U.S. patent application number 10/732269 was filed with the patent office on 2004-07-22 for method of connecting and structure of connecting electric wire and connection terminal.
This patent application is currently assigned to YAZAKI CORPORATION. Invention is credited to Asakura, Nobuyuki, Fujimoto, Kei, Onuma, Masanori.
Application Number | 20040142607 10/732269 |
Document ID | / |
Family ID | 32708087 |
Filed Date | 2004-07-22 |
United States Patent
Application |
20040142607 |
Kind Code |
A1 |
Asakura, Nobuyuki ; et
al. |
July 22, 2004 |
Method of connecting and structure of connecting electric wire and
connection terminal
Abstract
After bringing a conductor of an electric wire into press
contact to connect with a wire caulking portion of a connection
terminal, the conductor and the wire caulking portion are welded to
connect by irradiating laser beam to a bottom wall of the wire
caulking portion. Laser irradiation is carried out intermittently
by three times and the laser irradiation at the second time and
thereafter which is carried out later is carried out such that
during a time period in which a laser welded portion immediately
previously is brought into a predetermined state of elevating
temperature, portions or welded regions overlap welded regions in
laser irradiation irradiated previously.
Inventors: |
Asakura, Nobuyuki;
(Shizuoka, JP) ; Fujimoto, Kei; (Shizuoka, JP)
; Onuma, Masanori; (Shizuoka, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
YAZAKI CORPORATION
|
Family ID: |
32708087 |
Appl. No.: |
10/732269 |
Filed: |
December 11, 2003 |
Current U.S.
Class: |
439/877 |
Current CPC
Class: |
H01R 4/185 20130101;
Y10T 29/49185 20150115; H01R 43/0221 20130101; Y10T 29/49179
20150115 |
Class at
Publication: |
439/877 |
International
Class: |
H01R 004/10 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 11, 2002 |
JP |
P2002-359486 |
Claims
What is claimed is:
1. A method of connecting an electric wire and a connection
terminal comprising the steps of; crimping a conductor of the
electric wire with a wire caulking portion of the connection
terminal; subsequently performing at least two times of irradiating
a laser beam to the wire caulking portion for laser welding;
wherein a second laser irradiation is carried out subsequently to a
first laser irradiation within a predetermined time period in which
a laser welded portion welded in the first laser irradiation is
brought into a predetermined state of elevating a temperature, and
a second welded region on which the second laser irradiation is
carried out overlaps at least partially a first welded region on
which the first laser irradiation is carried out.
2. A method of connecting an electric wire and a connection
terminal according to claim 1, wherein the time period is set not
larger than 2 seconds.
3. A method of connecting an electric wire and a connection
terminal according to claim 1, wherein the connection terminal is
made of a Cu alloy and the conductor is made of an aluminum series
or Fe--Ni series metal.
4. A method of connecting an electric wire and a connection
terminal according to claim 1, wherein the connection terminal is
made of an aluminum species material or a stainless steel species
material.
5. A structure of connecting an electric wire and a connection
terminal wherein a conductor of the electric wire is brought into
press contact with a wire caulking portion of the connection
terminal is welded to the wire caulking portion by laser welding at
two portions or more thereof and welded regions overlap each other
at least partially.
6. A structure of connecting an electric wire and a connection
terminal according to claim 5, wherein the connection terminal is
made of a Cu alloy and the conductor is made of an aluminum series
or Fe--Ni series metal.
7. A structure of connecting an electric wire and a connection
terminal according to claim 5, wherein the connection terminal is
made of an aluminum species material or a stainless steel species
material.
Description
[0001] The present application is based on Japanese Patent
Application No. 2002-359486, the entire contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method of connecting and
a structure of connecting an electric wire and a connection
terminal for bringing a conductor of an electric wire into press
contact to connect with a wire caulking portion of a connection
terminal and thereafter welding to connect the conductor and the
connection terminal by laser welding.
[0004] 2. Related Art
[0005] Conventionally, as a method of connecting an electric wire
and a connection terminal, there is spread a method of electrically
connecting an electric wire and a connection terminal by bringing a
wire caulking portion mounted to the connection terminal into press
contact to connect to caulk on a conductor of the electric
wire.
[0006] However, in the case of a press contact connection, when the
conductor of the electric wire is constituted by a multicore
twisted wires structure, although core wires disposed on an outer
peripheral side thereof are brought into direct contact with the
connection terminal and therefore, conduction is easy to achieve,
core wires disposed on a center side thereof is brought into
contact with the connection terminal via the core wires on the
outer peripheral side.
[0007] Further, when dimensions of C/W and C/H of a press contact
terminal 1 do not match as shown by FIG. 5, a clearance 5 is liable
to be produced between a conductor press contact portion la and a
conductor 3, which is devoid of reliability of electric connection.
Therefore, there poses a problem that many kinds of press contact
terminals having dimensions of C/W and C/H matched to respective
sizes of electric wires and respective kinds of terminals need to
prepare and caulking operation needs to control to thereby increase
fabrication cost.
[0008] Hence, in order to prevent contact resistance at a press
contact portion from being dispersed, as shown by FIG. 6, there has
been proposed a connecting method of bringing the conductor 3 of an
electric wire 2 into press contact to connect with the conductor
press contact portion la of the connection terminal 1 and
thereafter irradiating laser beam 9 from a laser generating
apparatus 8 to the conductor 3 exposed at the center portion and
the front and rear portions of an upper face of the conductor press
contact portion la to thereby weld the conductor press contact
portion la and the conductor 3 (for example, refer to
JP-A-2-103876).
[0009] However, according to the above-described connecting method,
as shown by FIG. 7, there poses a problem that a terminal material
melted by irradiating the laser beam 9 is absorbed by clearances of
the conductor 3 and a large recess 13 is produced at a laser welded
portion 11 to thereby reduce welding strength or the like. Further,
in laser welding, the welding is carried out by irradiating the
laser beam having high density energy and therefore, rapid heating
or rapid boiling of the terminal material and the conductor is
brought about which may bring about explosive scattering (splash
phenomenon).
[0010] Hence, there has been proposed a laser welding terminal in
which a wire caulking portion of a connection terminal is provided
with a projected portion or a thick-walled portion for replenishing
a melted volume and a recess produced by irradiating laser beam is
filled by the melted projected portion or the melted thick-walled
portion (for example, refer to JP-A-6-302341).
[0011] Further, as shown by FIG. 8, there has been proposed a
structure of a connecting portion in which there is formed an
irradiation port 17 for irradiating laser beam at a pair of core
line press contact pieces 16, 16 formed at a press contact portion
15 of a connection terminal 14 and respective strands of the core
line portion 3 are subjected to laser welding by irradiating laser
directly to the core line portion 3 at inside of the press contact
portion 15 by passing the irradiation port 17 (for example, refer
to JP-A-2000-231944).
[0012] According thereto, even when the connection terminal is
brought into press contact therewith without previously operating
excessive press contact force to a portion of core lines which are
not welded, respective strands can be welded together at inside of
the press contact portion, and electric resistance between the
connection terminal and the electric wire can be restrained to
reduce by restraining to reduce contact resistance among the
respective strands.
[0013] However, when the electric wire and the connection terminal
are connected by laser welding described in JP-A-6-302341 and
JP-A-2000-231944, mentioned above, and the like, as described
above, the projected portion or the thick-walled portion for
replenishing the welded volume needs to provide at the wire
caulking portion of the connection terminal, or the irradiation
port for irradiating laser beam needs to form at inside of the
press contact portion of the connection terminal to thereby pose a
problem of increasing working steps in fabricating the connection
terminal or increasing cost of the connection terminal owing to
complicated formation of a die for pressing a connection
terminal.
[0014] Further, in recent times, there are a number of cases in
which materials (physical properties) of a connection terminal and
an electric wire differ from each other. For example, although Cu
alloys are frequently used for the material of the connection
terminal, in contrast thereto, a material which is difficult to
achieve electric conduction of aluminum series or Fe--Ni series or
the like is frequently used for the material of the electric wire.
Whereas a melting point and heat of melting of aluminum are
660.degree. C. and 94.5 cal/g, and a melting point and heat of
melting of copper are 1083.degree. C. and 50.6 cal/g and physical
properties thereof differ from each other significantly and
therefore, it is difficult to ensure excellent connection function
by applying laser welding, mentioned above.
SUMMARY OF THE INVENTION
[0015] An object of the invention relates to resolving the
above-described problem and provides an excellent method of
connecting and an excellent structure of connecting an electric
wire and a connection terminal capable of stably ensuring an
electric resistance and a mechanical strength of the connection
terminal and the electric wire without increasing cost of the
connection terminal.
[0016] The above-described object of the invention is achieved by a
method of connecting an electric wire and a connection terminal
characterized in that a conductor of an electric wire is brought
into press contact to connect with a wire caulking portion of a
connection terminal, thereafter, laser irradiation for welding to
connect the conductor and the wire caulking portion by irradiating
a laser beam to the wire caulking portion is carried out at least
two times or more and the laser irradiation which is carried out
later is carried out such that within a time period in which a
laser welded portion welded previously is brought into a
predetermined state of elevating a temperature, a portion of a
welded region thereof overlaps the welded region in laser
irradiation welded previously as described.
[0017] Further, the above-described object of the invention is
achieved by a structure of connecting an electric wire and a
connection terminal characterized in that a conductor of an
electric wire brought into press contact to connect with a wire
caulking portion of a connection terminal is welded to the wire
caulking portion by a laser at two portions or more thereof and
portions of welded regions at respective times of welding by the
laser overlap each other.
[0018] According to the method of connecting and the structure of
connecting the electric wire and the connection terminal having the
above-described constitution, the connection terminal and the
electric wire are welded to connect by irradiating the laser beam
from above the wire caulking portion of the connection terminal, a
metallic bonding portion is formed between the connection terminal
and the electric wire and. therefore, the electric resistance and
the mechanical strength can stably be ensured.
[0019] Further, at a laser beam irradiated portion at the first
time, rapid boiling is brought about by rapid heating by
irradiating the laser beam and explosive scattering can be brought
about at the wire caulking portion.
[0020] However, laser beam irradiated portions at the second time
and thereafter are set such that a welded region thereof overlaps a
welded portion of the laser beam irradiated portion immediately
previously, laser irradiation is carried out within a time period
in which a state of elevating a temperature by irradiating the
laser beam immediately previously remains and therefore, rapid
heating is not constituted by heating by irradiating laser beam at
the second time and thereafter, the material is gradually melted
and therefore, explosive scattering caused by rapid boiling can be
prevented from being brought about.
[0021] Further, even when a recess or a cavity is formed by
explosive scattering in the irradiating laser beam at the first
time, a material which is melted gradually flows into the recess or
the cavity to fill in irradiating the laser beam at the second time
and therefore, the recess or the cavity does not remain in the
laser welded portion.
[0022] Hence, even when materials (physical properties) of the
connection terminal and the electric wire differ from each other
and laser beam having a high density energy matched to a material
having large heat of melting needs to be irradiated, a stable
welded state can be achieved by preventing explosive scattering
from being brought about and an excellent connected state between
the connection terminal and the electric wire conductor can be
maintained over a long period of time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is aside view for explaining a method of connecting
and electric wire and a connection terminal according to an
embodiment of the invention.
[0024] FIG. 2 is a cross-sectional view of an essential portion of
FIG. 1.
[0025] FIGS. 3A to 3C illustrate sectional views enlarging an
essential portion showing a state of welding the electric wire and
the connection terminal according to the embodiment.
[0026] FIG. 4 is a graph showing a result of a durability test.
[0027] FIG. 5 is a cross-sectional view for explaining a problem of
a conventional press contact terminal.
[0028] FIG. 6 is a perspective view for explaining a method of
connecting an electric wire and a connection terminal by
conventional laser welding.
[0029] FIG. 7 is a cross-sectional view for explaining a problem of
a connecting method shown in FIG. 6.
[0030] FIG. 8 is a perspective view for explaining a method of
connecting an electric wire and a connection terminal by other
conventional laser welding.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] A detailed explanation will be given of a method of
connecting and a structure of connecting an electric wire and a
connection terminal according to an embodiment of the invention in
reference to the attached drawings as follows.
[0032] As shown by FIG. 1 and FIG. 2, according to a method of
connecting an electric wire 25 and a connection terminal 21, after
bringing a conductor 26 of the electric wire 25 into press contact
to connect with a wire caulking portion 23 of the connection
terminal 21, the conductor 26 and the wire caulking portion 23 are
welded to connect by irradiating laser beam 28 to a bottom wall 23a
of the wire caulking portion 23.
[0033] In this case, the laser irradiation is carried out
intermittently by three times and laser irradiation at the second
time and thereafter which is carried out later is carried out such
that within a time period (within a short time period of about 2
seconds) in which a laser welded portion immediately previously is
brought into a predetermined elevated temperature state such that a
portion of a welded region at the second time and thereafter
overlaps a welded region in laser irradiation immediately
previously.
[0034] According to the embodiment, the laser welded portion is set
to the bottom wall 23a of the wire caulking portion 23 which is not
deformed in press contact connection and the laser beam 28 is
irradiated from an outer side of the bottom wall 23a.
[0035] As shown by FIG. 2, respective laser irradiated portions are
disposed substantially on a center line in a width direction of the
bottom wall 23a and a welding at the first time, welding at the
second time and welding at the third time are carried out by
shifting positions thereof successively along a longitudinal
direction of the electric wire 25.
[0036] FIGS. 3A to 3C illustrate sectional views enlarging an
essential portion showing a state of welding the electric wire 25
and the connection terminal 21 according to the embodiment, FIG. 3A
shows a welded region Y1 by the welding at the first time, FIG. 3B
shows welded regions Y1 and Y2 by the respective weldings at the
first time and the second time and FIG. 3C shows welded regions Y1,
Y2 and Y3 by the respective weldings at the first time, the second
time and the third time.
[0037] That is, according to the above-described method of
connecting the electric wire 25 and the connection terminal 21
according to the embodiment, three times of laser irradiation is
carried out such that portions of the respective welded regions Y1,
Y2 and Y3 by irradiating laser beam overlap each other and at the
first laser beam irradiated portion, heating by irradiating laser
beam constitutes rapid heating and the explosive scattering of the
material of the wire caulking portion 23 which is rapidly boiled
can be brought about. A portion of the welded region Y1 shown in
FIG. 3A designated by notation K is a cavity constituting a defect
by explosive scattering.
[0038] However, at the laser beam irradiated portion at the second
time and thereafter, laser irradiation is carried out within a time
period in which a state of elevating temperature by irradiating
laser beam immediately previously remains and therefore, heating by
irradiating laser beam at the second time and the third time does
not constitute rapid heating, the material of the wire caulking
portion 23 is gradually melted and therefore, as shown by FIG. 3B
and FIG. 3C, explosive scattering caused by rapid boiling can be
prevented from being brought about.
[0039] Further, the material which is gradually melted in
irradiating laser beam at the second time flows into the cavity K
formed by explosive scattering in irradiating laser beam at the
first time to fill the cavity K as shown by FIG. 3B and therefore,
the cavity K does not remain at the laser welded portion.
[0040] Hence, even when materials (physical properties) of the
connection terminal 21 and the conductor 26 to be welded differ
from each other (for example, when the connection terminal 21 is
made of a Cu alloy and the conductor 26 is made of an aluminum
series or Fe--Ni series metal), a stable welded state can be
achieved by preventing explosive scattering from being brought
about.
[0041] That is, when the conductor 26 made of the aluminum series
metal and the connection terminal 21 made of the Cu alloy are
welded, laser beam having high density energy matching to the
aluminum series conductor 26 having the large heat of melting needs
to irradiate to the connection terminal 21 made of the Cu alloy,
however, as described above, according to the connecting method of
the embodiment, explosive scattering of the connection terminal 21
can be restrained and stable state of welding the connection
terminal 21 and the conductor 26 can be achieved.
[0042] Therefore, according to the method of connecting and the
structure of connecting the electric wire 25 and the connection
terminal 21 in the embodiment, even when the materials of the
connection terminal 21 and the conductor 26 differ from each other,
the explosive scattering phenomenon of the melted material caused
by rapid boiling of the material by irradiating laser beam is
restrained, and the metallic bonded portion (integrated portion by
alloying) of the connection terminal 21 and the conductor 26 is
formed by laser welding and therefore, the electric resistance and
the mechanical strength of the welded portion can stably be ensured
and an excellent connected state between the connection terminal 21
and the conductor 26 can be maintained over a long period of
time.
[0043] Further, laser beam is irradiated directly from above the
wire caulking portion 23 of the connection terminal 21 and
therefore, the connection terminal 21 needs not to be mounted with
a special structure of a projected portion or a thick-walled
portion or an irradiation port or the like for laser welding.
[0044] Further, according to the embodiment, the laser beam
irradiated portion is set to the bottom wall 23a of the wire
caulking portion 23 which is difficult to deform in press contact
connection of the connection terminal 21 and therefore, working
accuracy of the electric wire working portion 23 to be caulked does
not effect influence on laser welding and there is not needed high
accuracy formation of dimension of C/W and C/H of the wire caulking
portion 23 bringing about a reduction in yield of the press contact
processing.
[0045] Therefore, the electric resistance and the mechanical
strength of the connection terminal 21 and the electric wire 25 can
stably be ensured without increasing cost of the connection
terminal 21.
[0046] Further, according to the embodiment, the portions of the
connection terminal 21 welded to the wire caulking portion 23 by
laser are constituted by three locations, the laser welded portions
can arbitrarily set so far as the laser welded portions are
constituted by two portions or more. The number of the laser-welded
portions may pertinently be controlled in accordance with the size
of the terminal 21, the sectional area of the conductor 26,
required mechanical connection strength or the like.
[0047] Further, a degree of overlapping (amount of overlapping) of
the welded regions shown in FIG. 3B and FIG. 3C may pertinently be
controlled such that welding of the connection terminal 21 and the
conductor 26 becomes proper in consideration of a difference
between melting temperatures caused by the materials of the
conductor 26 and the connection terminal 21 and the like.
[0048] Further, an aluminum species material or a stainless steel
species material may be used for the material of the connection
terminal 21 such that the physical property becomes proximate to
the physical property of the melting point or the like of the
conductor 26 of the aluminum species.
[0049] Thereby, the function of connecting the connection terminal
21 and the conductor 26 is further promoted.
EXAMPLES
[0050] Next, a connection terminal according to the invention
(Embodiment), which is connected with a conductor of an electric
wire by crimping and subsequently performing three times of laser
irradiation as described above, and a connection terminal
(Comparative Example), which is connected with a conductor of an
electric wire only by crimping in the same manner as Embodiment and
no laser irradiation is conducted, are subjected to two durability
tests. The comparison in performance of the connection terminals at
the initial states and after subjected the durability tests
(Durability Test 1 and Durability Test 2) respectively is
illustrated in a graph of FIG. 4.
[0051] Further, a Cu alloy is used for the respective connection
terminals and an aluminum series conductor is used for the
respective conductors.
[0052] In this case, Durability Test 1 is a high temperature
leaving test for leaving samples (10 pieces respectively) in a high
temperature environment at 120.degree. C. for 120 hours and
resistances of the respective samples after having been left are
measured and an average value thereof is illustrated.
[0053] Further, Durability Test 2 is a thermal shock test for
leaving samples (10 pieces respectively) in an environment
repeating an environment of -40.degree. C. and an environment of
120.degree. C. and after repeating by 200 cycles, resistances of
the respective samples are measured and an average value thereof is
illustrated.
[0054] As is apparent from the graph of FIG. 4, although there is
not a change in the high temperature leaving test (Durability Test
1) both in the embodiment and the comparative example, a large
difference is observed therebetween in the thermal shock test
(Durability Test 2).
[0055] This is because whereas according to the comparative example
of mechanically bringing foreign metals into press contact with
each other, the respective metals are elongated and contracted by a
change in temperature and contact points are moved at an interface
therebetween, in coupling the foreign metals welded by laser
according to the embodiment, the foreign metals are alloyed to
integrate and therefore, even when the foreign metals are elongated
or contacted by a difference in temperatures, a total of the alloy
is elongated and contracted which has nothing to do with the
coupling. Therefore, there is not a change in the resistance of the
connection terminal according to the embodiment.
[0056] According to the method of connecting and the structure of
connecting the electric wire and the connection terminal of the
invention, a connection terminal and an electric wire are welded to
connect by irradiating laser beam from above the wire caulking
portion of the connection terminal, the metallic bonding portion is
formed between the connection terminal and the electric wire and
therefore, the electric resistance and the mechanical strength can
stably be ensured.
[0057] Further, although at the first laser beam irradiated
portion, rapid boiling is brought about by rapid heating by
irradiating laser beam and explosive scattering can be brought
about at the wire caulking portion, however, the laser beam
irradiated portions at the second time and thereafter are set such
that the welded regions overlap both of the laser beam irradiated
portions immediately previously, laser beam is irradiated within
the time period in which the state of elevating temperature by
irradiating laser beam immediately previously remains and
therefore, heating by irradiating laser beam at the second time and
thereafter does not constitute rapid heating but the materials are
melted gradually and therefore, explosive scattering caused by
rapid boiling can be prevented from being brought about.
[0058] Further, even when the recess or the cavity is formed by
explosive scattering in irradiating laser beam at the first time,
the melted material flows into the recess portion or the cavity to
fill in irradiating laser beam at the second time and therefore,
the recess or the cavity does not remain at the laser welded
portion.
[0059] Hence, even when the materials of the connection terminal
and the electric wire differ from each other and laser beam having
high density energy matched to a material having large heat of
melting needs to irradiate, a stable welded state can be achieved
by preventing explosive scattering from being brought about and an
excellent connected state between the connection terminal and the
electric wire conductor can be maintained over a long period of
time.
[0060] Therefore, there can be provided the excellent method of
connecting and the excellent structure of connecting the electric
wire and the connection terminal capable of stably ensuring the
electric resistance and the mechanical strength of the connection
terminal and the electric wire without increasing cost of the
connection terminal.
* * * * *