JP2019006364A - Steering device and intermediary shaft - Google Patents

Abstract

To provide a steering device absorbing an impact with an intermediary shaft which can be easily manufactured and enables deformation properties thereof to be easily changed.SOLUTION: A steering device comprises: a first universal joint; a second universal joint which is arranged anterior to the first universal joint; and an intermediary shaft which connects the first universal joint to the second universal joint. The intermediary shaft has: a first shaft which is a solid member; and a cylindrical second shaft which is detachably connected to the first shaft. The first shaft has an impact absorption section provided with grooves on an outer periphery thereof.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a steering device and an intermediate shaft.

  A vehicle is provided with a steering device as a device for transmitting an operation of an operator (driver) to a steering wheel to the wheel. A steering device that makes it difficult to transmit an impact to a steering wheel when a vehicle collision occurs is known. For example, Patent Document 1 describes an intermediate shaft including a tubular bellows. According to Patent Document 1, the impact is absorbed by the deformation of the bellows during the primary collision.

JP 2005-145164 A

  However, a special and expensive facility is required for producing the tubular bellows. Furthermore, in order to change the deformation characteristics of the bellows according to the shock absorbing performance required individually, it is necessary to change the mold. For this reason, there has been a demand for an intermediate shaft that can be easily manufactured and whose deformation characteristics can be easily changed.

  The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a steering device that absorbs an impact by an intermediate shaft that can be easily manufactured and can easily change deformation characteristics.

  In order to achieve the above object, a steering device according to an aspect of the present disclosure includes a first universal joint, a second universal joint disposed in front of the first universal joint, the first universal joint, An intermediate shaft that connects the second universal joint, and the intermediate shaft includes a first shaft that is a solid member, and a cylindrical second shaft that is detachably connected to the first shaft. The first shaft includes an impact absorbing portion having a groove on the outer peripheral surface.

  Thereby, since a metal mold is not required for forming the first shock absorbing portion, the first shock absorbing portion can be easily formed. Further, the deformation characteristics of the first shock absorber change depending on the shape of the groove of the first shock absorber. Since it is easy to change the shape of the groove, it is easy to adjust the deformation characteristics of the first shock absorber. Therefore, the steering device can absorb the impact by the intermediate shaft that can be easily manufactured and can easily change the deformation characteristics.

  Furthermore, the second shaft moves relative to the first shaft during the primary collision. The steering device can absorb an impact by friction generated between the first shaft and the second shaft.

  As a desirable aspect of the steering apparatus, the first shaft includes a first fitting portion having serrations on an outer peripheral surface, and the second shaft includes a second fitting portion having serrations on an inner peripheral surface, One fitting part fits into the second fitting part, and the maximum diameter of the shock absorbing part is smaller than the minimum diameter of the first fitting part.

  Thereby, when the 2nd shaft moves relatively with respect to the 1st shaft, it becomes difficult to interfere with the serration of the 1st shock absorption part and the 2nd fitting part. For this reason, the steering device can suppress variations in the impact absorbing ability of the intermediate shaft.

  As a desirable mode of the steering device, the impact absorbing portion includes a plurality of the grooves, and the grooves are annular.

  Thereby, when bending stress acts on the intermediate shaft, stress concentration occurs in a plurality of portions of the first shock absorbing portion. For this reason, since the range of the part which the 1st impact-absorbing part deform | transforms tends to become large, the impact-absorbing capability of an intermediate shaft improves. Furthermore, since the groove is annular, the direction in which the intermediate shaft bends is difficult to be limited.

  As a desirable mode of the steering device, the groove is spiral.

  Thereby, when bending stress acts on the intermediate shaft, stress concentration occurs in a plurality of portions of the first shock absorbing portion. For this reason, since the deformation of the first shock absorbing portion tends to be large, the shock absorbing ability of the intermediate shaft is improved. Furthermore, since the groove is spiral, the direction in which the intermediate shaft bends is difficult to be limited.

  As a desirable aspect of the steering device, the maximum width of the groove is 1 mm or more and 3 mm or less, and the surface of the shock absorbing portion facing the groove is cut in a cross section obtained by cutting the intermediate shaft in a plane perpendicular to the radial direction. At least a part draws an arc having a radius of curvature of 0.2 mm to 1.0 mm.

  Thereby, extreme stress concentration does not occur in the first shock absorbing part, and the first shock absorbing part is easily bent.

  As a desirable mode of the steering device, the width of the groove is reduced toward the bottom of the groove.

  Thereby, when bending stress acts on the intermediate shaft, stress concentration is likely to occur.

  As a desirable mode of the steering device, a covering material covering at least a part of the surface of the impact absorbing portion facing the groove is provided, and the covering material is a rust preventive film.

  The shock absorber is designed to transmit a predetermined torque. In the shock absorbing part having a groove, the strength against the torque of the part corresponding to the groove is low. Although the impact absorbing portion is designed in consideration of a sufficient safety factor, if the impact absorbing portion rusts, the impact absorbing portion may not be able to withstand a predetermined torque. On the other hand, in the impact absorbing portion, the occurrence of rust on the surface facing the groove is suppressed by the covering material. The strength reduction of the portion corresponding to the groove of the shock absorbing portion is suppressed.

  As a desirable mode of the steering device, the covering material covers a main surface which is a surface outside the groove of the shock absorbing portion.

  When a predetermined axial load is applied to the intermediate shaft, the first shaft and the second shaft move relatively. If a bending moment is also applied to the intermediate shaft, the second shaft may be caught by the impact absorbing portion. On the other hand, the friction between the second shaft and the impact absorbing portion is reduced by covering the main surface with the covering material. For this reason, even if the second shaft comes into contact with the shock absorber, the second shaft is not easily caught by the shock absorber. For this reason, the movement of the second shaft becomes smooth.

  As a desirable mode of the steering device, a filler disposed in the groove is provided.

  In the shock absorbing part, it is difficult for water to enter the groove by the filler. For this reason, generation | occurrence | production of the rust on the surface of the shock absorption part which faces a groove | channel is suppressed. The strength reduction of the portion corresponding to the groove of the shock absorbing portion is suppressed.

  As a desirable mode of a steering device, the filler is resin. Thereby, it becomes difficult for a filler to inhibit a deformation | transformation of an impact absorption part.

  As a desirable mode of the steering device, the filler is rubber. Thereby, it becomes difficult for a filler to inhibit a deformation | transformation of an impact absorption part.

  As a desirable mode of the steering device, the filler is a closed cell body. Thereby, the increase in the weight of an impact-absorbing part is suppressed.

  An intermediate shaft according to an aspect of the present disclosure is an intermediate shaft used in a steering device, and includes a first shaft that is a solid member, and a cylindrical second shaft that is detachably connected to the first shaft. The first shaft includes an impact absorbing portion having a groove on the outer peripheral surface.

  Thereby, since a metal mold is not required for forming the first shock absorbing portion, the first shock absorbing portion can be easily formed. Further, the deformation characteristics of the first shock absorber change depending on the shape of the groove of the first shock absorber. Since it is easy to change the shape of the groove, it is easy to adjust the deformation characteristics of the first shock absorber. Therefore, the intermediate shaft can be easily manufactured and the deformation characteristics can be easily changed.

  Furthermore, the second shaft moves relative to the first shaft during the primary collision. The intermediate shaft can absorb an impact by friction generated between the first shaft and the second shaft.

  According to the present disclosure, it is possible to provide a steering device that absorbs an impact by an intermediate shaft that can be easily manufactured and easily change deformation characteristics.

FIG. 1 is a schematic diagram of a steering apparatus according to the present embodiment. FIG. 2 is a perspective view of the steering apparatus of the present embodiment. FIG. 3 is a perspective view of the intermediate shaft of the present embodiment. FIG. 4 is a cross-sectional view of the intermediate shaft of the present embodiment. FIG. 5 is an enlarged cross-sectional view of the first shock absorbing portion and the first fitting portion of the first shaft. FIG. 6 is an enlarged cross-sectional view of the peripheral portion of the groove of the first shock absorber. FIG. 7 is an enlarged cross-sectional view of the second shock absorbing portion of the first shaft. 8 is a cross-sectional view taken along line AA in FIG. 9 is a cross-sectional view taken along the line BB in FIG. FIG. 10 is a perspective view of the intermediate shaft after the second shaft has entered the first shaft. FIG. 11 is a perspective view of the intermediate shaft after the first shaft is bent. FIG. 12 is a side view of the first shock absorber in the intermediate shaft of the first modification. FIG. 13 is an enlarged view of the peripheral portion of the groove in the intermediate shaft of the second modified example. FIG. 14 is an enlarged cross-sectional view of the periphery of the groove of the first shock absorber in the third modification. FIG. 15 is an enlarged cross-sectional view of the first shock absorber in the fourth modification. FIG. 16 is a cross-sectional view of an intermediate shaft of a fifth modification.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the following modes for carrying out the invention (hereinafter referred to as embodiments). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. Furthermore, the constituent elements disclosed in the following embodiments can be appropriately combined.

(Embodiment)
FIG. 1 is a schematic diagram of a steering apparatus according to the present embodiment. FIG. 2 is a perspective view of the steering apparatus of the present embodiment. As shown in FIG. 1, the steering device 80 includes a steering wheel 81, a steering shaft 82, a steering force assist mechanism 83, a first universal joint 84, and an intermediate shaft 85 in the order in which the force given by the operator is transmitted. And a second universal joint 86, which are joined to the pinion shaft 87. In the following description, the front in the vehicle on which the steering device 80 is mounted is simply described as the front, and the rear in the vehicle is simply described as the rear.

  As shown in FIG. 1, the steering shaft 82 includes an input shaft 82a and an output shaft 82b. One end of the input shaft 82a is connected to the steering wheel 81, and the other end of the input shaft 82a is connected to the output shaft 82b. One end of the output shaft 82 b is connected to the input shaft 82 a, and the other end of the output shaft 82 b is connected to the first universal joint 84.

  As shown in FIG. 1, the intermediate shaft 85 connects the first universal joint 84 and the second universal joint 86. One end of the intermediate shaft 85 is connected to the first universal joint 84 and the other end is connected to the second universal joint 86. One end of the pinion shaft 87 is connected to the second universal joint 86, and the other end of the pinion shaft 87 is connected to the steering gear 88. The first universal joint 84 and the second universal joint 86 are, for example, cardan joints. The rotation of the steering shaft 82 is transmitted to the pinion shaft 87 via the intermediate shaft 85. That is, the intermediate shaft 85 rotates with the steering shaft 82.

  As shown in FIG. 1, the steering gear 88 includes a pinion 88a and a rack 88b. The pinion 88a is connected to the pinion shaft 87. The rack 88b meshes with the pinion 88a. The steering gear 88 converts the rotational motion transmitted to the pinion 88a into a linear motion by the rack 88b. The rack 88 b is connected to the tie rod 89. The angle of the wheels changes as the rack 88b moves.

  As shown in FIG. 1, the steering force assist mechanism 83 includes a speed reducer 92 and an electric motor 93. The speed reducer 92 is, for example, a worm speed reducer. Torque generated by the electric motor 93 is transmitted to the worm wheel via the worm inside the speed reducer 92 and rotates the worm wheel. The reduction gear 92 increases the torque generated by the electric motor 93 by the worm and the worm wheel. The speed reducer 92 gives auxiliary steering torque to the output shaft 82b. That is, the steering device 80 is a column assist system.

  As shown in FIG. 1, the steering device 80 includes an ECU (Electronic Control Unit) 90, a torque sensor 94, and a vehicle speed sensor 95. The electric motor 93, the torque sensor 94, and the vehicle speed sensor 95 are electrically connected to the ECU 90. The torque sensor 94 outputs the steering torque transmitted to the input shaft 82a to the ECU 90 by CAN (Controller Area Network) communication. The vehicle speed sensor 95 detects the traveling speed (vehicle speed) of the vehicle body on which the steering device 80 is mounted. The vehicle speed sensor 95 is provided in the vehicle body and outputs the vehicle speed to the ECU 90 by CAN communication.

  The ECU 90 controls the operation of the electric motor 93. The ECU 90 acquires signals from each of the torque sensor 94 and the vehicle speed sensor 95. The ECU 90 is supplied with electric power from a power supply device 99 (for example, an in-vehicle battery) with the ignition switch 98 being on. The ECU 90 calculates an auxiliary steering command value based on the steering torque and the vehicle speed. The ECU 90 adjusts the power value supplied to the electric motor 93 based on the auxiliary steering command value. The ECU 90 acquires information on the induced voltage from the electric motor 93 or information output from a resolver or the like provided in the electric motor 93. As the ECU 90 controls the electric motor 93, the force required to operate the steering wheel 81 is reduced.

  FIG. 3 is a perspective view of the intermediate shaft of the present embodiment. FIG. 4 is a cross-sectional view of the intermediate shaft of the present embodiment. FIG. 5 is an enlarged cross-sectional view of the first shock absorbing portion and the first fitting portion of the first shaft. FIG. 6 is an enlarged cross-sectional view of the peripheral portion of the groove of the first shock absorber. FIG. 7 is an enlarged cross-sectional view of the second shock absorbing portion of the first shaft. 8 is a cross-sectional view taken along line AA in FIG. 9 is a cross-sectional view taken along the line BB in FIG.

  As shown in FIG. 3, the intermediate shaft 85 includes a first shaft 1 and a second shaft 2.

  The first shaft 1 is a substantially cylindrical solid member. For example, the 1st shaft 1 is formed by S35C which is carbon steel for machine structures (SC material (Carbon Steel for Machine Structural Use)). As shown in FIG. 4, the first shaft 1 includes a base portion 11, a second impact absorbing portion 12, a base portion 13, a first impact absorbing portion 15, and a first fitting portion 17.

  The base 11 is fixed to the first universal joint 84. The diameter of the base 11 is constant. The second shock absorber 12 is located in front of the base 11. The second shock absorber 12 is located on the rear side of the center of the first shaft 1 in the axial direction of the first shaft 1. The base 13 is located in front of the second shock absorber 12. The diameter of the base 13 is constant and is equal to the diameter of the base 11. The first shock absorber 15 is located in front of the base 13. The first shock absorber 15 is located at the center of the first shaft 1 in the axial direction of the first shaft 1. The first fitting portion 17 is located at the front end portion of the first shaft 1. The first fitting portion 17 includes a serration 17a on the outer peripheral surface. Moreover, the 1st fitting part 17 has the recessed part 170 in the end surface of the front side, as shown in FIG.

  In the following description, the axial direction of the first shaft 1 is simply described as the axial direction, and the direction orthogonal to the axial direction is described as the radial direction. 4 to 7 are cross sections in which the first shaft 1 is cut along a plane perpendicular to the radial direction.

  As shown in FIG. 5, the first shock absorber 15 includes a plurality of grooves 3 and a plurality of convex portions 4. The groove 3 is annular. The groove 3 is formed by cutting, for example. The plurality of grooves 3 are arranged at equal intervals in the axial direction. The convex part 4 is located between the two grooves 3. The diameter D1 of the first shock absorber 15 at the position corresponding to the convex portion 4 is equal to the diameters of the base 11 and the base 13. The diameter D1 is smaller than the minimum diameter D4 of the first fitting portion 17. The minimum diameter D4 is the diameter of the first fitting portion 17 at a position corresponding to the valley of the serration 17a.

  As shown in FIG. 6, the first shock absorber 15 has a first side surface 31, a second side surface 33, a bottom surface 35, a first connection surface 36, and a second connection surface as surfaces facing the groove 3. 37. The first side surface 31 and the second side surface 33 are perpendicular to the axial direction. That is, the second side surface 33 is parallel to the first side surface 31. The bottom surface 35 is located between the first side surface 31 and the second side surface 33. The first side surface 31 is located rearward with respect to the bottom surface 35, and the second side surface 33 is located forward with respect to the bottom surface 35. The bottom surface 35 is a curved surface. The first connection surface 36 is a curved surface that connects the first side surface 31 and the bottom surface 35. The second connection surface 37 is a curved surface that connects the second side surface 33 and the bottom surface 35.

  The maximum width W of the groove 3 is preferably 1 mm or more and 3 mm or less. In the cross section shown in FIG. 6, the first connection surface 36 and the second connection surface 37 draw the same arc (hereinafter referred to as the first arc). The curvature radius C1 of the first arc is preferably 0.2 mm or greater and 1.0 mm or less. For example, the curvature radius C1 in this embodiment is 0.3 mm.

  The first shock absorber 15 is designed to transmit a torque of, for example, 300 Nm. When the 1st shaft 1 is formed by S35C, the diameter D2 of the 1st shock absorption part 15 in the position corresponding to the bottom of the groove | channel 3 will be about 14 mm or more and 16 mm or less. The diameter D2 is determined by the depth H of the groove 3 shown in FIG.

  As shown in FIG. 7, the second shock absorber 12 includes a small diameter portion 125, a first connection portion 121, and a second connection portion 129. The small diameter part 125 is cylindrical. The diameter D3 of the small diameter portion 125 is smaller than the diameter D2 shown in FIG. The axial length L of the small diameter portion 125 is larger than the maximum width W of the groove 3. The first connection part 121 connects the base part 11 and the small diameter part 125. The second connection portion 129 connects the base portion 13 and the small diameter portion 125. In the cross section shown in FIG. 7, the surfaces of the first connection part 121 and the second connection part 129 draw the same arc (hereinafter referred to as a second arc). The radius of curvature C2 of the second arc is larger than the radius of curvature C1 of the first arc. The curvature radius C2 is preferably 5 mm or more. For example, the curvature radius C2 is 8 mm.

  The second shock absorber 12 is designed to be deformed with a torque of about 150 Nm to 250 Nm, for example. When the intermediate shaft 85 is formed of S35C, the diameter D3 is about 13 mm or more and 15.5 mm or less. For example, in the present embodiment, the diameter D3 is 13 mm.

  As shown in FIG. 4, the 2nd shaft 2 is cylindrical. For example, the second shaft 2 is formed of a carbon steel pipe for machine structure (STKM material (Carbon Steel Tubes for Machine Structural Purposes)). The second shaft 2 includes a second fitting part 21, a large diameter part 23, and a base part 25.

  The second fitting portion 21 is disposed at the rear end portion of the second shaft 2. The first fitting portion 17 is inserted into the second fitting portion 21. The second fitting portion 21 includes a serration 21a on the inner peripheral surface. The serration 21a meshes with the serration 17a.

  As shown in FIG. 8, the outer shape of the first fitting portion 17 draws a circle in a cross section orthogonal to the axial direction. In the cross section shown in FIG. 8, the outer shape of the second fitting portion 21 draws an ellipse. As shown in FIG. 9, the outer shape of the first fitting portion 17 draws an ellipse in a cross section different from FIG. 8 among the cross sections orthogonal to the axial direction. In the cross section shown in FIG. 9, the external shape of the 2nd fitting part 21 draws a circle. In addition, the shape of the 2nd fitting part 21 of FIG. 8 and the 1st fitting part 17 of FIG. 9 is exaggerated for description, and is different from an actual shape. In practice, all teeth of serration 21a are each located between two teeth of serration 17a. That is, the teeth of the serration 21a located on the left and right sides in FIG. 8 are not in contact with the teeth of the serration 17a, but are located between the two teeth of the serration 17a. The teeth of the serration 21a located on the upper side and the lower side in FIG. 9 are not in contact with the teeth of the serration 17a, but are located between the two teeth of the serration 17a.

  When the intermediate shaft 85 is assembled, a part of the first fitting portion 17 is inserted into the second fitting portion 21. And the 1st fitting part 17 and the 2nd fitting part 21 are pressed from two directions in the position corresponding to the recessed part 170. FIG. Thereafter, the first fitting portion 17 is further pushed into the second fitting portion 21. Thereby, the cross-sectional shape shown in FIGS. 8 and 9 is formed. In addition, such a connection method of the 1st fitting part 17 and the 2nd fitting part 21 may be called ellipse fitting.

  The movement of the second fitting portion 21 relative to the first fitting portion 17 is restricted by the friction generated at the contact portion between the first fitting portion 17 and the second fitting portion 21. That is, the second fitting portion 21 does not move relative to the first fitting portion 17 during normal use (when no collision occurs). On the other hand, when a predetermined axial load is applied to the second shaft 2 during a collision, the second fitting portion 21 moves relative to the first fitting portion 17. The predetermined load is, for example, about 1 kN to 3 kN. That is, the second shaft 2 is connected to the first shaft 1 so that it can be detached from the first shaft 1 in the event of a collision. The impact is absorbed by the friction between the second fitting portion 21 and the first fitting portion 17.

  The large diameter portion 23 is disposed in front of the second fitting portion 21. The outer diameter of the large diameter portion 23 is constant. The outer diameter of the large diameter portion 23 is larger than the outer diameter of the second fitting portion 21.

  The base portion 25 is disposed at the front end portion of the second shaft 2. The base portion 25 is fixed to the second universal joint 86. The outer diameter of the base 25 is constant. The outer diameter of the base portion 25 is equal to the outer diameter of the second fitting portion 21.

  FIG. 10 is a perspective view of the intermediate shaft after the second shaft has entered the first shaft. FIG. 11 is a perspective view of the intermediate shaft after the first shaft is bent.

  When the vehicle collides, a load is applied to the steering gear 88. The load applied to the steering gear 88 is transmitted to the second shaft 2 via the second universal joint 86. When the entire front surface of the vehicle hits the collision object (in the case of a full lap collision), an axial load is often applied to the second shaft 2. In the case of a full wrap collision, the impact is absorbed by the movement of the second shaft 2 relative to the first shaft 1 as shown in FIG. As a result, the impact transmitted to the steering wheel 81 is reduced.

  On the other hand, when a part of the front surface of the vehicle hits a collision object (in the case of an offset collision), a load that is not in the axial direction is often applied to the second shaft 2. For this reason, the second shaft 2 cannot move straight with respect to the first shaft 1. In the case of an offset collision, bending stress is generated on the intermediate shaft 85. At this time, stress concentration occurs in the first connection surface 36 and the second connection surface 37, so that the first shock absorbing portion 15 bends from the first connection surface 36 and the second connection surface 37 as shown in FIG. . One side in the radial direction of the groove 3 expands, and the other side in the radial direction of the groove 3 contracts. On the side where the groove 3 shrinks, the convex portion 4 is in contact with the adjacent convex portion 4. The bent intermediate shaft 85 enters a gap between peripheral parts of the intermediate shaft 85. When the first shock absorber 15 is bent, the shock due to the collision is absorbed. As a result, the impact transmitted to the steering wheel 81 is reduced.

  Since the first shock absorber 15 includes the plurality of grooves 3, when bending stress acts on the intermediate shaft 85, stress concentration occurs at a plurality of portions of the first shock absorber 15. For this reason, since the range of the part which the 1st impact-absorbing part 15 deform | transforms tends to become large, the impact-absorbing capability of the intermediate shaft 85 improves.

  A bending stress due to a primary collision may occur in the intermediate shaft 85, and a large torque (torsional force) may be input when the vehicle rides on the curb. For this reason, the intermediate shaft 85 is required to be able to suppress damage when receiving a large torque and to absorb an impact at the time of a primary collision.

  In the intermediate shaft 85 of the present embodiment, the diameter D3 is smaller than the diameter D2. For this reason, the second impact absorbing portion 12 is deformed (twisted) when the vehicle rides on the curb. The energy input to the intermediate shaft 85 is absorbed by the deformation of the second shock absorber 12. Since energy is absorbed by the second shock absorber 12, deformation of the first shock absorber 15 is suppressed.

  On the other hand, in the intermediate shaft 85 of the present embodiment, the curvature radius C2 is larger than the curvature radius C1. For this reason, when a bending stress is generated in the intermediate shaft 85 at the time of the primary collision, not the second shock absorber 12 but the first shock absorber 15 is deformed (bent).

  In addition, the groove | channel 3 of the 1st shock absorption part 15 does not necessarily need to have the shape mentioned above. For example, the first connection surface 36 and the second connection surface 37 may be connected without passing through the bottom surface 35. That is, in the cross section obtained by cutting the intermediate shaft 85 along a plane perpendicular to the radial direction, the surface of the first shock absorber 15 at a position corresponding to the bottom of the groove 3 may draw a semicircle. Further, the first connection surface 36 and the second connection surface 37 may not be provided. That is, the first side surface 31 and the second side surface 33 may be directly connected to the bottom surface 35.

  Note that the number of grooves 3 provided in the first shock absorber 15 is not necessarily the number shown in the figure. The first shock absorber 15 only needs to have at least one groove 3.

  Note that the diameter D1 of the first shock absorbing portion 15 at the position corresponding to the convex portion 4 does not necessarily have to be equal to the diameter of the base portion 11. The diameter D <b> 1 only needs to be larger than the diameter D <b> 2 of the first shock absorber 15 at a position corresponding to the bottom of the groove 3 and smaller than the minimum diameter D <b> 4 of the first fitting portion 17. The diameter D1 may be smaller than the diameter of the base 11 or may be larger than the diameter of the base 11.

  In addition, the connection method using the resin coat slider or the connection method using a rolling element may be sufficient as the connection method of the 1st fitting part 17 and the 2nd fitting part 21. FIG. The connection method using the resin coat slider is a method of fitting the first fitting portion 17 having the lubricating film to the second fitting portion 21. The lubricant film is formed, for example, by applying grease on the outer peripheral surface of the first fitting portion 17 and then applying a grease. Thereby, wear of a contact portion between the first fitting portion 17 and the second fitting portion 21 is reduced, and frictional resistance is reduced. The lubricating film may be provided on the second fitting portion 21 or may be provided on both the first fitting portion 17 and the second fitting portion 21. Moreover, the connection method using a rolling element is a method of connecting the 1st fitting part 17 and the 2nd fitting part 21 via a rolling element. Examples of rolling elements include balls or rollers. A ball and a roller may be combined as a rolling element. Thereby, wear of a contact portion between the first fitting portion 17 and the second fitting portion 21 is reduced, and frictional resistance is reduced.

  As described above, the steering device 80 includes the first universal joint 84, the second universal joint 86 disposed on the front side of the first universal joint 84, the first universal joint 84, and the second universal joint 86. And an intermediate shaft 85 connecting the two. The intermediate shaft 85 includes a first shaft 1 that is a solid member, and a cylindrical second shaft 2 that is detachably coupled to the first shaft 1. The first shaft 1 includes a first shock absorber 15 having a groove 3 on the outer peripheral surface.

  Thereby, since a metal mold is not required for forming the first shock absorbing portion 15, the first shock absorbing portion 15 can be easily formed. Further, the deformation characteristics of the first shock absorber 15 change according to the shape of the groove 3 of the first shock absorber 15. Since it is easy to change the shape of the groove 3, it is easy to adjust the deformation characteristics of the first shock absorber 15. Therefore, the steering device 80 can absorb the impact by the intermediate shaft 85 that can be easily manufactured and can easily change the deformation characteristics.

  Furthermore, the second shaft 2 moves relative to the first shaft 1 at the time of the primary collision. The steering device 80 can absorb an impact by friction generated between the first shaft 1 and the second shaft 2.

  Moreover, the 1st shaft 1 is provided with the 1st fitting part 17 which has the serration 17a in an outer peripheral surface. The second shaft 2 includes a second fitting portion 21 having a serration 21a on the inner peripheral surface. The first fitting portion 17 is fitted into the second fitting portion 21. The maximum outer diameter (diameter D1) of the first shock absorbing portion 15 is smaller than the minimum diameter D4 of the first fitting portion 17.

  Thereby, when the 2nd shaft 2 moves relatively with respect to the 1st shaft 1, the 1st shock absorption part 15 and the serration 21a of the 2nd fitting part 21 become difficult to interfere. For this reason, the steering device 80 can suppress variations in the impact absorbing ability of the intermediate shaft 85.

  In the steering device 80, the first shock absorber 15 includes a plurality of grooves 3. The groove 3 is annular.

  As a result, when bending stress acts on the intermediate shaft 85, stress concentration occurs at a plurality of portions of the first shock absorbing portion 15. For this reason, since the range of the part which the 1st impact-absorbing part 15 deform | transforms tends to become large, the impact-absorbing capability of the intermediate shaft 85 improves. Furthermore, since the groove 3 is annular, the direction in which the intermediate shaft 85 bends is difficult to be limited.

  In the steering device 80, the maximum width W of the groove 3 is not less than 1 mm and not more than 3 mm. In a cross section obtained by cutting the intermediate shaft 85 in a plane perpendicular to the radial direction, at least a part of the surface of the first shock absorber 15 facing the groove 3 has a radius of curvature of 0.2 mm to 1.0 mm. Draw an arc.

  Thereby, extreme stress concentration does not occur in the first shock absorber 15 and the first shock absorber 15 is easily bent.

(First modification)
FIG. 12 is a side view of the first shock absorber in the intermediate shaft of the first modification. Note that the same components as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 12, the first shock absorber 15A of the first modification includes a groove 3A. The groove 3A has a spiral shape. The above description of the maximum width W and the radius of curvature C1 of the groove 3 can be applied to the groove 3A.

  Thereby, when a bending stress acts on the intermediate shaft 85, stress concentration occurs in a plurality of portions of the first shock absorbing portion 15A. For this reason, since the deformation of the first shock absorbing portion 15A tends to be large, the shock absorbing ability of the intermediate shaft 85 is improved. Furthermore, since the groove 3A is spiral, the direction in which the intermediate shaft 85 bends is not easily limited.

(Second modification)
FIG. 13 is an enlarged view of the peripheral portion of the groove in the intermediate shaft of the second modified example. Note that the same components as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

  The first shock absorber 15B of the second modification includes a plurality of grooves 3B. As shown in FIG. 13, the first shock absorber 15B has a first side surface 31B, a second side surface 33B, a bottom surface 35B, a first connection surface 36B, and a second connection surface as surfaces facing the groove 3B. 37B. The bottom surface 35B is located between the first side surface 31B and the second side surface 33B. The first connection surface 36B is a curved surface that connects the first side surface 31B and the bottom surface 35B. The second connection surface 37B is a curved surface that connects the second side surface 33B and the bottom surface 35B. The distance between the first side surface 31B and the second side surface 33B decreases toward the bottom surface 35B. That is, the width of the groove 3B decreases toward the bottom of the groove 3B.

  Thereby, when a bending stress is applied to the intermediate shaft 85, stress concentration is likely to occur.

(Third Modification)
FIG. 14 is an enlarged cross-sectional view of the periphery of the groove of the first shock absorber in the third modification. Note that the same components as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 14, in the third modification, the covering material 5 is provided on the first shock absorber 15 </ b> C. The covering material 5 covers the surfaces (the first side surface 31, the second side surface 33, the bottom surface 35, the first connection surface 36, and the second connection surface 37) facing the groove 3 of the first shock absorber 15C. That is, the covering material 5 covers the inner peripheral surface of the groove 3. Moreover, the coating | covering material 5 covers the main surface 150 which is a surface outside the groove | channel 3 of 15 C of 1st shock absorption parts. That is, in the third modification, the covering material 5 covers the entire surface of the first shock absorbing portion 15C. The covering material 5 is a rust preventive film. The covering material 5 contains, for example, zinc or nickel. In other words, the surface of the first shock absorber 15C is galvanized or nickel plated.

  The covering material 5 does not necessarily have to cover the entire surface of the first shock absorbing portion 15C. The covering material 5 only needs to cover at least a part of the surface facing the groove 3 of the first shock absorbing portion 15C. The covering material 5 preferably covers at least the bottom surface 35, the first connection surface 36, and the second connection surface 37. The covering material 5 may be grease, for example. In this case, the viscosity of the grease is preferably higher.

  As described above, the steering device 80 according to the third modification includes the covering material 5 that covers at least a part of the surface of the first shock absorber 15C facing the groove 3. The covering material 5 is a rust preventive film.

  The first shock absorber 15C is designed to transmit a predetermined torque (for example, 300 Nm). In the first shock absorber 15C having the groove 3, the strength of the portion corresponding to the groove 3 with respect to torque is reduced. Although the first shock absorber 15C is designed in consideration of a sufficient safety factor, there is a possibility that when the first shock absorber 15C rusts, the first shock absorber 15C cannot withstand a predetermined torque. is there. On the other hand, in the first shock absorbing part 15C, the covering material 5 suppresses the generation of rust on the surface facing the groove 3. The strength reduction of the portion corresponding to the groove 3 of the first shock absorbing portion 15C is suppressed. The third modification is particularly effective when it is placed in a place where water such as rain may be splashed.

  Moreover, the coating | covering material 5 covers the main surface 150 which is a surface outside the groove | channel 3 of 15 C of 1st shock absorption parts.

  As described above, when a predetermined axial load is applied to the intermediate shaft 85, the first shaft 1 and the second shaft 2 move relatively. If a bending moment is also applied to the intermediate shaft 85, the second shaft 2 may be caught by the first shock absorber 15C. On the other hand, since the main surface 150 is covered with the covering material 5, the friction between the second shaft 2 and the first shock absorbing portion 15C is reduced. For this reason, even if the second shaft 2 is in contact with the first shock absorber 15C, the second shaft 2 is not easily caught by the first shock absorber 15C. For this reason, the movement of the second shaft 2 becomes smooth.

(Fourth modification)
FIG. 15 is an enlarged cross-sectional view of the first shock absorber in the fourth modification. Note that the same components as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 15, in the fourth modification, the filler 6 is provided in the groove 3. For example, the filler 6 is disposed in all of the plurality of grooves 3. For example, the depth of the filler 6 is equal to the depth H of the groove 3 (see FIG. 6). The filler 6 is preferably resin or rubber. Furthermore, the filler 6 is preferably rubber that is a closed cell. The Young's modulus of the filler 6 is smaller than the Young's modulus of the first shock absorber 15D. When a bending moment is applied to the first shock absorber 15D, the filler 6 is easily deformed.

  Note that the depth of the filler 6 may be smaller than the depth H of the groove 3 (see FIG. 6). That is, the volume of the filler 6 embedded in one groove 3 may be smaller than the volume of one groove 3. The filler 6 preferably covers the bottom surface 35, the first connection surface 36 and the second connection surface 37. Further, the groove 3 may be provided with both the filler 6 and the covering material 5 described in the third modification. That is, the covering material 5 may cover the first shock absorbing portion 15 </ b> D and the filler 6 may cover the covering material 5. The filler 6 may be grease, for example. In this case, the viscosity of the grease is preferably higher.

  As described above, the steering device 80 of the fourth modification includes the filler 6 disposed in the groove 3.

  In the first shock absorbing portion 15D of the fourth modified example, the filler 6 makes it difficult for water to enter the groove 3. For this reason, generation | occurrence | production of the rust on the surface of 1st shock absorption part 15D which faces the groove | channel 3 is suppressed. The strength reduction of the portion corresponding to the groove 3 of the first shock absorber 15D is suppressed. The fourth modification is particularly effective when it is disposed in a place where water such as rain may be splashed.

  The filler 6 is a resin. Thereby, it becomes difficult for the filler 6 to inhibit the deformation of the first shock absorber 15D.

  The filler 6 is rubber. Thereby, it becomes difficult for the filler 6 to inhibit the deformation of the first shock absorber 15D.

  The filler 6 is a closed cell. Thereby, an increase in the weight of the first shock absorber 15D is suppressed.

  The volume of the filler 6 is the same as the volume of the groove 3.

  Thereby, since the groove | channel 3 is filled with the filler 6, the outer peripheral surface of 1st shock absorption part 15D becomes smooth. Friction between the second shaft 2 and the first shock absorber 15D is reduced. For this reason, even if the second shaft 2 is in contact with the first shock absorber 15D, the second shaft 2 is not easily caught by the first shock absorber 15D. For this reason, the movement of the second shaft 2 becomes smooth.

(5th modification)
FIG. 16 is a cross-sectional view of an intermediate shaft of a fifth modification. Note that the same components as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 16, in the fifth modification, the first shaft 1 is positioned in front of the second shaft 2. The first shaft 1 includes a stopper 14 and a base portion 19. The stopper 14 protrudes in the radial direction from the outer peripheral surface of the base portion 13. The stopper 14 is formed integrally with the base portion 13. The stopper 14 overlaps the end surface of the second fitting portion 21 when viewed from the axial direction. The stopper 14 is located behind the first shock absorber 15. For this reason, the distance from the end surface of the second fitting portion 21 to the stopper 14 is smaller than the distance from the end surface of the second fitting portion 21 to the first shock absorbing portion 15. The base 19 is located in front of the first shock absorber 15 and is connected to the second universal joint 86. The diameter of the base 19 is constant and is equal to the diameter of the base 11.

  When the first shaft 1 and the second shaft 2 move relative to each other, the stopper 14 comes into contact with the end face of the second fitting portion 21. The stopper 14 regulates the relative movement amount of the first shaft 1 and the second shaft 2. Since the stopper 14 is located behind the first shock absorber 15, the stopper 14 contacts the second fitting portion 21 before the first shock absorber 15 enters the second shaft 2. For this reason, the first shaft 1 can be bent after moving relative to the second shaft 2.

  The stopper 14 may be provided on the second shaft 2. For example, the stopper 14 may be provided on the inner peripheral surface of the second shaft 2 and overlap the first fitting portion 17 when viewed from the axial direction. In such a case, the distance from the end surface of the first fitting portion 17 to the stopper 14 is preferably smaller than the distance from the end surface of the second fitting portion 21 to the first shock absorbing portion 15. Accordingly, the first fitting portion 17 contacts the stopper 14 before the first shock absorbing portion 15 enters the second shaft 2. For this reason, the first shaft 1 can be bent after moving relative to the second shaft 2.

  The stopper 14 may be connected to the base 13 by welding or the like. A C-type retaining ring or an E-type retaining ring may be used as the stopper 14.

  As described above, the intermediate shaft 85E includes the stopper 14 that regulates the relative movement amount of the first shaft 1 and the second shaft 2.

  As a result, the relative movement amount of the first shaft 1 and the second shaft 2 can be adjusted, so that an excessive load is prevented from being applied to the second shaft 2.

DESCRIPTION OF SYMBOLS 1 1st shaft 11, 13, 19 Base 12 2nd shock absorption part 121 1st connection part 125 Small diameter part 129 2nd connection part 15, 15A, 15B, 15C, 15D 1st shock absorption part 150 Main surface 17 1st fitting Joint 170 Concave portion 17a Serration 2 Second shaft 21 Second fitting portion 21a Serration 23 Large diameter portion 25 Base portion 3, 3A, 3B Groove 31, 31B First side surface 33, 33B Second side surface 35, 35B Bottom surface 36, 36B First 1 connection surface 37, 37B 2nd connection surface 4 convex portion 5 covering material 6 filler 80 steering device 81 steering wheel 82 steering shaft 82a input shaft 82b output shaft 83 steering force assist mechanism 84 first universal joint 85, 85E intermediate shaft 86 Second universal joint 87 Pinion shaft 88 Steering gear 8 a pinion 88b rack 89 tie rod 90 ECU
92 Speed reducer 93 Electric motor 94 Torque sensor 95 Vehicle speed sensor 98 Ignition switch 99 Power supply

Claims (14)

A first universal joint;
A second universal joint disposed on the front side of the first universal joint;
An intermediate shaft connecting the first universal joint and the second universal joint;
With
The intermediate shaft includes a first shaft that is a solid member, and a cylindrical second shaft that is detachably coupled to the first shaft,
The first shaft includes a shock absorbing portion having a groove on an outer peripheral surface thereof. The first shaft includes a first fitting portion having serrations on an outer peripheral surface;
The second shaft includes a second fitting portion having serrations on an inner peripheral surface,
The first fitting portion fits into the second fitting portion;
The steering device according to claim 1, wherein a maximum diameter of the impact absorbing portion is smaller than a minimum diameter of the first fitting portion. The shock absorber includes a plurality of the grooves,
The steering device according to claim 1 or 2, wherein the groove is annular. The steering device according to claim 1, wherein the groove has a spiral shape. The maximum width of the groove is 1 mm or more and 3 mm or less,
In a cross section obtained by cutting the intermediate shaft along a plane perpendicular to the radial direction, at least a part of the surface of the shock absorbing portion facing the groove has an arc having a radius of curvature of 0.2 mm to 1.0 mm. The steering apparatus according to any one of claims 1 to 4. The steering device according to any one of claims 1 to 5, wherein a width of the groove decreases toward a bottom of the groove. A covering material covering at least a part of the surface of the shock absorbing portion facing the groove;
The steering device according to any one of claims 1 to 6, wherein the coating material is a rust-proof coating. The steering apparatus according to claim 7, wherein the covering material covers a main surface that is a surface outside the groove of the shock absorbing portion. The steering device according to claim 1, further comprising a filler disposed in the groove. The steering device according to claim 9, wherein the filler is resin. The steering device according to claim 9, wherein the filler is rubber. The steering device according to claim 11, wherein the filler is a closed cell body. The steering device according to any one of claims 9 to 12, wherein a volume of the filler is the same as a volume of the groove. An intermediate shaft used in a steering device,
A first shaft that is a solid member;
A cylindrical second shaft removably coupled to the first shaft;
With
The first shaft includes an impact absorbing portion having a groove on an outer peripheral surface.

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