JP2013035383A - Steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent causing the indentation on the tooth flank of the engagement part of the pinion and the rack tooth when press fitting the bearing to the housing, while shortening the time to attach the pinion shaft to the housing.SOLUTION: When press fitting of a ball bearing 23 is completed, the assembly goods of the pinion shaft 107 and the ball bearing 23 are inserted in the housing 21 in the state that the phase of a tooth flank of the pinion 22 is positioned with reference to a positioning recessed part 107B, so that the tooth flank of the pinion 22 may contact with the tooth flank of the rack tooth 321 that faces to the recess of a thread part 33. Afterwards, if a positioning jig 37 is detached from a right end face of the rack shaft 31, the pinion 22 is rotated in the predetermined amount, and the rack tooth 32 is stopped by the intermediate position of the stroke, the assembling of the pinion shaft 107 to the housing 21 is completed.

Description

  The present invention relates to a steering device, and more particularly to a steering device that facilitates assembly of a pinion shaft of a rack and pinion type steering device.

  In a rack and pinion type steering device, a rack shaft that changes the steering angle of a wheel via a tie rod is supported by a housing of the steering gear so as to be able to reciprocate, and a pinion shaft that transmits the rotation of the steering wheel to the rack shaft is The housing is rotatably supported via a bearing.

  Such a rack and pinion type steering device applies a preload to a bearing that supports the pinion shaft in a housing, and the load applied to the pinion shaft during steering causes the pinion shaft to move in the radial direction or the thrust direction. And the steering force is prevented from fluctuating.

  Applying preload to the bearing with a ring nut is preferable because it increases the radial and thrust rigidity of the bearing, but it requires space to incorporate the ring nut. There is a problem that adjustment work takes time.

  If preload is applied to the bearing with a taper snap ring (retaining ring), the space for incorporating the taper snap ring can be reduced, so that the steering gear can be miniaturized and the assembly work time of the taper snap ring can be shortened. However, if a preload is applied to the bearing with the taper snap ring, the rigidity of the bearing in the radial direction and the thrust direction is reduced. In order to increase the rigidity of the bearing in the radial direction or thrust direction, the bearing may be press-fitted into the housing. However, when the bearing is press-fitted into the housing, a large load acts on the tooth surface of the meshing portion of the pinion and the rack teeth at the time of bearing press-fitting, resulting in indentation on the tooth surface of the meshing portion, and abnormal noise is generated during steering, There arises a problem that the durability of the steering gear is lowered.

  In the rack and pinion type steering device disclosed in Patent Document 1, an escape portion is formed by extending the bottom of the rack tooth to the outside of the stroke end on the rack shaft, and the escape portion is positioned at the position of the pinion. The nut is tightened. Therefore, even if the pinion shaft rotates, the rack shaft does not move, and the pinion shaft can be rotated as much as necessary to complete the tightening operation of the ring nut, thereby shortening the time for tightening the ring nut. .

  However, since the rack and pinion type steering device disclosed in Patent Document 1 applies a preload to the bearing with a ring nut, a space for incorporating the ring nut is required. The problem of time-consuming preload adjustment work has not been solved.

JP 2005-255121 A

  The present invention provides a rack and pinion type steering device that shortens the work time for assembling the pinion shaft to the housing and prevents the impression of the tooth surface of the meshing portion between the pinion and the rack teeth when the bearing is press-fitted into the housing. The issue is to provide. In addition, the present invention facilitates the operation of positioning the rack shaft in the neutral position after the pinion shaft is assembled to the housing, so that the steering angle detection device used in the electric power steering device, the vehicle attitude control device, etc. is neutral. It is an object of the present invention to provide a rack and pinion type steering device that enables accurate positioning at a position.

  The above problem is solved by the following means. That is, the first invention is a housing, a rack shaft that is supported by the housing so as to be able to reciprocate, and that changes the steering angle of the wheel via a tie rod, and an end of the rack shaft is pivotally supported by the housing so as to be able to reciprocate. A pinion shaft connected to the bearing bush and the steering wheel and meshing with the rack teeth of the rack shaft. The pinion shaft for transmitting the rotation of the steering wheel to the rack shaft. The shaft is press-fitted into the housing and the pinion shaft is rotatable to the housing. A bearing for supporting, a snap ring for fixing an outer ring of the bearing to the housing, a relief portion formed on the rack shaft and extending a bottom of the rack tooth from a stroke end of the rack shaft toward a center side of the rack shaft, Positioning that can be attached to the end surface of the rack shaft and that positions the relief portion on the axis of the pinion shaft. Jig, formed on the pinion shaft, and when the bearing fitted on the pinion shaft is press-fitted into the housing, so that the tooth surface of the pinion contacts the tooth surface of the rack tooth facing the relief portion. A steering device comprising a positioning recess for positioning the phase of the tooth surface of the pinion.

  According to a second aspect of the present invention, in the steering apparatus of the first aspect, the positioning recess abuts the outer periphery of the bolt shaft when the universal joint is fixed to the end of the pinion shaft with a bolt. This is a steering device for preventing the universal joint from coming out of the pinion, wherein the phase of the tooth surface of the pinion and the phase of the positioning recess are formed in a predetermined phase.

  According to a third invention, in the steering device of the second invention, when the escape portion is positioned on the axis of the pinion shaft, the end portion of the rack shaft is supported by the bearing bush. This is a steering device.

  According to a fourth invention, in the steering device according to the third invention, the rack shaft is induction-hardened on a tooth surface side in a range from the rack teeth to the relief portion. It is.

  A fifth invention is the steering device according to the fourth invention, wherein the rack shaft is induction-hardened on the back side in a range from the rack teeth to the relief portion. is there.

  In the steering device of the present invention, an outer ring of a bearing that is press-fitted into a housing and rotatably supports a pinion shaft on the housing is fixed to the housing with a snap ring, and the bottom of the rack tooth is extended from the stroke end of the rack shaft to the rack shaft. A relief part that extends toward the center is formed on the rack shaft, a positioning jig that positions the relief part on the axis of the pinion shaft is attached to the end surface of the rack shaft, and a bearing externally fitted to the pinion shaft is press-fitted into the housing In this case, a positioning recess for positioning the phase of the tooth surface of the pinion is formed in the pinion shaft so that the tooth surface of the pinion comes into contact with the tooth surface of the rack tooth facing the relief portion.

  Therefore, the work time for assembling the pinion shaft to the housing is shortened, and even if the bearing is press-fitted into the bearing hole, there is no indentation on the tooth surface of the meshing portion between the pinion and the rack teeth, and noise is generated during steering. There is no problem of lowering the durability of the steering gear. In addition, when the press-fit of the bearing is completed, the tooth surface of the pinion is in contact with the tooth surface of the rack tooth facing the relief part. Therefore, the pinion is rotated by a predetermined amount, and the rack tooth is accurately positioned at the intermediate position of the stroke. Can be stopped. Therefore, it is possible to accurately position the steering angle detection device used in the electric power steering device, the vehicle attitude control device, and the like at the neutral position.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall perspective view of a column assist type rack and pinion type steering device according to an embodiment of the present invention. FIG. 2 is a front view of a part of the main part of the steering gear of FIG. FIG. 3 is an enlarged front view, partly in section, showing a meshing portion between the rack and pinion of FIG. 2. (A) is a front view showing a state of a state just before the pinion shaft is assembled to the housing of the steering gear, (b) is an enlarged perspective view of the upper end of the pinion shaft of (a), and (c) is (a). It is the enlarged plan view seen from the arrow P direction. FIG. 5 is an enlarged cross-sectional view showing the main parts of the steering gear housing and pinion shaft of FIG. 4. FIG. 6 is a front view, partly in section, showing a state immediately after the pinion shaft is assembled to the steering gear housing. It is an AA expanded sectional view of FIG. (A) is a front view which shows the rack tooth vicinity of the rack shaft single-piece | unit of the Example of this invention, (b) is BB sectional drawing of (a). (A) is a front view which shows the whole rack shaft single-piece | unit of the Example of this invention, (b) is CC expanded sectional drawing of (a).

  FIG. 1 shows a steering apparatus according to an embodiment of the present invention, and is an overall perspective view of a column assist type rack and pinion type power steering apparatus. As shown in FIG. 1, the column assist type rack and pinion type power steering apparatus according to the embodiment of the present invention has a steering assist force of a motor 102 attached to an intermediate portion of a column 105 in order to reduce an operation force of a steering wheel 101. Is added to the steering shaft. Then, the rotation of the steering shaft is transmitted to the intermediate shaft 106, the rack shaft of the rack and pinion type steering gear 103 is reciprocated via the pinion shaft 107, and the steered wheel is steered via the tie rod 104.

  2 is a partially sectional front view showing the main part of the steering gear of FIG. 1, and FIG. 3 is an enlarged front view showing a part of the meshing portion of the rack and pinion in FIG. FIG. 4A is a front view showing a part of the state immediately before the pinion shaft is assembled to the housing of the steering gear, FIG. 4B is an enlarged perspective view of the upper end of the pinion shaft of FIG. 4 (c) is an enlarged plan view seen from the direction of arrow P in FIG. 4 (a).

  FIG. 5 is an enlarged cross-sectional view showing the main portions of the steering gear housing and pinion shaft of FIG. FIG. 6 is a front view, partly in section, showing a state immediately after the pinion shaft has been assembled to the housing of the steering gear, and FIG. 7 is an AA enlarged sectional view of FIG. FIG. 8A is a front view showing the vicinity of rack teeth of a single rack shaft according to the embodiment of the present invention, and FIG. 8B is a cross-sectional view taken along line BB in FIG. FIG. 9A is a front view showing the entire rack shaft according to the embodiment of the present invention, and FIG. 9B is an enlarged cross-sectional view taken along the line CC in FIG. 9A.

  The steering gear 103 according to the embodiment of the present invention is attached to a vehicle body frame (not shown) such as a front subframe. The front side orthogonal to the paper surface of FIG. 2 is the rear side of the vehicle body, the rear side orthogonal to the paper surface of FIG. 2 is the front side of the vehicle body, the left-right direction of FIG. 2 is the vehicle width direction, the upward direction of FIG. The direction is the vehicle body lower side.

  A rack shaft 31 is fitted in the inner periphery 211 of the housing 21 of the steering gear 103 so as to be slidable in the left-right direction in FIG. A bearing bush 212 is fitted into the left end of the inner periphery 211 of the housing 21, and the left end of the rack shaft 31 is slidably supported. Ball joint sockets (not shown) are screwed and attached to the left and right ends of the rack shaft 31, and tie rods 104 and 104 (see FIG. 1) connected to the ball joint sockets are connected to the wheels via knuckle arms (not shown). Has been.

  The housing 21 has body mounting bosses 213, 213, and 213 formed at three locations. The housing 21 is attached to the vehicle body frame by inserting a bolt (not shown) into a mounting hole (not shown) formed in the boss portions 213, 213, and 213 for mounting the vehicle body and fastening the bolt to the vehicle body frame.

  As shown in FIGS. 2 to 5, the pinion shaft 107 is rotatably supported on the housing 21 by a ball bearing (bearing) 23 at the upper portion 107 </ b> D of the pinion 22. A caulking ring 27 that is fitted into the groove 26 of the pinion shaft 107 and that is caulked sandwiches the inner ring of the ball bearing 23 between the stepped surface 28 of the pinion shaft 107. The outer ring of the ball bearing 23 is press-fitted into a bearing hole 214 formed in the housing 21 and is pressed in the axial direction by a taper snap ring (retaining ring) 29 attached to the annular groove 215 of the bearing hole 214. It is fixed to the housing 21. An inclined surface is formed on one side of the taper snap ring 29 and the annular groove 215. When the taper snap ring 29 is inserted into the annular groove 215, a gap between the outer ring of the ball bearing 23 is removed by the wedge action. A preload is applied to the ball bearing 23.

  A lower end 107C of the pinion shaft 107 is pivotally supported by the housing 21 by the needle bearing 24 so as to be rotatable only in the radial direction. A universal joint 108 in FIG. 1 is externally fitted and fixed to the male serration 107A at the upper end of the pinion shaft 107, and the pinion shaft 107 is connected to the intermediate shaft 106 through the universal joint 108. When the universal joint 108 is externally fitted to the male serration 107A and then fixed with a bolt (not shown), the positioning recess 107B formed in the male serration 107A comes into contact with the outer periphery of the shaft portion of the bolt and can be freely moved from the male serration 107A. The joint 108 is prevented from coming out. In the embodiment of the present invention, the phase of the tooth surface of the pinion 22 and the phase of the positioning recess 107B are formed to be a predetermined phase.

  That is, in the embodiment of the present invention, after the tooth surface of the pinion 22 is processed by rolling, the positioning recess 107B is processed so as to have a predetermined phase with respect to the tooth surface of the pinion 22. As another method, the positioning recess 107B is processed first, and the positioning recess 107B is set as a reference position when the tooth surface of the pinion 22 is processed by rolling, and the tooth surface of the pinion 22 is processed by rolling. May be. The rotation of the pinion shaft 107 is transmitted to the rack shaft 31 via the pinion 22 and changes the direction of the steered wheels via the tie rods 104 and 104 of FIG.

  As shown in FIGS. 8 and 9, the rack teeth 32 of the rack shaft 31 have the bottoms of the rack teeth 32 from the stroke end (usage range) to the center side of the rack shaft 31 (left side in FIGS. 8 and 9). A relief portion 33 extending toward the surface is formed. However, if the escape portion 33 is formed on the rack shaft 31, the strength of the rack shaft 31 may be reduced.

  As shown in FIG. 9, in order to increase the strength of the rack shaft 31, when the tooth surface in the range L5 where the rack teeth 32 are formed is induction-hardened, the range L6 of the escape portion 33 is also subjected to induction hardening. Thus, the range L7 from the rack tooth 32 to the relief portion 33 is induction hardened (induction hardening range 35 indicated by a two-dot chain line in FIG. 9).

  Further, if the outer periphery 34 on the back side of the rack shaft 31 is induction-quenched over a range L8 from the rack teeth 32 to the escape portion 33 (high-frequency hardening range 36 shown by a two-dot chain line in FIG. 9), This is preferable because the strength can be further increased. Further, either one of the induction hardening range 35 or the induction hardening range 36 may be induction hardened.

  The procedure for assembling the rack shaft 31 and the pinion shaft 107 to the housing 21 is as follows. That is, as shown in FIG. 4, a positioning jig 37 is attached to the right end surface of the rack shaft 31, and the positioning jig 37 is brought into contact with a stopper 38 as an assembly jig, so that the escape portion 33 of the rack shaft 31 is moved. Positioning is performed on the shaft center 25 of the pinion shaft 107. At this time, the rack shaft 31 moves to the right beyond the stroke end (usage range), and the left end portion of the rack shaft 31 is supported by the bearing bush 212.

  After the inner ring of the ball bearing 23 is press-fitted into the pinion shaft 107, the caulking ring 27 is caulked and mounted in the groove 26 of the pinion shaft 107, and the inner ring of the ball bearing 23 is fixed to the pinion shaft 107. Make 23 assemblies. After the needle bearing 24 is press-fitted into the housing 21, the assembly of the pinion shaft 107 and the ball bearing 23 is inserted into the housing 21 as shown in FIG. 4.

  As shown in FIG. 5, the bearing hole 214 of the housing 21 includes a press-fit portion 214A having an axial length L1 and a non-press-fit portion 214B having an axial length L2. That is, the inner diameter D1 of the press-fit portion 214A is formed smaller than the outer diameter D3 of the outer ring of the ball bearing 23, and the inner diameter D2 of the non-press-fit portion 214B and the non-press-fit portion 214C is larger than the outer diameter D3 of the outer ring of the ball bearing 23. Is also formed in a large diameter. In addition, since the annular groove 215 is processed after the inner diameter D2 of the non-press-fit portion is processed, the inner diameter D2 of the non-press-fit portions 214B and 214C is the same inner diameter D2.

  The length from the right end of the press-fit portion 214A to the right end of the needle of the needle bearing 24 is formed as L4. The length from the left end surface of the ball bearing 23 to the left end surface of the lower end portion 107C of the pinion shaft 107 is formed as L3. In the embodiment of the present invention, the length L3 is set longer than the length L4. Further, the length L5 from the right end of the press-fit portion 214A to the end surface of the housing 21 is formed longer than the length L6 of the ball bearing 23. Therefore, when the assembly of the pinion shaft 107 and the ball bearing 23 is inserted into the housing 21, the ball bearing 23 is guided to the non-press-fit portion 214C. Therefore, the lower end portion 107C of the pinion shaft 107 is easily inserted into the needle bearing. Subsequently, the lower end 107 </ b> C of the pinion shaft 107 is inserted into the needle of the needle bearing 24, and the outer ring of the ball bearing 23 is press-fitted into the press-fit portion 214 </ b> A of the bearing hole 214. Therefore, the ball bearing 23 can be press-fitted smoothly, and the lower end 107C of the pinion shaft 107 can be prevented from damaging the needle of the needle bearing 24.

  As shown in FIG. 6, when the press-fitting of the ball bearing 23 is completed, a tapered snap ring 29 is attached to the annular groove 215, and the outer ring of the ball bearing 23 is fixed to the housing 21. In the embodiment of the present invention, the phase of the tooth surface of the pinion 22 and the phase of the positioning recess 107B are formed to be a predetermined phase. Therefore, as shown in FIG. 7, when the press-fitting of the ball bearing 23 is completed, the positioning recess 107B is used as a reference so that the tooth surface of the pinion 22 contacts the tooth surface of the rack tooth 321 facing the escape portion 33. The assembly of the pinion shaft 107 and the ball bearing 23 is inserted into the housing 21 with the phase of the tooth surface of the pinion 22 positioned.

  Thereafter, the positioning jig 37 is removed from the right end surface of the rack shaft 31, the pinion 22 is rotated by a predetermined amount, and the rack teeth 32 are stopped at an intermediate position of the stroke, whereby the pinion shaft 107 is assembled to the housing 21. Complete. In the embodiment of the present invention, when the press-fitting of the ball bearing 23 is completed, the tooth surface of the pinion 22 is in contact with the tooth surface of the rack tooth 321 facing the escape portion 33, so that the pinion 22 is rotated by a predetermined amount. The rack teeth 32 can be accurately stopped at an intermediate position of the stroke. Therefore, it is possible to accurately position the steering angle detection device used in the electric power steering device, the vehicle attitude control device, and the like at the neutral position.

  In the embodiment of the present invention, since the outer ring of the ball bearing 23 is fixed to the housing 21 by the taper snap ring 29, the assembly work of the ball bearing 23 is easy, and the steering gear can be reduced in size. Further, the relief portion 33 is positioned at the axial center of the pinion shaft 107 so that the engagement between the pinion 22 and the rack teeth 32 is disengaged. Therefore, even if the ball bearing 23 is press-fitted into the bearing hole 214, there is no indentation on the tooth surface of the meshing portion between the pinion 22 and the rack teeth 32, noise is generated during steering, and the durability of the steering gear is improved. There is no problem of deteriorating.

  Further, when the escape portion 33 is positioned on the axis of the pinion shaft 107, the left end portion of the rack shaft 31 is maintained in a state where it is pivotally supported by the bearing bush 212. Therefore, since the rack shaft 31 does not move in the inner periphery 211 of the housing 21, after the ball bearing 23 is press-fitted into the bearing hole 214, the pinion 22 is rotated to easily move the rack shaft 31 to the left side.

  In the above-described embodiment, an example in which the present invention is applied to a column assist type rack and pinion type power steering apparatus has been described. However, the present invention may be applied to a pinion assist type rack and pinion type power steering apparatus and a manual type rack and pinion type steering apparatus.

DESCRIPTION OF SYMBOLS 101 Steering wheel 102 Motor 103 Steering gear 104 Tie rod 105 Column 106 Intermediate shaft 107 Pinion shaft 107A Male serration 107B Positioning recessed part 107C Lower end part 107D Upper part 108 Universal joint 21 Housing 211 Inner circumference 212 Bearing bush 213 Body mounting boss part 214 Bearing hole 214A Press-fit portion 214B Non-press-fit portion 214C Non-press-fit portion 215 Annular groove 22 Pinion 23 Ball bearing (bearing)
24 Needle Bearing 25 Shaft Center 26 Groove 27 Caulking Ring 28 Stepped Surface 29 Tapered Snap Ring 31 Rack Shaft 32 Rack Teeth 321 Rack Teeth Facing Relief 33 33 Relief Part 34 Backside Outer Side 35 High Frequency Hardening Range 36 Range 37 Positioning jig 38 Stopper

Claims (5)

housing,
A rack shaft that is supported by the housing so as to be reciprocally movable and changes a steering angle of a wheel via a tie rod;
A bearing bush for pivotally supporting the end of the rack shaft in the housing so as to be reciprocally movable;
A pinion shaft coupled to the steering wheel, the pinion meshing with the rack teeth of the rack shaft, and transmitting the rotation of the steering wheel to the rack shaft;
A bearing that is press-fitted into the housing and rotatably supports the pinion shaft in the housing;
A snap ring for fixing the outer ring of the bearing to the housing;
A relief part formed on the rack shaft and extending the bottom of the rack tooth from the stroke end of the rack shaft toward the center side of the rack shaft,
A positioning jig that can be attached to the end surface of the rack shaft and positions the relief portion on the axis of the pinion shaft;
When the bearing formed on the pinion shaft and externally fitted to the pinion shaft is press-fitted into the housing, the pinion tooth surface is brought into contact with the tooth surface of the rack tooth facing the relief portion. A steering apparatus comprising a positioning recess for positioning a tooth surface phase. The steering apparatus according to claim 1, wherein
The positioning recess is
When the universal joint is fixed to the end of the pinion shaft with a bolt, it comes into contact with the outer periphery of the shaft portion of the bolt and prevents the universal joint from coming out of the pinion shaft,
A steering device, wherein the phase of the tooth surface of the pinion and the phase of the positioning recess are formed in a predetermined phase. The steering apparatus according to claim 2, wherein
A steering apparatus, wherein the end portion of the rack shaft is supported by the bearing bush when the relief portion is positioned on the axis of the pinion shaft. In the steering apparatus according to claim 3,
A steering apparatus, wherein the rack shaft is induction-hardened on a tooth surface side in a range from a rack tooth to a relief portion. The steering apparatus according to claim 4, wherein
The steering device according to claim 1, wherein the rack shaft is induction-hardened on a back side in a range from the rack teeth to the relief portion.

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