Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Washer structure – Spacer
Reexamination Certificate
2001-03-16
2003-12-09
Wilson, Neill (Department: 3679)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Washer structure
Spacer
C411S148000, C411S537000, C403S408100
Reexamination Certificate
active
06659702
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to improvements in a bolting structure having a non-magnesium alloy and conventional member disposed on a magnesium alloy member, the magnesium alloy member being covered with an insulator, and a bolt initially inserted through the magnesium alloy member and then into the conventional member, thereby permitting the conventional member and the magnesium alloy member to be bolted together.
2. Description of the Related Art
A magnesium alloy member is preferably used for, e.g., a reduction in weight of a vehicle because of the lightest-weight metal in practical use. A bolting structure is useful in assembling the magnesium alloy member onto a conventional member such as a steel material. However, the bolting structure suffers from problems as given below.
FIG. 12
is a cross-sectional view, illustrating a conventional bolting structure. The typical bolting structure is shown having a non-magnesium alloy and conventional member
102
disposed on a magnesium alloy member
101
, and further having a bolt
103
initially inserted through the magnesium alloy member
101
and then into the conventional member
102
, thereby fastening these two members
101
,
102
together. The bolt
103
is a low cost hexagonal bolt made of carbon steel.
In some cases, coagulation of dew in the air between a head
104
of the bolt
103
and the magnesium alloy member
101
causes water
105
to be lodged therebetween. The magnesium alloy member
101
is the most base material in potential, and a galvanic cell is formed between the magnesium alloy member
101
and the dissimilar metal or bolt
103
. As a result, an electrical current is run between the magnesium alloy member
101
and the dissimilar metal or bolt
103
through the galvanic cell, and corrosion called stray current corrosion occurs therebetween. In order to avoid such a phenomenon, the magnesium alloy member
101
must be covered with an electrically insulating material for electrically isolating the member
101
from the dissimilar metal.
FIGS. 13A and 13B
illustrate conventional bolting structures having problems to be overcome.
As shown in
FIG. 13A
, the magnesium alloy member
101
is covered with an insulator
106
such as by plating. When the bolt
103
is inserted into the member
101
, then threads (thread ridges) of the bolt
103
at a distal or lower end thereof sometimes damage the insulator
106
. Such damage is often accompanied by the insertion of the bolt
103
.
Once the insulator
106
is damaged, the insulator
106
at such a damaged portion thereof is deficient in insulating performance. Then, the stray current corrosion undesirably occurs thereat.
In
FIG. 13B
, when the bolt
103
is brought into threaded engagement with the magnesium alloy member
101
through a washer
107
, then the washer
107
is rotated in union with the revolving bolt
103
. The rotated washer
107
may damage the insulator
106
, thereby promoting the stray current corrosion at such a damaged location.
Thus, the stray current corrosion is likely to occur, even at the magnesium alloy member
101
having the insulator
106
disposed thereon.
SUMMARY OF THE INVENTION
In view of the above, an object of the present invention is to provide a stray current corrosion-free or stray current corrosion-resistant bolting structure for a magnesium alloy member covered with an insulator.
In order to achieve the above object, the invention provides a bolting structure for a magnesium alloy member, having a non-magnesium alloy and conventional member disposed on the magnesium alloy member, the magnesium alloy member being covered with an insulator, and a bolt initially inserted through the magnesium alloy member and then into the conventional member, thereby permitting the conventional member and the magnesium alloy member to be bolted together, comprising: a washer disposed between a head of the bolt and the magnesium alloy member; and, a lateral washer displacement-proof member for preventing the washer from being laterally displaced, the lateral washer displacement-proof member being positioned either on one of the washer and the magnesium alloy member or between the washer and the magnesium alloy member, wherein the magnesium alloy member is formed with a through-hole that is greater in diameter than a bolthole of the washer.
The lateral washer displacement-proof member prevents lateral displacement of the washer mounted on the magnesium alloy member, and thereby holds the washer in desirable position. The bolt is inserted into the magnesium alloy member by being guided by the bolthole of the washer. The bolt at a distal end thereof is not likely to contact the through-hole of the magnesium alloy member because the through-hole is sufficiently greater than the bolthole. As a result, the insulator remains intact because of non-contact of the bolt with the through-hole, and no stray current corrosion occurs.
In addition, the invention provides a bolting structure for a magnesium alloy member, wherein the through-hole is any non-circular hole, including a polygonal hole, designed to lock the washer against rotation.
Since the washer rotated jointly with the bolt scratches the insulator, a member is provided for locking the washer against rotation in order to prevent the occurrence of scratches and stray current corrosion.
Further, the invention provides a bolting structure for a magnesium alloy member, wherein the lateral washer displacement-proof member is one of a boss, a cylindrical concave, and at least three protrusions, the boss being formed integrally on the washer, the boss having an outer diameter slightly smaller than a diameter of the throughhole, the cylindrical concave having a diameter slightly greater than an outer diameter of the washer, the cylindrical concave being formed in the magnesium alloy member, and the protrusions projecting outward from the magnesium alloy member in order to prevent sideward displacement of the washer. The terms “slightly smaller” and “slightly greater” as previously mentioned take account of a clearance required for conveniently assembling components together.
The boss integrally formed on the washer is engaged with the through-hole, thereby holding the washer in position, which otherwise would be moved sideward. Alternatively, the engagement of the washer with the cylindrical concave holds the washer in position, which otherwise would be displaced sideward. Furthermore, the plurality of protrusions disposed about the washer holds the washer in position, which otherwise would be displaced sideward. That is, these lateral washer displacement-proof members are applied to prevent the washer from being moved sideward or making a gap.
The invention provides a bolting structure for a magnesium alloy member, wherein the washer is affixed to the magnesium alloy member through a double-side adhesive tape.
Such a construction in which the washer is secured to the magnesium alloy member by means of the adhesive tape holds the washer in position, which otherwise would be dislodged from the magnesium alloy member, locks the washer against rotation, and provides enhanced insulating performance of the magnesium alloy member.
Furthermore, the invention provides a bolting structure for a magnesium alloy member, wherein the lateral washer displacement-proof member is a double-side adhesive tape for affixing the washer to the magnesium alloy member.
Such a construction in which the washer secured to the magnesium alloy member by means of the adhesive tape holds the washer in position, which otherwise would result in lateral displacement, rotation, and dislodgement from the magnesium alloy member.
REFERENCES:
patent: 3072423 (1963-01-01), Charlton
patent: 3171518 (1965-03-01), Bergmann
patent: 5147151 (1992-09-01), Hipkins, Jr.
patent: 5584628 (1996-12-01), Bernoni
patent: 5906463 (1999-05-01), Damm et al.
patent: 44-7460 (1944-03-01), None
patent: 58-196312 (1983-11-01), None
patent: 5-52206 (1993-03-01), None
patent: 5-302614 (1993-11-01), None
Ando Katsutoshi
Inaba Yoichiro
Kitayama Ken-ichi
Kusumoto Kozo
Suzuki Eiji
Arent Fox Kintner & Plotkin & Kahn, PLLC
Honda Giken Kogyo Kabushiki Kaisha
Wilson Neill
LandOfFree
Bolting structure for magnesium alloy member does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bolting structure for magnesium alloy member, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bolting structure for magnesium alloy member will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3130107