JP4548902B2 - Rack and pinion type steering device - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a rack and pinion type steering apparatus.
[0002]
[Prior art]
A conventional rack and pinion type steering device is disclosed in Japanese Patent Laid-Open No. 10-217984. In this rack and pinion type steering apparatus, as shown in FIGS. 5 to 7, a pinion 92 is provided at the tip of a steering shaft 91 coupled to the steering wheel 90, and the pinion 92 rotates together with the steering shaft 91. It is like that. A rack bar 93 extending in the longitudinal direction is engaged with the pinion 92.
[0003]
The pinion 92 and the rack bar 93 are accommodated in a housing 95. As shown in FIG. 7, the housing 95 has a boss portion 95a on the opposite side of the pinion 92 with the rack bar 93 interposed therebetween. . A rack guide 96 is provided in the boss portion 95a of the housing 95 so as to be movable in the axial direction. The rack guide 96 moves the rack bar 93 to the pinion 92 side by a biasing force of a coil spring 97 as a biasing means. Is energized.
[0004]
In addition, a sheet 98 is provided on the end surface of the rack guide 96 on the rack bar 93 side so as not to drop off. That is, as shown in FIG. 10, the rack guide 96 has a recess 96b having an inner peripheral surface formed by a cylindrical surface 96a at the center of the end surface on the rack bar 93 side. On the other hand, as shown in FIG. 11, the sheet 98 includes a steel portion 98a made of an iron-based metal, a copper sintered portion 98b integrally provided on one surface of the steel portion 98a, and a surface of the copper sintered portion 98b. And a coating portion 98c made of polytetrafluoroethylene (PTFE). This sheet 98 is obtained by drawing a material comprising a steel portion 98a, a copper sintered portion 98b and a coating portion 98c together with the press work, and as shown in FIG. 9A, the base obtained by the press work. The convex part 98e is protruded from 98d. As shown in FIG. 10, the convex portion 98 e has a cylindrical surface 98 f whose outer peripheral surface engages with the concave portion 96 b of the rack guide 96. Further, as shown in FIG. 8, the sliding surface of the seat 98 with the rack bar 93 extends in the width direction (vertical direction in the figure) perpendicular to the axial direction and the longitudinal direction, and corresponds to the convex portion 98e. An oil groove 98h that can intersect with a portion to be formed, here, an oil groove 98h that can intersect with a drawn hole 98g generated in the convex portion 98e during drawing.
[0005]
In such a rack and pinion type steering device, the rotation of the steering wheel 90 is converted into a linear motion of the rack bar 93 via the steering shaft 91 and the pinion 92, and thereby the steering angle of the tire 94 is changed. At this time, the rack guide 96 guides the rack bar 93 in the longitudinal direction while securing the engagement between the pinion 92 and the rack bar 93 together with the urging force of the coil spring 97. In addition, the seat 98 reduces the sliding frictional force between the rack bar 93 and the rack guide 96 in a state in which the seat 98 is prevented from falling off due to the engagement between the concave portion 96b of the rack guide 96 and the convex portion 98e. Yes.
[0006]
[Problems to be solved by the invention]
However, in the above conventional rack and pinion type steering device, when the seat 98 is prevented from falling off due to the engagement between the convex portion 98e of the seat 98 and the concave portion 96b of the rack guide 96, the durability of the seat 98 is improved. It became clear that there was concern.
[0007]
That is, in such a rack and pinion type steering apparatus, helical gears are adopted as the pinion 92 and the rack bar 93 as shown in FIG. 6 for power transmission and quietness. For this reason, a vertical force F <b> 1 in the drawing acts between the tooth surface of the pinion 92 and the tooth surface of the rack bar 93. Such a direction is a width direction orthogonal to the axial direction which is the moving direction of the rack guide 96 shown in FIG. 7 and the longitudinal direction of the rack bar 93.
[0008]
Further, in this rack and pinion type steering apparatus, due to the road surface reaction force acting on the tire 94 when the vehicle travels, as shown in FIG. 6, the rack bar 93 also applies a repeated force F2 in the width direction. receive.
[0009]
These forces F1 and F2 act so that the rack bar 93 bends the convex portion 98e of the sheet 98 in the width direction. Here, as shown in FIG. 9B, if the convex portion 98e protrudes without a curvature radius with respect to the base portion 98d (so-called pin angle of R = 0 (mm)), the bending thereof The stress will be concentrated at the boundary. For this reason, when such a sheet 98 is employed, the durability of the sheet 98 is a concern.
[0010]
In particular, as shown in FIG. 8, when the sheet 98 has an oil groove 98h to improve the slidability of the rack bar 93, the oil groove 98h communicates with the throttle hole 98g as shown in FIG. 9B. If so, the thickness t of the boundary between the convex portion 98e and the base portion 98d is extremely thin. For this reason, in this case, the strength tends to be weakened, and the durability of the sheet 98 is further concerned.
[0011]
The present invention has been made in view of the above-described conventional situation, and improves the durability of the sheet when the sheet is prevented from falling off by engagement between the convex part of the sheet and the concave part of the rack guide. It is an object to be solved to provide a rack-and-pinion steering device.
[0012]
[Means for Solving the Problems]
The rack and pinion type steering device of the present invention is provided at the tip of a steering shaft, meshes with the pinion rotating together with the steering shaft, and converts the rotational motion of the steering shaft into linear motion in the longitudinal direction. A rack bar that changes the steering angle, a housing that houses the pinion and the rack bar, and has a boss portion on the opposite side of the pinion across the rack bar, and an axial direction within the boss portion of the housing A rack guide that is movably provided and biases the rack bar toward the pinion by the biasing force of the biasing means, and guides the rack bar in the longitudinal direction, and an end surface of the rack guide on the rack bar side And a seat that reduces sliding frictional force between the rack bar and the rack guide. Has a recess in the center of the end face of the rack bar side, the sheet is protruded from the base portion, the rack-and-pinion type steering apparatus having a convex portion engaged with the concave portion,
[0013]
Boundary between the convex portion and the base portion of the sheet is configured to have a radius of curvature in the width direction orthogonal to the previous SL-axis direction and the longitudinal direction, has a radius of curvature in the longitudinal direction, the width direction The radius of curvature is larger than the radius of curvature in the longitudinal direction .
[0014]
In the rack and pinion type steering apparatus of the present invention, the sheet is prevented from falling off by engagement between the convex portion of the seat and the concave portion of the rack guide. Here, in this sheet, since the boundary between the convex portion and the base portion has a radius of curvature at least in the width direction, bending stress in the width direction does not concentrate on the boundary due to the shape effect. For this reason, the sheet exhibits high durability.
[0015]
Boundary between the convex portion and the base portion has a radius of curvature in the longitudinal direction, it has a size of curvature radius than the longitudinal curvature radius in the width direction. In the longitudinal direction, shear stress due to the guide of the rack bar acts, and this shear stress is smaller than the bending stress acting in the width direction. For this reason, if the sheet disperses the shear stress by the curvature radius in the longitudinal direction and the bending stress by the curvature radius in the width direction, the sheet can exhibit higher durability.
[0016]
When an oil groove extending in the width direction and intersecting with the portion corresponding to the convex portion is formed on the sliding surface of the seat with the rack bar, the oil groove is separated from the portion. Is preferred. If it is like this, the thickness of the boundary with the base part in a convex part will become thick, and it will be easy to ensure sufficient intensity | strength. For this reason, the sheet can exhibit higher durability.
[0017]
Therefore, in the rack and pinion type steering apparatus of the present invention, the seat can exhibit high durability, so that the safety and durability of the vehicle can be improved.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings.
[0019]
In the rack and pinion type steering apparatus of the embodiment, the seat 1 shown in FIGS. As shown in FIGS. 2A and 3A, the sheet 1 has a protruding portion 1b protruding from a base portion 1a obtained by pressing a material. Further, as shown in FIGS. 1 and 2A, the sheet 1 extends in the width direction (vertical direction in the drawing) orthogonal to the axial direction and the longitudinal direction, and corresponds to the convex portion 1b, that is, It has an oil groove 1d that can intersect with a drawn hole 1c generated in the convex portion 1b during drawing.
[0020]
As shown in FIG. 2B, the boundary between the convex portion 1b and the base portion 1a has a curvature radius in the width direction (R1 is, for example, 0.5 (mm) or more). Further, as shown in FIG. 3B, the boundary between the convex portion 1b and the base portion 1a also has a radius of curvature in the longitudinal direction (R2 is, for example, 0.5 (mm) or less). The curvature radius R1 in the width direction is larger than the curvature radius R2 in the longitudinal direction. As shown in FIGS. 1 and 2A, the oil groove 1d is separated from the throttle hole 1c.
[0021]
Other configurations of the rack and pinion type steering device are the same as the conventional ones shown in FIGS. 5 to 7, 10, and 11. For this reason, the same code | symbol is attached | subjected about the same structure and detailed description of a structure is abbreviate | omitted.
[0022]
In the rack and pinion type steering apparatus of the embodiment, the seat 1 is prevented from falling off by the engagement between the convex portion 1 b of the seat 1 and the concave portion 96 b of the rack guide 96. Here, in the sheet 1, since the boundary between the convex portion 1b and the base portion 1a has a curvature radius R1 in the width direction, the bending stress in the width direction is not dispersed and concentrated on the boundary due to the shape effect. Moreover, in this sheet 1, since the boundary between the convex portion 1b and the base portion 1a has the curvature radius R2 in the longitudinal direction, the shear stress in the longitudinal direction is not dispersed and concentrated on the boundary due to the shape effect. For this reason, the sheet 1 exhibits high durability.
[0023]
Further, in this rack and pinion type steering device, the oil groove 1d of the seat 1 is separated from the throttle hole 1c, and therefore, as shown in FIG. Thickness T becomes thick and it is easy to ensure sufficient strength. For this reason, the sheet 1 can exhibit higher durability.
[0024]
Therefore, in this rack and pinion type steering apparatus, the seat 1 can exhibit high durability, and thus the safety and durability of the vehicle can be improved.
[0025]
In addition, the sheet | seat 1 characterized by embodiment is manufactured with the following metal mold | dies for a sheet | seat. As shown in FIG. 4, the sheet mold includes a first mold 2, a second mold 3 that can move up and down relatively with respect to the first mold 2, and a second mold 3. It consists of a slide pin 4 that can move up and down.
[0026]
A first main molding surface 2a that can be molded by bending the base portion 1a is recessed on the upper surface of the first mold 2, and a convex portion 1b can protrude from the base portion 1a at the center of the first main molding surface 2a. The first sub-molding surface 2b is recessed. The boundary between the first main molding surface 2a and the first sub molding surface 2b has a radius of curvature in the width direction (R1 is 0.5 (mm) or more, for example). The boundary between the first main molding surface 2a and the first sub molding surface 2b also has a radius of curvature in the longitudinal direction (R2 is 0.5 (mm) or less, for example, FIG. See B).
The curvature radius R1 in the width direction is larger than the curvature radius R2 in the longitudinal direction.
[0027]
Further, as shown in FIG. 4, a second main molding surface 3 a that can be molded by curving the base 1 a is provided on the lower surface of the second mold 3. A guide hole 3b penetrating vertically is formed in the second mold 3, and a cylindrical slide pin 4 is provided in the guide hole 3b so as to be movable up and down. The lower part of the slide pin 4 projects into the first sub-molding surface 2b of the first mold 2. On the second main molding surface 3 a of the second mold 3, an oil groove convex surface 3 c is provided so as to extend in the width direction and cross the first sub molding surface 2 b with the slide pin 4 interposed therebetween.
[0028]
When the sheet 1 is manufactured using the sheet mold configured as described above, first, the plate-shaped material W composed of the steel portion, the copper sintered portion, and the coating portion is placed on the first die 2. Then, the second mold 3 is lowered with respect to the first mold 2 and press working is performed. And when the 2nd type | mold 3 exists in a fall end position, the slide pin 4 is lowered | hung and a drawing process is performed.
[0029]
Thus, the base 1a of the material W is formed by the first main molding surface 2a and the second main molding surface 3a. At this time, the second main molding surface 3a has the oil groove 1d recessed in the base 1a by the oil groove convex surface 3c. Further, the material W has a convex portion 1 b formed by the first sub-molding surface 2 b and the lower portion of the slide pin 4.
[0030]
Although the embodiments of the present invention have been described above, it is added that the embodiments of the present invention have the following various technical matters in addition to the technical matters described in the claims. Keep it.
[0031]
(1) A pinion that is provided at the tip of the steering shaft and rotates with the steering shaft, and a rack bar that meshes with the pinion and converts the rotational motion of the steering shaft into a linear motion in the longitudinal direction to change the steering angle. A housing that accommodates the pinion and the rack bar and has a boss portion on the opposite side of the pinion across the rack bar, and an urging means that is movably provided in the axial direction within the boss portion of the housing. The rack bar is urged toward the pinion by the urging force of the rack, and the rack guide that guides the rack bar in the longitudinal direction is provided on the end surface of the rack guide on the rack bar side so as not to fall off. And a sheet for reducing sliding frictional force between the bar and the rack guide, and the rack guide has a recess at the center of the end surface on the rack bar side. The sheet protrudes from the base and has a convex part that engages with the concave part, and the boundary between the convex part and the base has a radius of curvature at least in the width direction perpendicular to the axial direction and the longitudinal direction. The mold for the seat in the rack and pinion type steering device,
[0032]
A first main molding surface that can be molded by curving the base is recessed, and a first sub-molding surface that can project the convex portion from the base is recessed at the center of the first main molding surface. A first mold in which a boundary between the first main molding surface and the first sub molding surface has a radius of curvature in the width direction;
[0033]
A second mold that is relatively close to the first mold, has a second main molding surface that can be molded by curving the base, and has a guide hole that penetrates in the proximity direction;
[0034]
A sheet metal mold comprising a cylindrical slide pin slidable in the guide hole of the second mold.
[0035]
(2) The first mold is characterized in that the boundary between the first main molding surface and the first sub-molding surface has a curvature radius in the longitudinal direction, and the curvature radius in the width direction is larger than the curvature radius in the longitudinal direction. Sheet metal mold described in Technical Item (1).
[0036]
(3) The second main molding surface of the second mold is provided with a convex surface for oil grooves that extends in the width direction and can intersect the first sub molding surface with the slide pin interposed therebetween. Technical matter (1) or (2) described above.
[Brief description of the drawings]
FIG. 1 is a plan view of a seat according to a rack and pinion type steering apparatus of an embodiment.
FIG. 2A is a cross-sectional view in the width direction of a seat according to the rack and pinion type steering apparatus of the embodiment, and FIG. 2B is an enlarged view of a main part of FIG.
3A is a partial cross-sectional view in the longitudinal direction of a seat according to the rack and pinion type steering apparatus of the embodiment, and FIG. 3B is an enlarged view of a main part of FIG.
FIG. 4 is a cross-sectional view of a sheet mold according to the rack and pinion type steering apparatus of the embodiment.
FIG. 5 is a schematic view of a rack and pinion type steering device.
FIG. 6 is a schematic diagram of a pinion and a rack bar.
FIG. 7 is a cross-sectional view in the width direction of the rack and pinion type steering device.
FIG. 8 is a plan view of a seat according to a conventional rack and pinion type steering apparatus.
9A is a sectional view in the width direction of a seat according to a conventional rack and pinion type steering apparatus, and FIG. 9B is an enlarged view of a main part of FIG. 9A.
FIG. 10 is a cross-sectional view in the width direction of a rack guide and a seat according to a conventional rack and pinion type steering device.
FIG. 11 is a cross-sectional view of a material constituting a seat according to a rack and pinion type steering apparatus.
[Explanation of symbols]
91 ... Steering shaft 92 ... Pinion 93 ... Rack bar 95 ... Housing 95a ... Boss part 96 ... Rack guide 1 ... Sheet 96b ... Concave part 1b ... Convex part 1a ... Base part 1d ... Oil groove

Claims (2)

A pinion that is provided at the tip of the steering shaft and rotates with the steering shaft; a rack bar that meshes with the pinion and changes the steering angle by converting the rotational motion of the steering shaft into a linear motion in the longitudinal direction; and the pinion And a housing having a boss portion on the opposite side of the pinion sandwiching the rack bar, and a biasing force of a biasing means provided so as to be movable in the axial direction within the boss portion of the housing The rack bar urges the rack bar toward the pinion side, and the rack bar guides the rack bar in the longitudinal direction, and is provided on the end surface of the rack guide on the rack bar side so as not to fall off. A sheet for reducing sliding friction with the rack guide, the rack guide having a recess at the center of the end surface on the rack bar side, Over metropolitan protrudes from the base portion, the rack-and-pinion type steering apparatus having a convex portion engaged with the concave portion,
Boundary between the convex portion and the base portion of the sheet is configured to have a radius of curvature in the width direction orthogonal to the previous SL-axis direction and the longitudinal direction, has a radius of curvature in the longitudinal direction, the width direction The rack and pinion type steering device is characterized in that the radius of curvature of the rack is larger than the radius of curvature in the longitudinal direction . The sliding surface of the seat with the rack bar is formed with an oil groove extending in the width direction and capable of intersecting with a portion corresponding to the convex portion, and the oil groove is separated from the portion. to claim 1 Symbol mounting rack and pinion type steering apparatus.

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