direction G of the column tube 13.

  3A and 3B are a plan view and a side view, respectively, showing a state in which the bearing 40 is inserted into the column tube 13 in the electric power steering apparatus 1 shown in FIG. 3A corresponds to a top view viewed from the vehicle body rear side end side in the axial direction G of FIG. 2, and is also an AA arrow view in FIG. 3B, and FIG. B) is also a cross-sectional view taken along line BB in FIG. Further, FIGS. 4A and 4B are a front view and a rear view, respectively, schematically showing a configuration of an example of a fastener used in the present embodiment.

  As shown in FIGS. 3A and 3B, the peripheral wall 131 of the outer column 13A of the column tube 13 has a band portion 70 provided with a radial tightening portion 71 and an axial holding portion 72. A band 7 (fastener) is wound. As shown in FIGS. 4A and 4B, the fastening band 7 has a band portion 70 extending from the head portion 7a in a substantially linear shape. On the front (front) surface 73 side (one surface side) of the band portion 70, a plurality of first convex portions are provided so as to protrude in the center in the width direction (direction orthogonal to the extending direction) of the band portion 70. 71a and a plurality of second convex portions 72u and 72s arranged opposite to the side edges in the width direction of the band portion 70 are alternately arranged at a predetermined interval (particularly, FIG. 3A and FIG. 4). (See (A)). In addition, the 1st convex part 71a has the shape where a part of band part 70 protruded from the back surface 74 side to the surface 73 side, and the recessed part 711 defines the back side of the 1st convex part 71a. Has been.

  A serration 75 composed of a plurality of fastening grooves arranged in parallel at equal intervals is formed on the back surface 74 of the band portion 70. Further, a fastening hole 7H (so-called “nail”) is formed in the head portion 7a. Is formed. As shown in FIG. 3A, in a state where the fastening band 7 is wound around the peripheral wall 131 of the outer column 13A of the column tube 13, the front end portion 7b (the end portion opposite to the head portion 7a) of the band portion 70 is formed. The fastening hole 7H is inserted, and the fastening groove of the serration 75 is hooked on the fastening hole 7H of the head portion 7a. As described above, the fastening band 7 has a so-called outside serration structure, and is provided with a locking mechanism that causes a so-called “return structure” between the fastening hole 7H and the tip 7b.

  On the other hand, the outer column 13A of the column tube 13 has a first opening 3a having a shape equivalent to the cross section of the first convex portion 71a of the band portion 70 along the peripheral wall 131, and a second portion of the band portion 70. The second openings 3u and 3s which have the same shape as the cross section of the convex portions 72u and 72s and which are opposed to each other at an equal distance from each other are alternately drilled. The first openings 3a and the second openings 3u and 3s are alternately spaced apart in the same manner as the arrangement intervals of the first and second convex portions 71a and 72u and 72s formed in the band portion 70, respectively. Has been placed.

  Then, as shown in FIGS. 3A and 3B, in a state where the fastening band 7 is wound around the peripheral wall 131 of the outer column 13A, the first opening 3a is opened from the outside of the peripheral wall 131 of the outer column 13A. The first convex portion 71a is inserted and fitted. As a result, the first convex portion 71a projects toward the radially inner side of the outer column 13A (recessed when viewed from the radially outer side), and the protruding end portion is the outer wall surface 42a of the outer race 42 of the bearing 40. And the bearing 40 is tightened radially inward. In this manner, the portion including the first convex portion 71 a in the band portion 70 of the fastener 7 functions as the radial tightening portion 71.

  Further, as shown in the figure, the second protrusions 72u and 72s are inserted and fitted into the second openings 3u and 3s from the outside of the peripheral wall 131 of the outer column 13A, respectively. As a result, the second convex portions 72u and 72s project toward the radially inner side of the outer column 13A (recessed when viewed from the radially outer side) and engage with the bearing 40 (the outer race 42 thereof). To do. Accordingly, the bearing 40 is held inside the column tube 13 so that the movement of the bearing 40 in the axial direction G of the column tube 13 is restricted. As described above, the portion including the second convex portions 72 u and 72 s in the band portion 70 of the fastener 7 functions as the axial direction holding portion 72.

  More specifically, of the second convex portions 72u and 72s of the axial direction holding portion 72, on the front end of the page in FIG. 3A (left side in FIG. 3B; that is, on the vehicle body rear side). The second projecting portion 72u located is in contact with the vehicle body rear side end surface 42u of the outer race 42 of the bearing 40, and is also the rear end of the paper surface in FIG. 3 (A) (the right side in FIG. 3 (B); That is, the second convex portion 72 s located on the vehicle body front side abuts on the vehicle body front side end surface 42 s of the outer race 42 of the bearing 40, and the bearing 40 is held therebetween.

Here, in order to secure the tightening allowance of the bearing 40, the height of the first convex portion 71a of the radial tightening portion 71 is the distance between its tip and the inner wall surface of the straight pipe 13A facing it (that is, the bearing). 40 is set to be smaller than the outer diameter of the bearing 40. On the other hand, the height of the second convex portions 72u and 72s of the axial direction holding portion 72 is such that the inner diameter at that portion is a bearing so that the vehicle body rear side end surface 42u and the vehicle body front side end surface 42s of the outer race 42 of the bearing 40 are engaged. It is set to be smaller than the outer diameter size of 40.
The distance between the second convex portions 72u and 72s of the axial direction holding portion 72 is the height (width) of the bearing 40, that is, between the vehicle body rear side end surface 42u and the vehicle body front side end surface 42s of the outer race 42 of the bearing 40. It is equivalent to or slightly larger than the length between. In the present embodiment, the width of the band portion 70 is set in accordance with the distance between the second convex portions 72u and 72s of the axial direction holding portion 72.

  In this way, the outer race 42 of the bearing 40 is fitted to the second convex portions 72u and 72s of the axial holding portion 72, and the radial tightening portion 71 including the first convex portion 71a described above. The bearing 40 is fixed to the portion of the outer column 13A of the column tube 13 where the radial tightening portion 71 and the axial holding portion 72 are formed, coupled with the radially inner tightening (pressing). ing.

  FIGS. 5A and 5B, FIGS. 6A to 6D, and FIGS. 7A to 7D show a part of an example of a procedure for manufacturing the electric steering apparatus 1 configured as described above. ) And will be described below. Here, a procedure until the column tube 13 is processed and the bearing 40 is fixed thereto, that is, a procedure until the state shown in FIGS. 3A and 3B occurs will be described in detail.

  First, a straight pipe that is a raw material pipe of the outer column 13A of the column tube 13 is prepared. 5A and 5B are respectively a front view and a side view of the straight pipe (a cross-sectional view taken along line BB in FIG. 5A). For convenience of explanation, the straight pipe and the column tube are also shown. 13 and the outer column 13A. As the straight pipe 13A (13), a pipe whose inner diameter is slightly larger than the outer diameter of the bearing 40 is used.

  Next, the first opening 3a and the second openings 3u and 3s are formed in the straight pipe 13A, for example, by punching by pressing or cutting by laser. 6A to 6D are respectively a front view and a side view schematically showing a state after the first opening 3a and the second openings 3u and 3s are formed in the straight pipe 13A. FIG. 4B is a cross-sectional view taken along line BB in FIG. As shown in the figure, the first opening 3a and the second openings 3u, 3s are alternately arranged at every predetermined angle (in this embodiment, every 60 °) on the plane orthogonal to the axial direction G of the straight pipe 13A. The peripheral wall is punched radially inward or cut along the outer periphery of the position where the bearing 40 is fixed in the straight pipe 13A so as to be formed in places. At this time, punching or cutting of a total of nine places may be performed simultaneously, or appropriate places may be divided into a plurality of times.

  Then, separately prepared from the open end 13H on the side where the first opening 3a and the second openings 3u, 3s of the outer column 13A of the column tube 13 in the state shown in FIGS. 6 (A) to 6 (D) are formed. The bearing 40 is loosely inserted. Then, the fastening band 7 shown in FIGS. 4 (A) and (B) is wound and fastened in the circumferential direction of the peripheral wall 131 so that the surface 73 is in contact with the outer surface of the peripheral wall 131 of the outer column 13A. The bearing 40 is fixed inside the outer column 13A. 7A to 7D are respectively a front view and a side view schematically showing a state after the bearing 40 is fixed to the outer column 13A of the column tube 13 (a line BB in FIG. 7A). Sectional view), top view, and bottom view.

  At this time, the first convex portion 71a in the radial tightening portion 71 and the second convex portions 72u and 72s in the axial direction holding portion 72 that are convexly provided on the surface 73 of the fastening band 7 are respectively connected to the outer column. From the outside of the peripheral wall 131 of 13A, it is fitted into the first opening 3a and the second openings 3u, 3s, further pushed in, and further projected toward the inner space side of the outer column 13A. Thus, the first convex portion 71a is brought into contact with the outer wall surface 42a of the outer race 42 of the bearing 40, and the second convex portions 72u and 72s are engaged so as to sandwich the outer race 42 of the bearing 40, The bearing 40 loosely inserted into the outer column 13A is temporarily fixed. Then, the end portion 7b of the band portion 70 of the fastening band 7 is inserted into the fastening hole 7H of the head portion 7a, and the end portion 7b is pulled so as to have a predetermined tightening torque, for example. The tightening of the outer race 42 by the portion 71a is strengthened, and the engagement between the second convex portions 72u and 72s and the outer race 42 becomes deeper and stronger. In this state, the bearing 40 is tightened inward in the radial direction, and movement of the column tube 13 in the axial direction G is restricted.

  According to the electric power steering apparatus 1 and the manufacturing method thereof configured as described above, after the bearing 40 is loosely inserted into the outer column 13A of the column tube 13, the fastening band 7 is wound from the outside of the outer column 13A, Since the bearing 40 is fixed to the portion by fastening the bearing 40, the bearing 40 is fitted into the column tube 13, and then the column tube 13 is further press-molded. Thus, the number of steps can be reduced, and as a result, the number of steps can be extended and the manufacturing cost can be reduced.

  In addition, since the electric power steering apparatus 1 has a structure that does not require pressing of the column tube 13 after the bearing 40 is inserted, there is no possibility that a pressing pressure (load) is applied to the bearing 40. Thereby, it is possible to prevent the bearing 40 from being damaged or deformed.

  Furthermore, the part including the first convex part 71 a of the fastening band 7 functions as the radial tightening part 71, and the part including the second convex parts 71 u and 72 s of the fastening band 7 is used as the axial holding part 72. Although it is necessary to drill the first opening 3a and the second openings 3u and 3s into which the first protrusion 71a and the second protrusions 72u and 72s are fitted in order to function, those The opening shape may be a simple shape corresponding to the first convex portion 71a and the second convex portions 72u and 72s having a simple shape having a convex shape and a rectangular cross section. In addition, since it is only necessary to manage the processing accuracy of the dimensions, even when the first opening 3a and the second openings 3u and 3s are formed by punching with a press using a mold, the mold is used. The production cost can be reduced. Thereby, the manufacturing cost of the electric power steering apparatus 1 can be further reduced, and the economy can be further improved.

  Furthermore, only the second openings 3u and 3s are processed and formed in the outer column 13A of the column tube 13 in order to form the axial holding portion 72, as in the prior art described in Patent Document 1 and the like. Since complicated bending or the like is not required and the shape itself is simple, the opening can be replaced by, for example, laser processing, as described above, instead of punching by pressing. The same applies to the processing and formation of the first opening 3a for constituting the radial tightening portion 71. Therefore, in those cases, the press punching die itself is not necessary, so that the manufacturing cost of the electric power steering apparatus 1 can be further reduced and the economy can be further improved.

  Further, since the bearing 40 is disposed at a predetermined portion of the outer column 13A of the column tube 13 and the bearing 40 is fixed by the fastening band 7, it is not necessary to fit (press-fit) the bearing 40 into the column tube 13. This eliminates the need for a press facility for bearing press-fitting, and can reduce facility costs. Further, since it is not necessary to process and deform the column tube 13 for fixing the bearing 40, a pressing facility and a process for that purpose are also unnecessary, and thereby further improvement in economic efficiency can be achieved.

  Furthermore, the fastening band 7 can be formed of an appropriate material such as a resin or a composite of a metal and a resin in addition to a metal, and the shape thereof can be arbitrarily selected. Therefore, the tightening force that prevents the bearing 40 from coming off along the axial direction of the column tube 13 includes the radial tightening force (pressing force; friction due to the tightening force), the material of the fastener, It can be adjusted as desired according to the shape and the like (shearing force in the axial holding portion of the fastener), and thereby, a sufficient tightening force for the bearing can be secured and maintained.

  Furthermore, as described above, the fastening band 7 can be formed of an appropriate material and in an appropriate shape as long as a sufficient tightening force can be expressed. For example, by using a fastening band 7 formed of a resin or the like that has elasticity with respect to the assumed vibration or the like, the contacted part sufficiently absorbs or mitigates vibration or rattling transmitted through the column tube 13. As a result, the holding force of the bearing 40 can be further increased, and the durability can be improved.

  Furthermore, the second convex portions 72u and 72s constituting the axial direction holding portion 72 and the vehicle body rear side end surface 42u and the vehicle body front side end surface 42s of the outer race 42 in the bearing 40 constitute the outer column 13A of the column tube 13. A predetermined length along the circumferential direction (the width of the second protrusions 72u and 72s and the width of the second openings 3u and 3s in the circumferential direction) continuously contact each other. There is an advantage that the bearing 40 is less likely to be detached from the outer column 13A as compared with the case where the two are combined.

  FIG. 8 is a front sectional view schematically showing another example of a bearing fixing (fastening) structure used in the steering device according to the present invention. The bearing 40 fixing structure shown in FIG. 8 does not form the second opening 3 s in the outer column 13 A, forms the third protrusion 133 in the outer column 13 A, and replaces the fastening band 7 with the fastening band 8. Except for the provision of (fasteners), the bearing 40 is configured in the same manner as the bearing 40 fixing structure shown in FIGS. 3 (A) and 3 (B).

  The fastening band 8 has a first convex portion 81a having a smaller shape instead of the first convex portion 71a, and has only the second convex portion 72u among the second convex portions 72s and 72u. Except for this, a band unit 80 configured in the same manner as the band unit 70 shown in FIGS. 4A and 4B is provided. In this aspect, the radial tightening portion 81 is configured from a portion including the first convex portion 81a. Further, the third convex portion 133 is obtained by bending (bending) a part of the peripheral wall 131 of the outer column 13A of the column tube 13 toward the radially inner side in the inner space of the outer column 13A. It functions as a part of the axial holding portion 82 together with the eighth second convex portion 72u. Note that an opening 135 is defined at a site where the third convex portion 133 is formed.

  The steering device having the bearing 40 fixing structure shown in FIG. 8 also has the same effect as that of the electric power steering device 1 described above (details here are to avoid redundant description). (Omitted). In addition to this, when the bearing 40 is loosely inserted into the outer column 13A, the outer wall surface 42a of the outer race 42 of the bearing 40 is locked to the third convex portion 133. The fixed position (holding position in the axial direction) can be positioned more reliably. Further, by using the third convex part 133 as a part of the axial direction holding part 82, a part of the second convex part provided in the fastening band 8 can be replaced by that, so that the structure of the fastening band 8 can be changed. It can be simplified further.

  In addition, as above-mentioned, this invention is not limited to said embodiment, A various deformation | transformation is possible in the limit which does not change the summary. For example, the number of the radial tightening portions 71 and the axial holding portions 72 is not limited to three as shown in the drawing, and any number may be formed at least two. Further, the formation locations of the radial tightening portion 71 and the axial holding portion 72 are not limited to equiangular intervals. Furthermore, the first convex portion 71a and the second convex portions 72u and 72s, and the shapes of the first opening 3a and the second openings 3u and 3s corresponding to the first convex portion 71a and the second convex portions 72u and 72s are the radial tightening portion 71 and the axial direction holding. If the function of the part 72 is expressed, for example, an arbitrary shape such as a circular cross section or an elliptical cross section can be appropriately employed. Furthermore, the overall configuration of the steering device is not limited to the configuration exemplified as the electric power steering device 1.

  As described above, the steering device and the manufacturing method thereof according to the present invention can improve the economic efficiency by reducing the manufacturing cost and the equipment cost, and can suppress damage and deformation of the bearing. Since the bearing retainability and durability can be further improved, the present invention can be widely and effectively used for, for example, general vehicles equipped with a steering device and their manufacture.

1 Electric power steering device (steering device)
3a 1st opening 3u, 3s 2nd opening 7, 8 Fastening band (fastener)
7a Head portion 7b End portion 7H Fastening hole 11 Steering wheel 12 Steering shaft 12A Outer shaft 12B Inner shaft 13 Column tube 13A Outer column, straight tube 13B Inner column 13H Outer column open end 131 Outer column peripheral wall 133 Third convex portion 135 Opening 14 Support bracket 15, 17 Universal joint 16 Intermediate shaft 18 Car body 19 Output shaft 20 Assist device 21 Gear housing 29 Electric motor 291 Case 30 Steering gear 31 Input shaft 32 Tie rod 40 Bearing 41 Inner race 42 Outer race 42a Outside outer race Wall surface 42u Outer race vehicle rear end surface 42s Outer race vehicle front end surface 43 Ball 70, 80 Band portion 71, 81 Radial tightening portion 7 a, 81a first protrusion 72 and 82 axially holding portion 72u, the axial direction of the rear surface 75 serrations G column tube table (Table) surface 74 band portion of the second convex portion 73 band portion 72s

Claims (5)

A steering wheel,
A steering shaft fixed to the steering wheel;
A column tube through which the steering shaft is inserted;
A bearing disposed in the column tube to rotatably support the steering shaft;
A belt-shaped, wound around the peripheral wall of the column tube, and a radial tightening portion for tightening the bearing radially inward in the internal space of the column tube, and an axial direction of the column tube A fastener having an axial holding portion for holding the bearing by restricting movement of the bearing;
With
The radial tightening portion is fitted into a first opening formed in the peripheral wall of the column tube from the outside of the peripheral wall, and protrudes inward in the radial direction to abut against the bearing. 1 convex portion,
The axial holding portion is fitted into a second opening formed in the peripheral wall of the column tube from the outside of the peripheral wall, and protrudes radially inward to engage with the bearing. Has two convex parts,
The bearing is fixed to a portion of the column tube where the radial tightening portion and the axial holding portion are formed.
Steering device. The axial holding portion has a third convex portion in which a part of the peripheral wall of the column tube is bent inward in the radial direction in the internal space of the column tube.
The steering apparatus according to claim 1. A steering wheel, a steering shaft fixed to the steering wheel, a column tube through which the steering shaft is inserted, and a method of manufacturing a steering device including a bearing fitted to the column tube and rotatably supporting the steering shaft Because
Providing a fastener having a belt-like shape and having a first convex portion projecting on one surface side and a second convex portion projecting on the one surface side;
Forming a first opening and a second opening in the peripheral wall of the column tube;
Disposing the bearing at a site where the first opening and the second opening are formed in the column tube;
The fastener is wound around a peripheral wall of the column tube, and the first and second protrusions of the fastener are respectively placed on the outer side of the peripheral wall in the first opening and the second opening. A step of projecting the first convex portion and the second convex portion toward the radially inner side in the inner space of the column tube and contacting the bearing;
By fastening the fastener, the portion including the first convex portion functions as a radial tightening portion that tightens the bearing toward the radially inner side, and includes the second convex portion. A step of regulating the movement of the bearing in the axial direction of the column tube to function as an axial holding portion that holds the bearing;
Manufacturing method of steering apparatus having Bending a part of the peripheral wall of the column tube inward in the radial direction in the internal space of the column tube to form a third convex portion that functions as a part of the axial holding portion;
A method for manufacturing a steering device according to claim 3. In the step of forming the first opening and the second opening, the first opening and / or the second opening is formed by laser processing.
The method for manufacturing a steering device according to claim 3 or 4.

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