This application is a U.S. national phase application filed under 35 U.S.C. §371 of International Application PCT/JP2012/076247, filed on Oct. 10, 2012, designating the United States, which claims priority from Japanese Application Number 2011-223616, filed Oct. 11, 2011, Japanese Application Number 2012-117067, filed May 23, 2012, Japanese Application Number 2012-131939, filed Jun. 11, 2012, and Japanese Application Number 2012-157304, filed Jul. 13, 2012, which are hereby incorporated herein by reference in their entirety.
The present invention relates to a steering column of an automobile steering apparatus, and to a manufacturing method thereof.
As a steering apparatus for applying a steering angle to steered wheels (except in the case of special vehicles such as a forklift, the steered wheels are normally the front wheels), construction such as illustrated in
In the construction illustrated in
On the other hand, as a countermeasure against theft of an automobile, automobiles are equipped with various kinds of anti-theft apparatuses. As one kind of such an apparatus, a steering lock apparatus, that makes it impossible to operate the steering wheel unless a proper key is used, is widely used.
When this kind of steering lock apparatus 12 is assembled in a steering apparatus, the lock unit 13 is provided on the outer-diameter side of the steering column 2a, and the key-lock collar 15 is provided on the inner-diameter side of the steering column 2a. Therefore, in order to place the key-lock collar 15 on the inner-diameter side of the steering column 2a so as to be able to rotate, and to securely engage or disengage the lock pin 16 and the key-lock collar 15 without making the stroke of the lock pin 16 too large, it is necessary to make the thickness of the steering column 2a where the steering lock apparatus 12 is assembled thin by making the outer diameter of the steering column 2a small in at least the portion where the steering lock apparatus 12 is assembled, and making the inner diameter thereof larger.
In consideration of the situation described above, it is the object of the present invention to achieve construction of a steering column in which the thickness of part of the steering column can be made thin, and for which the overall strength can be secured.
The steering column of the present invention has an overall hollow and cylindrical shape, and all or part thereof is formed using a column member. This column member has:
a main body portion that is made of a light metal alloy such as aluminum alloy, magnesium alloy and the like and that has one-side end section and another-side end section; and
a cylindrical member that is made of an iron alloy, that has one-side end section and another-side end section, and that is joined in the axial direction with respect to the main body portion by fitting and fastening the other-side end section of the cylindrical member inside the one-side end section of the main body portion, the inner diameter of an end surface of the other-side end section of the cylindrical member being smaller than the inner diameter of a portion of the other-side end section of the cylindrical member that constitutes a joined section between the main body portion and the cylindrical member. Here, the one-side means one side in the axial direction of the steering column, and the other-side means the opposite side in that axial direction.
Preferably, the inner diameter of the other-side end section of the cylindrical member is equal to or greater than the inner diameter of a portion of the main body portion that is separated in the axial direction from the joined section.
Moreover, it is preferable to engage a convex section that is provided on the inner circumferential surface of the one-side end section of the main body portion with a concave section that is provided on the outer circumferential surface of the other-side end section of the cylindrical member.
Alternatively, it is preferable to engage a concave section that is provided on the inner circumferential surface of the one-side end section of the main body portion with a convex section that is provided on the outer circumferential surface of the other-side end section of the cylindrical member.
The concave section can be at least one concave section that is provided on part in the axial direction of the outer circumferential surface of the other-side end section of the cylindrical member, and in part in the circumferential direction thereof; and is depressed inward in the radial direction. However, preferably, the concave section is composed of a concave groove in the axial direction that extends in the axial direction and is provided in at least one location in the circumferential direction.
Alternatively or additionally, the concave section can be composed of a concave groove in the circumferential direction that extends in the circumferential direction and is provided in at least one location in the axial direction.
Furthermore, the concave section can be a knurling pattern that is formed by performing a knurling process on the outer circumferential surface of the other-side end section of the cylindrical member.
The steering column of the present invention is preferably used in a steering apparatus having a steering lock apparatus, and in that case, a lock through hole of the steering apparatus is provided at one location in the middle section in the axial direction of the cylindrical member.
The manufacturing method for a steering column of the present invention is characterized in obtaining the column member by the following steps. That is, this method comprises steps of inserting the other-side end section of the cylindrical member through an insertion hole that is open in one-side end surface of a mold such that the other-side end section of cylindrical member protrudes inside the mold; inserting one-side end section of a core into the other-side end section of the cylindrical member; obtaining the column member by feeding molten metal into the mold and forming the main body portion and joining the one-side end section of the main body portion to the other-side end section of the cylindrical member by way of the joined section. These steps can be performed in different orders as long as there is no contradiction.
Preferably, the method for manufacturing a steering column of the present invention has a further step of forming the main body portion such that the inner diameter of the end surface of the other-side end section of the cylindrical member is smaller than the inner diameter of the portion of the main body portion that is separated in the axial direction from the joined section, and after forming the main body portion, performing a machining process on the inner-diameter side portion of the tip-end section of the other-side end section of the cylindrical member such that the inner diameter of the other-side end surface of cylindrical member is equal to or greater than the inner diameter of the portion of the main body portion that is separated in the axial direction from the joined section.
In one embodiment of the method for manufacturing a steering column of the present invention, a concave section is provided on the outer circumferential surface of the other-side end section of the cylindrical member, and when forming the main body portion, a convex section is formed on the inner circumferential surface of the one-side end section of the main body portion by feeding part of the molten metal into the concave section. In the case where the concave section is composed of the concave groove in the axial direction, it is preferable to form this concave groove in the axial direction by a machining process, and in the case where the concave section is composed of the concave groove in the circumferential direction, it is preferable to form this concave groove in the circumferential direction by a turning process. On the other hand, in another embodiment of the method for manufacturing a steering column of the present invention, a convex section is provided on the outer circumferential surface of the other-side end section of the cylindrical member, and when forming the main body portion, a concave section is formed on the inner circumferential surface of the one-side end section of the main body portion by feeding part of the molten metal into a portion around the convex section.
More preferably, the method for manufacturing a steering column of the present invention has a further step of performing a drawing process on the tip-end section of the other-side end section of the cylindrical member before inserting the other-side end section of the cylindrical member through the insertion hole of the mold, and providing the concave groove in the axial direction on the outer circumferential surface of the other-side end section of the cylindrical member at the same time of making the inner diameter of the other-side end surface of the cylindrical member smaller than the inner diameter of the portion of the other-side end section of the cylindrical member that constitutes the joined section between the main body portion and the cylindrical member.
Particularly, in the case where the concave section is composed of at least one concave section that is depressed inward in the radial direction, the concave section can be formed by performing a pressing process on the outer circumferential surface of the other-side end section of the cylindrical member.
In this way, the steering column of the present invention is a steering column having an overall hollow and cylindrical shape, and the column member constituting at least part of this steering column has a main body portion that is made of a light metal alloy, and a cylindrical member that is made of an iron alloy, and is joined in the axial direction with respect to the main body portion by fitting and fastening the other-side end section of the cylindrical member inside the one-side end section of the main body portion; the inner diameter of the other-side end section of the cylindrical member is equal to or greater than the inner diameter of the portion of the main body portion that is separated in the axial direction from the joined section between the main body portion and the cylindrical member, and the thickness of the cylindrical member is substantially constant except for the inner circumferential edge of the tip-end section of the front-end section of the cylindrical member and the rear-end section thereof where a bearing is locked.
The steering apparatus of the present invention has: a steering column that is supported by a vehicle body; a steering shaft that is supported on the inner-diameter side of the steering column so as to be able to rotate; and a steering lock apparatus that is provided between the steering column and the steering shaft, and that substantially prevents the steering shaft from rotating inside the steering column during operation; and particularly, the steering column of the present invention is used as this steering column.
With the steering column of the present invention, it is possible to secure the strength of the steering column while making the thickness of part of the steering column thin. In other words, a portion near one side of the column member constituting this steering column is composed of a cylindrical member that is made of an iron alloy, so it is possible to secure the strength of the portion near the one side even though the thickness of this portion is made to be thin. On the other hand, the portion near the other side of the column member is composed of a main body portion that is made of a light metal alloy such as aluminum alloy, magnesium alloy and the like, so the overall weight of the steering column does not increase excessively.
Moreover, it is possible to make the inner diameter of at least the other-side end section of the cylindrical member constituting the portion near the one side of the column member of the steering column larger than the inner diameter of the portion of the main body portion that is separated in the axial direction from the joined section between the main body portion and the cylindrical member, except for the tip-end section of the other-side end section of the cylindrical member. Furthermore, when performing a machining process on the inner diameter of the joined section between the main body portion and the cylindrical member, except for the tip-end section of the other-side end section of the machining is not performed on the cylindrical member having thin thickness, so it is possible to prevent a decrease in strength of the cylindrical member.
In addition, the steering column of the present invention does not have complex construction, so can be industrially produced with good efficiency and at low cost.
In this example, the outer column 10b is formed by joining together in the axial direction a main body portion 18 that is made of a light alloy such as an aluminum alloy, magnesium alloy or the like, and a cylindrical member 19 that is made of an iron alloy such as carbon steel. In other words, the front-end section 20, which is the other-side end section (left side in
In order to manufacture the steering column of this example, by performing a drawing process on the tip-end section of the front-end section 20 of the cylindrical member 19, the inner diameter of the front-end surface 21 of the cylindrical member 19, which is the end surface of the other-side end section, is made smaller than the portion of the front-end section 20 of the cylindrical member 19 that constitutes the joining section between the main body portion 18 and the cylindrical member 19, or in other words, is smaller than the portion of the front-end section 20 of the cylindrical member 19 where the drawing process was not performed. This portion includes a portion of the front-end section 20 of the cylindrical member 19 that is located on the inner-diameter side of the portion where the rear-end surface is formed, which is the end surface on the one side of the main body portion 18 (portion where the inside end surface of the mold 23 (left side surface of the tip-end section of the mold 23 in
Then, a core 26 is inserted inside the insertion hole 25 of the mold 23 from the other side (opposite side in the axial direction form the end surface 24), and the tip-end section 27, which is the one-side end section of the core 26, is inserted into and fitted inside the front-end section 20 of the cylindrical member 19. When doing this, a stepped surface 29 that is provided between the tip-end section 27 and base-end section 28 of the core 26 comes in contact with the front-end surface 21 of the cylindrical member 19. Therefore, the internal space of the mold 23 is defined by the inner circumferential surface and inner side surface of the mold 23, the front-end surface 21 of the front-end section 20 and the outer circumferential surface of the cylindrical member 19, and the outer circumferential surface of the core 26. In this example, the front-end surface 21 of the cylindrical member 19 is an opposing surface that comes in contact with the stepped surface 29 of the core 26, so as illustrated in
By feeding molten light alloy such as aluminum alloy, magnesium alloy or the like into the mold 23 in a state in which the stepped surface 29 of the core 26 is in contact with the front-end surface 21 of the cylindrical member 19, the rear-end section of the main body portion 18 and the front-end section 20 of the cylindrical member 19 are joined in the axial direction, and the main body portion 18 is formed. At this time, by feeding part of the molten metal into the concave section 22 of the cylindrical member 19, a convex section 31 is formed on the inner circumferential surface of the rear-end section of the main body portion 18. In this example, the joined section between the rear-end section of the main body portion 18 and the front-end section of the cylindrical member 19 are formed by fitting these portions together and by engaging the concave section 22 and convex section 31. However, construction in which the joined section is formed by only one of these is also included in the present invention. In order to insert the inner shaft into the inner-diameter side of the cylindrical member 19 so as to be able to rotate freely, a rolling bearing 33 (see
After the outer column 10b that was obtained by forming the main body portion 18 is removed from the mold 23, a machining process is performed on the inner peripheral edge of the tip-end section of the front-end section 20 of the cylindrical member 19 that protrudes further inward in the radial direction than the inner circumferential surface of the main body portion 18, and the inner diameter of the cylindrical member 19 of at least the portion near the front end (portion except for the small-diameter section 34 that was formed for fitting and fastening the outer ring of the rolling-bearing 33 for inserting the inner shaft into the inner-diameter side of the outer column 10b so as to be able to rotate freely) is made to be equal to or greater than the inner diameter of the portion of the main body portion 18 that is separated in the axial direction from the joined section between the main body portion 18 and the cylindrical member 19 (portion that is fitted around the outside of the front-end section 20 of the cylindrical section 19). A machining process can be performed on the portion of the main body portion 18 on the inner-diameter side of the portion that is adjacent in the axial direction to the joined section until the inner diameter of the main body portion 18 of the portion that is separated in the axial direction from the joined section is within the range of being equal to or less than the inner diameter of the portion near the front end of the cylindrical member 19. By performing this kind of machining process, a forward facing stepped surface between the inner circumferential surface of the main body portion 18 through which the inner column 32 is passed through and the front-end edge of the cylindrical member 19 is eliminated such that displacement in the forward direction of the outer column 10b during a secondary collision can be performed smoothly, and thus it is possible to more completely protect the driver during a collision accident. Moreover, performing a machining process on the inner-diameter side portion of the rear-end section of the main body portion 18 that is adjacent to the joined section is done for convenience in order to simplify processing, and this kind of machining process can substantially be evaluated as being a machining process that is performed only on the inner peripheral edge of the front-end section of the cylindrical member 19. In this example, the diameter of the inscribed circle of the protrusions in the portion on the inner circumferential surface of the front-end section 20 of the cylindrical member 19 that corresponds to the concave sections 22 is taken beforehand to be equal to or greater than the inner diameter of the portion of the main body portion 18 that is separated in the axial direction from the joined section between the main body portion 18 and the cylindrical member 19, so regardless of whether or not a machining process is performed on these protrusions, the tip ends of these protrusions do not protrude further inward in the radial direction than the inner circumferential surface of the main body portion 18.
In the case of the steering column of this example, it is possible to make the thickness of the rear half section of the outer column 10b of the steering column in which the steering lock apparatus 12 (see
Moreover, the concave section 22 that is formed on the outer circumferential surface of the front-end section 20 of the cylindrical member 19 engages with the convex section 31 that is formed on the inner circumferential surface of the rear-end section of the main body portion 18, so it is possible to ensure the joint strength in the axial direction between the main body portion 18 and the cylindrical member 19. Furthermore, in the circumferential direction as well, with the lock pin 16 engaged with the engagement concave section 14 of the key-lock collar 15, it is possible to improve the torsion rigidity of the joined section between the main body portion 18 and cylindrical member 19 due to the engagement between the concave section 22 and convex section 31 even when a large force is applied in an attempt to rotate the steering wheel 4. Instead of the concave section 22 that is recessed inward in the radial direction on the outer circumferential surface of the front-end section 20 of the cylindrical member 19, it is possible to provide a convex section that protrudes outward in the radial direction to engage with a concave section that is provided on the inner circumferential surface of the rear-end section of the main body portion 18.
A drawing process is performed on the tip-end section of the front-end section 20 of the cylindrical member 19, and with the inner diameter of the front-end surface 21 of the cylindrical member 19 less than the inner diameter of the portion of the front-end section 20 of the cylindrical member 19 that is located on the inner-diameter side of the portion where the rear-end surface of the main body portion 18 is formed, the main body portion 18 is formed by casting. Therefore, it is possible to effectively ensure the strength of the joined section between the main body portion 18 and the cylindrical member 19. The advantage of forming the main body portion 18 in a state in which the inner diameter of the front-end surface 21 of the cylindrical member 19 is less than the inner diameter of the portion of the cylindrical member 19 that is located on the inner-diameter side of the portion where the rear-end surface of the main body portion 18 is formed, will be explained using
In this reference example, the inner diameter of the front-end surface 21a of the cylindrical member 19a is the same as the inner diameter of the portion of the cylindrical member 19a that is located on the inner-diameter side of the portion where the rear-end surface of the main body portion 18a is formed. Under this kind of condition, as illustrated in
On the other hand, in the construction of the first example, when performing a machining process on the portion on the inner-diameter side of the joined section between the main body portion 18 and the cylindrical member 19, the portions where this machining process is performed are only the peripheral edge of the tip-end section of the front-end section 20 of the cylindrical member 19, and the portion of the inner-diameter side portion of the main body portion 18 that is adjacent to the joined section between the main body portion 18 and the cylindrical member 19. Except for the tip-end section of the front-end section 20, it is not necessary to machine away the joined section, including the portion of the cylindrical member 19 that is located further on the rear-end side than the joined section. Therefore, as illustrated in
Moreover, a machining process is performed on the inner peripheral edge of the tip-end section of the front-end section 20 of the cylindrical member 19, and the inner diameter of the portion near the front end of the cylindrical member 19 is equal to or greater than the inner diameter of the portion of the main body portion 18 that is separated in the axial direction from the joined section. The cylindrical inner column 32 is fitted inside the front-end section (left-end section in
Moreover, during manufacturing, the inner diameter of the front-end surface 21 of the cylindrical member 19 is made to be less than the portion of the cylindrical member 19 that is located on the inner-diameter side of the portion where the rear-end surface of the main body portion 18 is formed, so when forming the main body portion 18 by feeding molten light alloy into the mold 23, the molten metal is not fed into the inner circumferential side of the cylindrical member 19, and the inner circumferential surface of the cylindrical member 19 is prevented from becoming a rough surface due to light alloy adhering to the surface.
In the case of the third example illustrated in
In this example, in order to provide the outer ring of the rolling bearing 33 (see
When placing the cylindrical member 19f into the mold 23 and forming the main body portion 18 (see
Moreover, when performing the drawing process on the tip-end section of the front-end section 20 of the cylindrical member 19g, it is possible to form the concave grooves 42a in the axial direction at the same time by a drawing process. In this case, it is possible to reduce the manufacturing cost by reducing the manufacturing processes. When forming the concave groove 41a in the circumferential direction by a pressing process and forming the concave grooves 42a in the axial direction by a drawing process, the diameter of the inscribed circle of protrusions that are located in portions on the inner circumferential surface of the front-end section 20 of the cylindrical member 19f that correspond to the concave groove 41a in the circumferential direction and concave grooves 42a in the axial direction is equal to or greater than the inner diameter of the portion of the main body portion 18 that is separated from the joined section between the main body portion 18 and the cylindrical member 19, and the tip-end sections of these protrusions do not protrude further inward in the radial direction than the inner circumferential surface of the main body portion 18. The construction and function of the other parts are the same as in the sixth example.
The knurling pattern can be formed by a rolling process, however, preferably is formed by a machining process. In other words, when forming a knurling pattern on the outer circumferential surface of the front-end section of the cylindrical member 19i, which is a pipe material having a thin thickness, using a rolling process, there is a possibility that the outer circumferential surface of the front-end section of the cylindrical member 19i, where the rolling process is performed, will deform (warp). On the other hand, by forming a knurling pattern by a machining process, deformation of the portion where machining process is performed is prevented, and the rough surface section 43 can be formed easily and highly precisely. As a method for forming the knurling pattern with this kind of machining process, for example, Quick Knurling by Yamada Engineering Co., Ltd. can be employed.
In the ninth example, a rough surface section 43 for preventing relative rotation between the cylindrical member 19i and the main body portion 18 and for preventing the cylindrical member 19i from falling out of the main body portion 18 is formed by a knurling process, so it is possible to ensure the plate thickness of the cylindrical member 19i at the joined section between the main body portion 18 and the cylindrical member 19i, and ensure the rigidity of the joined section. In other words, when a concave groove 41 in the circumferential direction is formed by a turning process, and concave grooves 42 in the axial direction are formed by a machining process as in the case of the sixth example, if the plate thickness of the cylindrical member 19 is not sufficiently thick, the plate thickness of the cylindrical member 19 at the joined section between the main body portion 18 and the cylindrical member 19 will become thin, and there is a possibility that the rigidity of the joined section will not be sufficiently ensured. However, in this example, by forming a knurling pattern that is composed of numerous shallow infinitesimal concave grooves on the outer circumferential surface of the front-end section 20 of the cylindrical member 19i, relative rotation and falling out is prevented. The construction and function of the other parts is the same as in the first example.
Furthermore, a steering lock apparatus such as illustrated in
Number | Date | Country | Kind |
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2011-223616 | Oct 2011 | JP | national |
2012-117067 | May 2012 | JP | national |
2012-131939 | Jun 2012 | JP | national |
2012-157304 | Jul 2012 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2012/076247 | 10/10/2012 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2013/054821 | 4/18/2013 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
3210102 | Joslin | Oct 1965 | A |
3824665 | Saito | Jul 1974 | A |
4257155 | Hunter | Mar 1981 | A |
4482174 | Puri | Nov 1984 | A |
4624489 | Nakamura | Nov 1986 | A |
5537890 | Thomas | Jul 1996 | A |
5918914 | Morris | Jul 1999 | A |
6976712 | Lukach, Jr. | Dec 2005 | B2 |
7097211 | Adams | Aug 2006 | B2 |
7779945 | Allgauer | Aug 2010 | B2 |
8342579 | Hennemann et al. | Jan 2013 | B2 |
8991861 | Iwakawa | Mar 2015 | B1 |
8997602 | Tanaka | Apr 2015 | B2 |
20040118238 | Toth et al. | Jun 2004 | A1 |
20050194775 | Bastein | Sep 2005 | A1 |
20110239809 | Beneker et al. | Oct 2011 | A1 |
20110247891 | Meyer et al. | Oct 2011 | A1 |
20110256419 | Iwayama et al. | Oct 2011 | A1 |
20120160051 | Walser | Jun 2012 | A1 |
20120324965 | Yamamoto | Dec 2012 | A1 |
20130228034 | Hebenstreit | Sep 2013 | A1 |
20130276569 | Davies et al. | Oct 2013 | A1 |
20140026708 | Okada et al. | Jan 2014 | A1 |
20140127069 | Bae et al. | May 2014 | A1 |
20140150596 | Nagasawa | Jun 2014 | A1 |
20140157938 | Erhardt | Jun 2014 | A1 |
20140216197 | Erhardt et al. | Aug 2014 | A1 |
20140246847 | Nagasawa et al. | Sep 2014 | A1 |
20140311273 | Nagasawa | Oct 2014 | A1 |
20140345414 | Erhardt et al. | Nov 2014 | A1 |
Number | Date | Country |
---|---|---|
1245471 | Oct 2002 | EP |
2 273 451 | Jun 1994 | GB |
S52-171060 | Dec 1977 | JP |
H06-211137 | Aug 1994 | JP |
2005-349968 | Dec 2005 | JP |
2007-223383 | Sep 2007 | JP |
2008-265358 | Nov 2008 | JP |
2008-265646 | Nov 2008 | JP |
2009-149228 | Jul 2009 | JP |
2010-036677 | Feb 2010 | JP |
2011-073547 | Apr 2011 | JP |
2011-73547 | Apr 2011 | JP |
Entry |
---|
International Search Report from the International Bureau of WIPO for International Application No. PCT/JP2012/076247 dated Jan. 15, 2013 and English translation of the same (6 pages). |
The Extended European Search Report dated Apr. 1, 2015 for European Patent Application No. 12840514.9. |
The Japanese Office Action dated Mar. 31, 2015 for Japanese Patent Application No. 2014-022148 and English translation of the same. |
Number | Date | Country | |
---|---|---|---|
20140246847 A1 | Sep 2014 | US |