JP2016017565A - Bearing structure for supporting steering shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing structure for supporting a steering shaft, capable of stabilizing steering performance by suppressing excessive increase and decrease of an internal clearance of a bearing even when a temperature change occurs.SOLUTION: A bearing structure for supporting a steering shaft 3, including a ball bearing 6 rotatably supporting the steering shaft 3 rotated according to steering with respect to a housing, and having different linear expansion coefficients between the housing 54 and the ball bearing 6, further includes an annular sleeve 7 interposed between the housing 54 and the ball bearing 6, and having a linear expansion coefficient same as the linear expansion coefficient of the ball bearing 6. A male screw 71 formed on an outer periphery of a sleeve 7 and a female screw 54a formed on an inner periphery of the housing 54 are elastically deformed and screwed to each other.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a bearing structure that supports a steering shaft.

  For example, there is a bearing structure for supporting a steering shaft, in which a bearing disposed radially outside the steering shaft of the vehicle and interposed between the housing and the housing rotatably supports the steering shaft. This housing uses an aluminum alloy as a material for weight reduction. In an aluminum alloy housing and a steel bearing, the internal clearance in the radial direction of the bearing changes due to temperature change due to the difference in linear expansion coefficient. When the temperature is high, the internal clearance becomes excessive, and noise may be generated when the rolling elements of the bearing roll due to steering, which deteriorates the steering performance. On the other hand, when the temperature is low, the internal clearance becomes too small, and the raceway surface of the bearing becomes easy to peel off, which deteriorates the steering performance.

  Therefore, in order to improve these problems, even when there is a temperature change, a cylindrical sleeve made of steel is fitted on the bearing, and the clearance between the housing and the sleeve is managed more accurately. There is a bearing structure that supports a steering shaft, in which the internal clearance of the bearing is less likely to be excessive and excessive (see, for example, Patent Document 1).

JP 2012-255512 A

  However, in the bearing structure that supports the steering shaft described in Patent Document 1, the internal clearance of the bearing is less likely to become excessive and excessive when there is a temperature change, but the effect is small and still excessive and excessive. There was a case. And luxury cars, hybrid cars, and the like are required to be quiet, and it is necessary to prevent the generation of noise and suppress deterioration of steering performance even when there is a temperature change. Therefore, the bearing structure that supports the steering shaft has been required to suppress the internal clearance of the bearing from becoming too large or too small even when the temperature changes, and to stabilize the steering performance.

  The present invention has been made to solve such a problem, and even when there is a temperature change, the internal clearance of the bearing is prevented from becoming excessively large or small, and the steering performance can be stabilized. An object of the present invention is to provide a bearing structure that supports a steering shaft.

  In order to solve the above problems, a structural feature of a bearing structure for supporting a steering shaft according to claim 1 includes a bearing that rotatably supports a steering shaft that rotates in response to steering with respect to a housing. In the bearing structure for supporting the steering shaft having different configurations of the linear expansion coefficients of the housing and the bearing, the linear expansion coefficient is interposed between the housing and the bearing and is equivalent to the linear expansion coefficient of the bearing. A first screw portion formed on the outer periphery of the sleeve and a second screw portion formed on the inner periphery of the housing are elastically deformed and screwed together. is there.

  According to the bearing structure for supporting the steering shaft of the first aspect, the housing and the sleeve having different linear expansion coefficients are fixed by screwing the second screw portion of the housing and the first screw portion of the sleeve. In the elastic region where the second screw portion and the first screw portion are elastically deformed and screwed together, the clearance between the housing and the sleeve caused by the temperature change is caused by the difference in the linear expansion coefficient between the housing and the sleeve. Change can be absorbed. As a result, according to the bearing structure that supports the steering shaft, it is possible to suppress the internal clearance of the bearing from becoming excessive and small even when there is a temperature change, and to stabilize the steering performance.

  A structural feature of the bearing structure for supporting the steering shaft according to claim 2 is that the bearing and the sleeve are made of a steel material, and the housing is made of an aluminum alloy.

  According to the bearing structure for supporting the steering shaft according to the second aspect, the housing is made of an aluminum alloy having a larger linear expansion coefficient than that of the sleeve made of steel. In the elastic region where the second screw portion and the first screw portion are elastically deformed and screwed together, the clearance between the housing and the sleeve caused by the temperature change is caused by the difference in the linear expansion coefficient between the housing and the sleeve. Change can be absorbed. As a result, according to the bearing structure that supports the steering shaft, it is possible to suppress the internal clearance of the bearing from becoming excessive and small even when there is a temperature change, and to stabilize the steering performance.

  A structural feature of the bearing structure for supporting a steering shaft according to claim 3 is the bearing structure for supporting a steering shaft according to claim 1 or 2, wherein the sleeve has one end in the axial direction. An annular flange extending radially outward is formed, one side surface of the flange contacts the housing in the axial direction, meshes with a worm connected to an electric motor having a rotating shaft, and has an inner diameter side A worm wheel fixed to the steering shaft, wherein the sleeve and the worm wheel are disposed in a state where the other side surface of the heel and the side surface of the worm wheel are close to each other in the axial direction; That is, the side surface is subjected to low friction treatment.

  According to the bearing structure for supporting the steering shaft according to the third aspect, for example, when the vehicle wheel collides with the curb, the steering shaft and the worm wheel are rotated by the reaction force from the wheel. Even if the worm wheel rotates, the worm does not rotate because the inertia of the electric motor connected to the worm meshing with the worm wheel is large. Since the teeth of the worm wheel are inclined in the axial direction of the worm perpendicular to the axis of the worm wheel, if the worm wheel rotates without rotating the worm, the worm wheel moves in the axial direction. Then, the side surface of the worm wheel comes into contact with the other side surface of the adjacent kite. At this time, since one side surface of the heel is in contact with the housing, the movement of the worm wheel in the axial direction is restricted, and the other side surface of the heel is subjected to low friction processing, so that the worm wheel can be rotated. Does not have a big impact. As a result, the steering can be continued without greatly affecting the steering.

  According to the present invention, it is possible to provide a bearing structure that supports a steering shaft that can suppress the internal clearance of the bearing from becoming excessively large or small even when the temperature changes, and can stabilize the steering performance.

It is sectional drawing of the steering column apparatus which is one Embodiment of this invention. It is a principal part enlarged view of FIG.

  Hereinafter, an embodiment in which a bearing structure for supporting a steering shaft of the present invention is embodied in a steering column device 1 will be described with reference to the drawings. In the following description, the vehicle rear side indicates the right side in each drawing, and the vehicle front side indicates the left side in each drawing.

  FIG. 1 is a cross-sectional view of a steering column device 1 according to an embodiment of the present invention. As shown in FIG. 1, for example, a steering column device 1 mounted on a vehicle such as an automobile includes a steering shaft 3 (steering shaft) to which a steering wheel 2 is connected at one end, and a jacket that rotatably supports the steering shaft 3. 4 and an assist mechanism 5 that is disposed on the other end side of the steering shaft 3 and applies an operation assisting force for steering operation to the steering shaft 3.

  The steering shaft 3 is supported in the jacket 4 so as to be rotatable about its axis and contractible in the axial direction. A steering wheel 2 is fixed to one end of the steering shaft 3 on the vehicle rear side. On the other hand, an intermediate shaft (not shown) is connected to the other end of the steering shaft 3 on the front side of the vehicle via a universal joint (not shown), and rotation (steering torque) accompanying the steering operation is racked. The steering angle of a steered wheel (not shown) is changed by being transmitted to a steered mechanism (not shown) such as an & pinion mechanism.

  The jacket 4 has a double tube structure that contracts as the steering shaft 3 contracts. The jacket 4 is fixed to the vehicle body by fastening and fixing the upper bracket 11 fixed to the outer pipe to the vehicle body (not shown) with bolts (not shown).

  The assist mechanism 5 includes an electric motor 51, a worm 52 connected to the rotation shaft of the electric motor 51, and a worm wheel 53 that meshes with the worm 52 and is externally fitted to the steering shaft 3, and decelerates the power of the electric motor 51. And transmitted to the steering shaft 3. The assist mechanism 5 is housed in a housing 54 plastically processed with an aluminum alloy, and is fixed to the vehicle body by fastening and fixing the lower bracket 12 fixed to the housing 54 to the vehicle body with bolts (not shown).

  The steering shaft 3 is rotatably supported with respect to the housing 54 by disposing the ball bearing 13 on the vehicle rear side of the worm wheel 53 and the ball bearing 6 (bearing) on the vehicle front side. An annular sleeve 7 is interposed between the ball bearing 6 and the housing 54 on the outer diameter side.

  FIG. 2 is an enlarged view of a main part of FIG. As shown in FIG. 2, the ball bearing 6 includes an inner ring 61 that is externally fitted to the steering shaft 3 by an interference fit, an outer ring 62 that is disposed radially outward of the inner ring 61, and a plurality of rollers that roll between the inner and outer rings. A ball 63, a retainer 65 that holds the ball 63 in a rollable manner, and a pair of seals 64, 64 that seal the annular space between the inner and outer rings at both axial ends. As a material of the inner ring 61 and the outer ring 62, for example, a high carbon chrome bearing steel “SUJ2” is used, and the inner ring 61 and the outer ring 62 are made of a member having a smaller linear expansion coefficient than the housing 54. As a material of the steering shaft 3, for example, steel is used, and the linear expansion coefficient is substantially the same as that of the ball bearing 6.

  The steering shaft 3 is formed by expanding the diameter of the rear side of the vehicle via the step portion 31 from the portion where the inner ring 61 is fitted. A step portion 31 is in contact with the side surface of the inner ring 61 on the vehicle rear side in the axial direction. A retaining ring 15 attached to an annular groove 32 formed in the steering shaft 3 is in axial contact with the side surface of the inner ring 61 on the vehicle front side. As a result, the inner ring 61 is positioned in the axial direction.

  A cylindrical sleeve 7 is fitted on the outer periphery of the outer ring 62 by an interference fit. A male screw 71 (first screw portion) formed on the outer periphery of the sleeve 7 is screwed into a female screw 54 a (second screw portion) formed on the inner periphery of the housing 54. The male screw 71 and the female screw 54a are screwed together in an elastic region where these screws are elastically deformed. Thereby, the outer ring 62 is fixed to the housing 54 in the radial direction.

  The sleeve 7 is formed with an annular collar 72 extending radially outward from one axial end on the vehicle rear side. One side surface 73 on the vehicle front side of the collar 72 is in contact with the housing 54 in the axial direction.

  The sleeve 7 and the worm wheel 53 are arranged in a state where the other side surface 74 on the vehicle rear side of the collar 72 and the side surface 53a of the worm wheel 53 are close to each other in the axial direction. As a material of the sleeve 7, for example, a steel material such as a hot rolled mild steel plate “SPHC” is used, and the linear expansion coefficient is substantially the same as that of the ball bearing 6. The other side surface 74 of the collar 72 is subjected to a low friction treatment by, for example, fluorine coating.

Next, a procedure for assembling the ball bearing 6 and the sleeve 7 to the steering column device 1 will be described.
First, the sleeve 7 is press-fitted and fitted to the outer periphery of the ball bearing 6 shown in FIG. 2 to a predetermined position in the axial direction to obtain a first assembly. Next, the male screw 71 of the first assembly is screwed into the female screw 54a of the housing 54, and is screwed in until one side surface 73 of the flange 72 abuts the housing 54 in the axial direction, thereby fixing the first assembly to the housing 54. . Next, the steering shaft 3 is inserted into the ball bearing 6 fixed to the housing 54.

Next, the radial internal clearance of the ball bearing 6 due to a temperature change in the steering column apparatus 1 configured as described above will be described.
When the steering column device 1 is used in a high temperature state due to heat during vehicle travel, the steering shaft 3, the ball bearing 6 and the sleeve 7 use steel as materials and have substantially the same linear expansion coefficient. In these, the radial clearance does not change. In the sleeve 7 and the housing 54, since the linear expansion coefficient of the housing 54 is larger than that of the sleeve 7, the housing 54 expands more with respect to normal temperature. However, the sleeve 7 and the housing 54 can absorb a change caused by a difference in expansion in an elastic region where the male screw 71 and the female screw 54a are elastically deformed and screwed together. Thereby, the change of the internal clearance of the ball bearing 6 in the radial direction can be absorbed, and it is possible to suppress the internal clearance of the ball bearing 6 from being excessive even in a high temperature state and to stabilize the steering performance.

  On the other hand, when the steering column device 1 is used in a low temperature state, such as when the vehicle starts running in a cold region, the steering shaft 3, the ball bearing 6 and the sleeve 7 are made of steel as the material in the same way as in the high temperature state. In addition, since the linear expansion coefficients are substantially the same, the radial clearance does not change. In the sleeve 7 and the housing 54, since the linear expansion coefficient of the housing 54 is larger than that of the sleeve 7, the housing 54 contracts more greatly with respect to normal temperature. However, the sleeve 7 and the housing 54 can absorb changes resulting from differences in contraction in an elastic region where the male screw 71 and the female screw 54a are elastically deformed and screwed together. Thereby, the change of the internal clearance of the ball bearing 6 in the radial direction can be absorbed, the internal clearance of the ball bearing 6 can be suppressed from becoming too small even in a low temperature state, and the steering performance can be stabilized.

  As described above, according to the steering column device 1 according to the present embodiment that embodies the bearing structure that supports the steering shaft of the present invention, the internal clearance of the ball bearing 6 is excessively large and small even when there is a temperature change. Can be suppressed, and the steering performance can be stabilized.

  Further, according to the steering column device 1 according to the present embodiment, for example, when the vehicle wheel collides with the curb, the steering wheel 2 and the worm wheel 53 are rotated by the reaction force from the wheel. Even if the worm wheel 53 rotates, the worm 52 does not rotate because the inertia of the electric motor 51 connected to the worm 52 meshing with the worm wheel 53 is large. Since the teeth of the worm wheel 53 are inclined in the axial direction of the worm 52 perpendicular to the axis of the worm wheel 53, if the worm wheel 53 tries to rotate without the worm 52 rotating, the worm wheel 53 is pivoted. Will move in the direction. Then, the side surface 53a of the worm wheel 53 comes into contact with the other side surface 74 of the flange 72 adjacent thereto. At this time, since one side surface 73 of the collar 72 is in contact with the housing 54, the movement of the worm wheel 53 in the axial direction is restricted, and the other side surface 74 of the collar 72 is subjected to a low friction treatment. The rotation of the worm wheel 53 is not greatly affected. As a result, the steering can be continued without greatly affecting the steering.

  Further, according to the steering column apparatus 1 according to the present embodiment, the sleeve 7 and the ball bearing 6 have the same linear expansion coefficient, so that the ball bearing 6 and the sleeve 7 fixed to the outer periphery thereof are subject to temperature changes. Even if there is, the fixed state does not change. Since the sleeve 7 and the housing 54 absorb the change caused by the temperature change in the elastic region where the male screw 71 and the female screw 54a are elastically deformed and screwed together, the sleeve 7 and the housing 54 are fixed. Yes. Thereby, since the ball bearing 6 is being fixed to the housing 54 via the sleeve 7, it has controlled that the ball bearing 6 moves to an axial direction, ie, the ball bearing 6 can be prevented from coming off.

  In addition, this invention is not limited to this embodiment, In the range which does not deviate from the summary of this invention, it can implement with a various form.

1: Steering column device, 2: Steering wheel, 3: Steering shaft (steering shaft), 4: Jacket, 5: Assist mechanism, 6: Ball bearing (bearing), 7: Sleeve, 11: Upper bracket, 12: Lower bracket , 13: ball bearing, 15: retaining ring, 31: stepped portion, 32: annular groove, 51: electric motor, 52: worm, 53: worm wheel, 53a: side surface, 54: housing, 54a: female screw (second screw) Part), 54b: side face, 61: inner ring, 62: outer ring, 63: ball, 64: seal, 65: retainer, 71: male screw (first screw part), 72: hook, 73: one side, 74: The other side

Claims (3)

In a bearing structure for supporting the steering shaft, comprising a bearing that rotatably supports a steering shaft that rotates in response to steering, the linear expansion coefficient of the housing and the bearing being different from each other.
An annular sleeve interposed between the housing and the bearing and having a linear expansion coefficient equivalent to the linear expansion coefficient of the bearing;
A bearing for supporting a steering shaft, wherein a first screw portion formed on an outer periphery of the sleeve and a second screw portion formed on an inner periphery of the housing are elastically deformed and screwed together. Construction.   2. The bearing structure for supporting a steering shaft according to claim 1, wherein the bearing and the sleeve are made of a steel material, and the housing is made of an aluminum alloy. 3. The bearing structure for supporting a steering shaft according to claim 1 or 2, wherein the sleeve is formed with an annular collar extending radially outward from one axial end, and one of the collars. Side surface of the housing abuts the housing in the axial direction,
A worm wheel meshed with a worm connected to an electric motor having a rotating shaft and having an inner diameter side fixed to the steering shaft;
The sleeve and the worm wheel are arranged in a state where the other side surface of the heel and the side surface of the worm wheel are close to each other in the axial direction, and the other side surface of the heel is subjected to a low friction treatment. Bearing structure that supports the steering shaft.

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