JP2008137481A - Energy absorbing type intermediate shaft and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intermediate shaft provided with impact absorbing performance stabilizing push-in load when the shaft is pushed into a tube in a vehicle collision, in an energy absorbing type intermediate shaft for connecting a steering shaft and a steering gear and its manufacturing method. <P>SOLUTION: This intermediate shaft 11 is constituted by serration-connecting a tube 13a to a shaft 12a. The shaft 12a and the tube 13a are frictionally connected by pushing and deforming an end part of the tube 13a opposed to a plane part 12b by using a punch P and a die D. When axial direction impact force acts due to the vehicle collision, etc., the shaft 12a is pushed into the tube 13a against frictional connection force to reduce the impact. The plane part 12b is adjacent to a raised part of a radius R1 and formed into a shape connected with a second surface of a smaller curvature R2 than the radius R1. A sharp edge by machining the plane part 12b and generation of galling in a connection part by burrs generated at the edge are suppressed to stabilize push-in load in the vehicle collision. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a configuration of an energy absorbing intermediate shaft for connecting a steering shaft and a steering gear of a vehicle steering apparatus, and a method for manufacturing the same.

  In the vehicle steering device that transmits the movement of the steering wheel to the steering gear, an energy absorbing intermediate shaft that absorbs impact energy and contracts the entire length when impact is applied in order to protect the driver from the impact at the time of vehicle collision Is required by law.

  FIG. 3 is a diagram for explaining an example of the configuration of the vehicle steering device that transmits the movement of the steering wheel to the steering gear. Via the shaft 101, the first universal joint 107, the intermediate shaft 110, and the second universal joint 111 are transmitted to the input shaft 112 of the steering gear, and the steering angle is given to the wheels. The steering column 103 is fixed to the lower surface of the instrument panel 106 by brackets 104 and 105, and the intermediate shaft 110 is an energy absorbing intermediate shaft whose overall length is reduced while absorbing impact energy (Patent Document 1). 2).

  FIG. 4 is an external view of the intermediate shaft 110. The intermediate shaft 110 includes a tube 108a and a shaft 109a. The tube 108a is fixedly connected to the yoke 107a of the first universal joint 107, and the shaft 109a is connected to the first shaft 108a. The yokes 111a of the two universal joints 111 are connected. A female serration is formed on the inner peripheral surface of the tube 108a, a male serration is formed on the outer peripheral surface of the shaft 109a, and the shaft 109a is fitted to the tube 108a to be serrated. With this configuration, a rotational force can be transmitted between the tube 108a and the shaft 109a, and the tube 108a and the shaft 109a are slidably coupled in the axial direction.

  Further, a flat portion 109c is formed in a part of the shaft 109a by milling, and the yoke 111a of the universal joint 111 and the shaft 109a are fixedly fastened by a pinch bolt 113 that abuts the flat portion 109c.

  When the male serration portion formed on the outer peripheral surface of the shaft 109a is milled to form the flat portion 109c, a cut end surface 109f having a sharp edge is formed in the male serration portion, and fine burrs are generated on the cut end surface 109f. . The edge of the cut end face and burrs will be described in “Problems to be solved by the invention” described later.

  FIG. 5 is a diagram for explaining an assembly process of the intermediate shaft 110. First, a shaft 109a with male serration formed on the outer peripheral surface is inserted into a tube 108a with female serration on the inner peripheral surface (see FIG. 5A), and a part of the flat portion 109c is the end of the tube 108a. Until it is exposed to the part (see FIG. 5B). In this state, the end portion of the tube 108a facing the flat portion 109c is pressed and deformed toward the shaft 109a by using a punch P and a die D (tool), and the diameter of the shaft 109a is partially reduced. The material is extruded from 108a and frictionally coupled (see FIG. 5C).

  FIG. 6 is a diagram for explaining the diameter reduction processing of the intermediate shaft 110. FIG. 6A shows a state in which a part of the flat portion 109c of the shaft 109a is inserted until it is exposed at the end of the tube 108a. It is sectional drawing. In this state, the end portion of the tube 108a facing the flat surface portion 109c is pressed and deformed toward the axial center of the shaft 109a using a punch P and a die D (tool), and the diameter is partially reduced. FIG. 6B is a cross-sectional view showing a shape after the diameter reduction processing of a portion indicated by a circle of the tube 108a in FIG.

When the shaft 109a is pushed out from the tube 108a in this state, the state shown in FIGS. 5 (c) and 6 (c) is obtained, and the above-mentioned reduced diameter tube 108a tightens the shaft 109a with a strong coupling force. Friction coupling with strong friction force. As a result, the shaft 109a and the tube 108a are normally connected to each other so that the rotational force can be transmitted and do not move in the axial direction. When the impact force acts, the shaft 109a is pushed into the tube 108a against the frictional coupling force, and the impact can be reduced.
Japanese Patent Laid-Open No. 8-258275 JP 2006-300085 A

  In the above-described conventional intermediate shaft, the shaft 109a is pushed into the tube 108a and serrated and the end portion of the tube 108a facing the flat portion 109c is pressed and deformed. When the formed male serration portion is milled to form the flat portion 109c, a cut end surface 109f having a sharp edge is formed in the male serration portion (see FIGS. 4 and 5A). Produces fine burrs.

  When there is such a sharp edge of the cut end surface 109f, the shaft or the tube is scraped by the edge when fitting to pull out the shaft from the tube, which causes galling. Further, when the fine burrs generated on the cut end surface 109f of the male serration portion are not removed, galling is also caused.

  The caulking of the fitting portion has a disadvantage that the pushing load when the tube 108a is pushed into the shaft 109a at the time of a vehicle collision is unstable, and the shock absorbing performance of the intermediate shaft is not stable. An object of the present invention is to solve the above problems.

  The present invention solves the above-mentioned problems, and the invention according to claim 1 is an energy constituted by serration coupling of a shaft having male serrations formed on the outer peripheral surface and a tube having female serrations formed on the inner peripheral surface. The absorption-type intermediate shaft, in which the male serration is formed, has a flat portion formed in a part thereof, and the flat portion is adjacent to the first rounded-up portion of the radius R1 and smaller than the radius R1. An energy-absorbing intermediate shaft having a shape in which second surfaces of curvature are connected and the second surface is connected to an outer peripheral surface of the shaft.

  The second surface may be a second rounded-up portion having a radius R2 larger than the radius R1 adjacent to the first rounded-up portion having the radius R1 of the flat surface portion.

  Further, the second surface may be a chamfered surface obtained by chamfering a first rounded-up portion having a radius R1 of the flat surface portion and an edge portion connected to the outer peripheral surface of the shaft.

  Further, the second surface may be a second rounded-up portion having a convex surface facing outward as opposed to the concave surface facing outward of the first rounded-up portion.

  Then, the energy absorbing intermediate shaft causes friction between the shaft and the tube by a diameter reducing process by pressing deformation toward the shaft axis of the tube located at a position facing at least the second surface on the tube proximity side of the flat portion. Are combined.

  Further, the energy absorbing intermediate shaft is coupled to the yoke of the universal joint with the flat portion contacting the pinch bolt.

  The invention of claim 7 is a method of manufacturing an energy absorption type intermediate shaft configured by serration coupling a shaft having a male serration formed on the outer peripheral surface and a tube having a female serration formed on the inner peripheral surface, The shaft on which the male serration is formed is connected to a second surface having a smaller curvature than the radius R1 adjacent to the first rounded-up portion having the radius R1, and the second surface is connected to the outer peripheral surface of the shaft. Forming a flat surface portion, and compressing and deforming the tube at a position facing at least the second surface on the tube proximity side of the flat surface portion toward the shaft axis, and reducing the diameter of the shaft and the tube. Is a method for producing an energy absorbing intermediate shaft.

  The energy absorption type intermediate shaft for connecting the steering shaft and the steering gear of the vehicle steering apparatus according to the present invention has a radius R1 formed on the shaft in a configuration in which the tube is pushed into the shaft constituting the intermediate shaft and serrated. Since the second surface having a curvature smaller than the radius R1 is connected adjacent to the rounded-up portion of the shaft, the shaft and the tube are suppressed by suppressing generation of a sharp edge caused by milling of the flat surface portion and burr generated at the edge. Can be suppressed, the pushing load when the tube is pushed into the shaft at the time of a vehicle collision can be stabilized, and the shock absorbing performance of the intermediate shaft can be stabilized.

  Further, according to the method for manufacturing an energy absorbing intermediate shaft according to the present invention, the second surface having a smaller curvature than the radius R1 is connected adjacent to the first rounded-up portion having the radius R1 of the flat portion formed on the shaft. Because it is formed in the shape, it is generated when fitting the shaft and the tube with the sharp edge generated by the milling of the flat part and the occurrence of burrs generated at the edge being suppressed, like the energy absorbing intermediate shaft described above. It is possible to suppress galling, stabilize the pushing load when the tube is pushed into the shaft during a vehicle collision, and stabilize the shock absorbing performance of the intermediate shaft.

  Embodiments of the present invention will be described below. Since the overall configuration of the vehicle steering device and the configuration of the intermediate shaft are the same as the configuration of the conventional intermediate shaft described above, the description thereof will be omitted here, and the configuration of the intermediate shaft and the configuration of the tube related thereto will be described.

  1 and 2 are cross-sectional views for explaining the configuration of the intermediate shaft 11 according to the embodiment of the present invention. FIG. 1 shows a case where the shaft 12a is inserted into the tube 13a to the back and the tube end is pressed and deformed. FIG. 2 is a sectional view showing the shape of the flat portion 12b of the shaft 12a.

  The intermediate shaft 11 is configured by inserting a shaft 12a having a male serration on the outer peripheral surface into a tube 13a having a female serration on the inner peripheral surface.

  A flat portion 12b is formed on the shaft 12a by milling, and a yoke of a universal joint (not shown) and the shaft 12a are fixedly fastened by a pinch bolt that comes into contact with the flat portion 12b. This point is not different from the configuration of the conventional intermediate shaft described above.

  The characteristic part of the present invention is that the raised portion of the flat surface portion 12b formed by milling is formed more gently than the conventional configuration (see FIG. 2). That is, the flat surface portion 12b is processed into a shape that is connected to the outer peripheral surface of the shaft by connecting the second surface having the curvature R2 smaller than the radius R1 adjacent to the first rounded-up portion having the radius R1. As a result, it is possible to suppress sharp edges generated by milling and galling generated when the shaft and the tube are fitted with each other by suppressing the occurrence of burrs generated at the edge, and when the shaft 12a is pushed into the tube 13a at the time of a vehicle collision. The indentation load can be stabilized and the shock absorbing performance of the intermediate shaft can be stabilized.

  The plane portion 12b has been described as a second surface having a curvature R2 smaller than the radius R1 adjacent to the first rounded-up portion having the radius R1, but the second surface is the second surface having the radius R1 of the plane portion. It is good also as a 2nd round-up part of radius R2 larger than radius R1 adjacent to 1 round-up part.

  Further, the second surface may be a chamfered surface having a chamfered edge portion connected to the first rounded-up portion having a radius R1 of the flat surface portion and the outer peripheral surface of the shaft.

  Further, the second surface may be a second rounded-up portion having a convex surface facing outward as opposed to the concave surface facing outward of the first rounded-up portion.

  The second surface only needs to have a shape in which the first rounded-up portion formed by the above-described milling and the outer peripheral surface of the shaft are smoothly connected to each other. Any shape can be used as long as the rounded-up portion and the outer peripheral surface of the shaft are smoothly connected.

  After the tube 13a is pushed in and fitted into the shaft 12a, it is inserted deeply until a part of the flat portion 12b is exposed at the end of the tube 13a (see FIG. 1). In this state, the punch P and the die D ( The end of the tube 13a facing the flat portion 12b is pressed and deformed toward the shaft 12a using a jig), and the diameter is partially reduced.

  When the shaft 12a is pushed out from the tube 13a in this state, the state shown in FIG. 2 is obtained, and the tube 13a whose diameter has been reduced as described above strongly tightens the shaft 12a and is frictionally coupled with a strong frictional force. As a result, the shaft 12a and the tube 13a are normally coupled to each other so that rotational force can be transmitted without moving in the axial direction. However, when a large axial impact force acts on the frictional coupling portion due to a vehicle collision or the like. The shaft 12a is pushed into the tube 13a against the frictional coupling force, and the impact can be reduced.

  An energy absorbing intermediate shaft for connecting a steering shaft and a steering gear of a steering apparatus for a vehicle, and a method for manufacturing the same, adjacent to a first rounded-up portion having a radius R1 of a flat portion formed on the shaft constituting the intermediate shaft Then, by processing the second surface with a curvature smaller than the radius R1 to be connected and connected, the generation of galling in the serration coupling portion is suppressed, and the pushing load when the shaft is pushed into the tube at the time of a vehicle collision is stabilized. An intermediate shaft with high shock absorption performance is provided.

Sectional drawing explaining the structure of the intermediate shaft of embodiment of this invention (The figure which shows a state when carrying out the press deformation of the tube edge part). Sectional drawing explaining the structure of the intermediate shaft of embodiment of this invention (The figure which shows the shape of the round-up part of the plane part of a shaft). The figure explaining an example of a structure of the steering apparatus for vehicles. The external view of the conventional intermediate shaft. The figure explaining the assembly process of the conventional intermediate shaft. The figure explaining the diameter reduction process of the conventional intermediate shaft.

Explanation of symbols

11 Intermediate shaft 12a Shaft 12b Flat portion 13a Tube P Punch D Die

Claims (7)

An energy absorbing intermediate shaft configured by serration coupling of a shaft having a male serration formed on the outer peripheral surface and a tube having a female serration formed on the inner peripheral surface,
The shaft on which the male serration is formed has a flat portion formed in a part thereof, and a second surface having a curvature smaller than the radius R1 is connected to the flat portion adjacent to the first rounded-up portion having the radius R1. The energy absorbing intermediate shaft is characterized in that the second surface has a shape connected to the outer peripheral surface of the shaft. 2. The energy according to claim 1, wherein the second surface is a second rounded-up portion having a radius R <b> 2 larger than the radius R <b> 1 adjacent to the first rounded-up portion having a radius R <b> 1 of the planar portion. Absorption type intermediate shaft. 2. The energy absorption type according to claim 1, wherein the second surface is a chamfered surface having a chamfered edge portion connected to a first rounded-up portion having a radius R <b> 1 of the flat portion and an outer peripheral surface of the shaft. Intermediate shaft. 2. The energy absorption according to claim 1, wherein the second surface is a second rounded-up portion having a convex surface facing outward as opposed to the concave surface facing the outside of the first rounded-up portion. Formula intermediate shaft. In the energy absorbing intermediate shaft, the shaft and the tube are frictionally coupled by a diameter reduction process by pressing deformation toward the shaft axis of the tube at a position facing at least the second surface on the tube proximity side of the flat portion. The energy absorbing intermediate shaft according to claim 1, wherein 2. The energy absorbing intermediate shaft according to claim 1, wherein the planar portion of the energy absorbing intermediate shaft is coupled to a universal joint yoke while abutting against a pinch bolt. A method of manufacturing an energy absorbing intermediate shaft configured by serration coupling a shaft having a male serration formed on the outer peripheral surface and a tube having a female serration formed on the inner peripheral surface,
The shaft on which the male serration is formed is connected to a second surface having a smaller curvature than the radius R1 adjacent to the first rounded-up portion having the radius R1, and the second surface is connected to the outer peripheral surface of the shaft. Forming a plane part with
The tube at a position facing at least the second surface on the tube proximity side of the flat portion is pressed and deformed toward the shaft axis to reduce the diameter, and the shaft and the tube are frictionally coupled. A method of manufacturing an energy absorbing intermediate shaft.

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