JP2019006130A - Steering device and intermediate shaft - Google Patents

Abstract

To provide a steering device absorbing shock by an intermediate shaft that can be easily manufactured and can easily change deformation characteristics.SOLUTION: A steering device comprises: a first universal joint; a second universal joint arranged at the front side than the first universal joint; and an intermediate shaft that is the solid member connecting the first universal joint and the second universal joint. The intermediate shaft is provided with a shock absorbing part having grooves in the outer peripheral surface.SELECTED DRAWING: Figure 3

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 invention has been made in view of the above-described problems, and an object of the present invention 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 apparatus according to an aspect of the present invention includes a first universal joint, a second universal joint disposed in front of the first universal joint, the first universal joint, and the first universal joint. An intermediate shaft that is a solid member that connects the two universal joints, and the intermediate shaft includes an impact absorbing portion having a groove on the outer peripheral surface.

  This eliminates the need for a mold when forming the impact absorbing portion, and thus facilitates the formation of the impact absorbing portion. Further, the deformation characteristics of the shock absorbing portion change according to the shape of the groove of the shock absorbing portion. Since it is easy to change the shape of the groove, it is easy to adjust the deformation characteristics of the 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.

  As a desirable mode of the steering device, it is desirable that 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 impact absorbing portion. For this reason, since the range of the part which a shock-absorbing part deform | transforms tends to become large, the shock-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 a steering device, it is desirable that the groove is spiral.

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

  As a desirable mode of the steering device, the maximum width of the groove is 1 mm or more and 3 mm or less. It is desirable that at least a part of the circular arc has a radius of curvature of 0.2 mm to 1.0 mm.

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

  As a desirable mode of the steering device, it is desirable that the width of the groove decreases toward the bottom of the groove.

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

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

  This eliminates the need for a mold when forming the impact absorbing portion, and thus facilitates the formation of the impact absorbing portion. Further, the deformation characteristics of the shock absorbing portion change according to the shape of the groove of the shock absorbing portion. Since it is easy to change the shape of the groove, it is easy to adjust the deformation characteristics of the shock absorber. Therefore, the intermediate shaft can be easily manufactured and the deformation characteristics can be easily changed.

  ADVANTAGE OF THE INVENTION According to this invention, the steering device which absorbs an impact with the intermediate shaft which can be manufactured easily and can change a deformation | transformation characteristic easily can be provided.

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 side view of the intermediate shaft of the present embodiment. FIG. 4 is a cross-sectional view taken along the line AA in FIG. FIG. 5 is an enlarged view of the periphery of the groove in FIG. FIG. 6 is a perspective view of the intermediate shaft after bending. FIG. 7 is a side view of the impact absorbing portion in the intermediate shaft of the first modified example. FIG. 8 is an enlarged view of the peripheral portion of the groove in the intermediate shaft of the second modified example.

  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 side view of the intermediate shaft of the present embodiment. FIG. 4 is a cross-sectional view taken along the line AA in FIG. FIG. 5 is an enlarged view of the periphery of the groove in FIG.

  The intermediate shaft 85 is a substantially cylindrical solid member. For example, the intermediate shaft 85 is formed of S35C which is carbon steel for machine structure (SC steel (Carbon Steel for Machine Structural Use)). As shown in FIG. 3, the intermediate shaft 85 includes a base portion 11, an impact absorbing portion 15, and a base portion 19.

  The base 11 is connected to the first universal joint 84. The diameter of the base 11 is constant. The shock absorber 15 is located in front of the base 11. The shock absorber 15 is located at the center of the intermediate shaft 85 in the axial direction of the intermediate shaft 85. The base 19 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.

  In the following description, the axial direction of the intermediate shaft 85 is simply described as the axial direction, and the direction orthogonal to the axial direction is described as the radial direction. 4 and 5 are cross-sectional views in which the intermediate shaft 85 is cut along a plane orthogonal to the radial direction.

  As shown in FIG. 4, the impact absorbing portion 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 shock absorbing portion 15 at a position corresponding to the convex portion 4 is equal to the diameters of the base portion 11 and the base portion 19.

  As shown in FIG. 5, the shock absorbing portion 15 includes a first side surface 31, a second side surface 33, a bottom surface 35, a first connection surface 36, and a second connection surface 37 as surfaces facing the groove 3. ,including. 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. 5, the first connection surface 36 and the second connection surface 37 draw the same arc. The radius of curvature C1 of the circular arc drawn by the first connection surface 36 and the second connection surface 37 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 shock absorber 15 is designed to transmit a torque of 300 (Nm), for example. When the intermediate shaft 85 is formed of S35C, the diameter D2 of the shock absorber 15 at a position corresponding to the bottom of the groove 3 is 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.

  FIG. 6 is a perspective view of the intermediate shaft after bending. A load is applied to the steering gear 88 during the primary collision of the vehicle. Bending stress is generated in the intermediate shaft 85 due to the load applied to the steering gear 88. At this time, stress concentration occurs on the first connection surface 36 and the second connection surface 37, so that the shock absorbing portion 15 bends with the first connection surface 36 and the second connection surface 37 as a starting point. 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 impact absorbing portion 15 is bent, the impact due to the collision is absorbed. As a result, the impact transmitted to the steering wheel 81 is reduced.

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

  In addition, the groove | channel 3 of the 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, the surface of the shock absorbing portion 15 at a position corresponding to the bottom of the groove 3 may draw a semicircle in a cross section obtained by cutting the intermediate shaft 85 along a plane perpendicular to the radial direction. 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 shock absorbing portion 15 is not necessarily the number shown in the figure. The shock absorber 15 only needs to have at least one groove 3.

  Note that the diameter D1 of the impact 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 D1 should just be larger than the diameter D2 of the impact-absorbing part 15 in the position corresponding to the bottom of the groove | channel 3 at least. The diameter D1 may be smaller than the diameter of the base 11 or may be larger than the diameter of the base 11.

  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 that is a solid member that connects the two. The intermediate shaft 85 includes the impact absorbing portion 15 having the groove 3 on the outer peripheral surface.

  Thereby, since a metal mold is not required for forming the shock absorbing portion 15, the shock absorbing portion 15 can be easily formed. Further, the deformation characteristics of the shock absorbing portion 15 change according to the shape of the groove 3 of the shock absorbing portion 15. Since it is easy to change the shape of the groove 3, it is easy to adjust the deformation characteristics of the 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.

  Further, in the steering device 80, the impact absorbing unit 15 includes a plurality of grooves 3. The groove 3 is annular.

  Thereby, when bending stress acts on the intermediate shaft 85, stress concentration occurs in a plurality of portions of the shock absorbing portion 15. For this reason, since the range of the part which the 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 along a plane perpendicular to the radial direction, at least a part of the surface of the impact absorbing portion 15 facing the groove 3 is an arc having a radius of curvature of 0.2 mm to 1.0 mm. Draw.

  Thereby, extreme stress concentration does not occur in the impact absorbing portion 15, and the impact absorbing portion 15 is easily bent.

(First modification)
FIG. 7 is a side view of the impact absorbing portion in the intermediate shaft of the first 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.

  As shown in FIG. 7, the impact absorbing portion 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 bending stress acts on the intermediate shaft 85, stress concentration occurs at a plurality of portions of the impact absorbing portion 15A. For this reason, since the range of the portion where the shock absorbing portion 15A is deformed 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. 8 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 shock absorbing portion 15B of the second modification includes a plurality of grooves 3B. As shown in FIG. 8, the 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 37B as surfaces facing the groove 3B. ,including. 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.

11, 19 Base portion 15, 15A, 15B Shock absorbing portion 3, 3A, 3B Groove 31, 31B First side surface 33, 33B Second side surface 35, 35B Bottom surface 36, 36B First connection surface 37, 37B Second connection surface 4 Convex Part 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 Intermediate shaft 86 Second universal joint 87 Pinion shaft 88 Steering gear 88a 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 (6)

A first universal joint;
A second universal joint disposed on the front side of the first universal joint;
An intermediate shaft that is a solid member connecting the first universal joint and the second universal joint;
With
The intermediate shaft includes a shock absorbing portion having a groove on an outer peripheral surface thereof. The shock absorber includes a plurality of the grooves,
The steering device according to claim 1, 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 3. The steering device according to any one of claims 1 to 4, wherein a width of the groove decreases toward a bottom of the groove. An intermediate shaft that is a solid member used in a steering device,
An intermediate shaft having an impact absorbing portion having a groove on the outer peripheral surface.

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