BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to electrical connectors
and, more particularly, to filtered electrical connectors providing EMI protection.
2. Prior Art
U.S. Patent 5,489,220
discloses a filter connector with a ferrite barrel for two electrical
U.S. Patent No. 5,241,910
European Patent Application No. EP 0 512 682
disclose a connector including a ferrite bead having two holes in spaced
relation with an electric terminal disposed in each hole for making electrical contact
with an associated one of the protruding pins of a pin type electric squib. This
connector may be an angled connector. Moreover,
U.S. Patent 5,213,522
discloses a filtered connector with a multipiece ferrite block. A problem
with these types of ferrite blocks or beads is that they must be made of electrically
non-conductive ferrite oxide to prevent short-circuiting of the contacts and, therefore,
cannot filter lower frequencies (about 1-150 MHz) without increasing length of the
ferrite block and thereby increasing the size of the connector. For a filtered connector
intended to be used in a small space, such as an air bag connector, increasing the
size of the connector is not desired. If an electrically conductive ferrite oxide
material needed to be used for lower frequency attenuation, such as about 1-150
MHz, electrical insulators would need to be added between the contacts and the ferrite
DE 43 10 369
discloses an angled air bag connector including an RF coil for EMI filtering.
A connector of this type is illustrated in Figs. 8 and 9 of the drawings. The connector
100 is an angled connector including a main portion 101 comprising conductor terminals
102, 103 for connecting respective input conductors or lead wires 104, 105, and
a contact portion 106 comprising connector terminals 107, 108 for receiving contact
pins of a mating connector of the air bag assembly (not shown). The RF coil 109
is connected in a series circuit with one of the input conductors or lead wires
104 to one of the connector terminals 108. The RF coil 109 may be wrapped around
a cylindrical ferrite body 110. The RF coil 109 is disposed in a transverse direction
with respect to the connector terminals 107, 108 and conductor terminals 102, 103
adjacent to the 90° bend of the angled connector. In this way, the main portion
101 of the connector extends beyond the contact portion 106 forming a coil portion
111 so that the connector may be considered as being generally T-shaped. Thus, the
RF coil, and the ferrite body, if any, increase the size of the connector in longitudinal
Coils have demanding packaging space requirements and are
a limiting factor in further miniaturization of filtered interconnections. Coil
performance is targeting a limited frequency range, and improved performance at
higher frequency ranges is desired.
Moreover, prior art air bag connectors comprise two locking
latches on opposite sides of the connector so as to lock the connector to the socket
provided on the igniter of the air bag module. Having the locking latches provided
on the sides of the connector inhibits close side-by-side packaging of two or more
WO-A-9 908 062
discloses a device according to the preamble of claim 1.
SUMMARY OF THE INVENTION
According to the present invention, there is provided an
EMI filter connector device comprising a first contact element, a tubular ferrite
bead surrounding said first contact element, and a coil wound around said ferrite
bead. Preferably, the coil has a first coil terminal and a second coil terminal,
and said connector device further comprises a first conductor connecting portion,
wherein one of said first and second coil terminals is connected to said first contact
element, and wherein the other of said first and second coil terminals is connected
to said first conductor connecting portion.
Preferably, the connector comprises a second contact element
and a second conductor connecting portion wherein said second contact element is
connected to said second conductor connecting portion. In a preferred embodiment
said first and second contact elements are female contacts.
It is preferred that the connector of the present invention
comprises a housing having a main portion and a contact portion, said contact portion
being adapted to be inserted into an associated socket and extending at about 90°
with respect to said main portion so as to provide an angled connector wherein said
contact elements, said ferrite bead, and said coil are disposed in said contact
portion of said housing.
The new EMI filtering connector of the present invention
provides connector miniaturization with improved performance over an extended frequency
range as compared to coil only.
The design of the present invention compiles EMI protection
of two formerly separated filtering devices (coil and ferrite beads) in one optimal
packaging. It consists of a coil wound around a cylindrical tubular ferrite bead
and welded at one end to the terminal receptacle fed through the ferrite bead. The
signal is routed through the coil and then through the ferrite bead providing added
filtering effect. The design provides further performance improvement and significant
reduction of the packaging size. The filtering system of the present invention comprising
one coil and ferrite bead EMI protective device has a superior performance and efficiency
in the 100 to 300 MHz range and at least 20dB attenuation over a frequency range
from 1 MHz to 1.5 GHz with appropriate selection of the ferrite material. Performance
can be tailored by adding more filtering devices per circuit (combinations of coil
and ferrite bead filtering units and ferrite bead filtering units). The use of the
filtering system may well be expanded to a frequency of 3.0 GHz and beyond.
This design provides minimum packaging size for required
electrical and mechanical performance. The filter consisting of a coil and a ferrite
bead is packaged in the contact portion (or nozzle area) of the connector, eliminating
the necessity of packaging space in the connector housing.
The present invention provides good filtering performance
of the coil within optimized packaging, and in addition thereto, due to the unique
double signal routing, the coil performance is supplemented by the ferrite bead
performance. The ferrite bead is used as the coil core or bobbin to enhance magnetic
permeability. By adding this new function as a coil core or bobbin to the ferrite
bead, the present invention uses both filters (coil and ferrite bead) in series
to maximize performance to the ultimate level within optimal packaging. The present
invention further provides flexibility of tailoring or calibrating the filtering
performance by changing the number of coil windings and/or the material and/or shape
of the ferrite bead.
The present invention offers ultimate filtering performance
base on unique signal routing provided in this coil filtered terminal package solution.
The present invention improves the role of the ferrite core and adds it as an additional
inductive filter in series with the coil.
Providing only one locking hook or locking leg improves
side-to-side packaging performance for serviceable connectors and provides more
reliable locking. The housing (nozzle) is premolded and the filter and terminal/wire
assembly is preassembled. Low pressure over-molding is used to enclose the components
in the housing. Side-to-side packaging is an important point e. g. for dual stage
air bag systems.
The present invention provides a miniaturized connector
that is about three times smaller than the current DC air bag connectors with side-to-side
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing aspects and other features of the present
invention are explained in the following description, taken in connection with the
accompanying drawings, wherein:
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
- Fig. 1
- is an exploded view of the EMI protective system included in an electrical connector
of the present invention;
- Fig. 2
- is perspective view of the EMI protective system shown in Fig. 1 in an assembled
- Fig. 3
- is a circuit diagram of the electric scheme including the electrical connector
of the present invention and an associated igniter or squib;
- Fig. 4
- is a partially cut perspective view of an embodiment of an electrical connector
according to the present invention;
- Fig. 5
- is a perspective view of another embodiment of an electrical connector according
to the present invention with the cover of the housing removed;
- Fig. 6
- is a perspective view of the electrical connector of Fig. 5 including the cover
of the housing;
- Fig. 7
- is a perspective view of a side-by-side arrangement of two electrical connectors
in accordance with the present invention;
- Fig. 8
- is a schematic top plan view of a prior art connector;
- Fig. 9
- is a schematic side view of the prior art connector shown in Fig. 8;
- Fig. 10
- is a perspective view of a preferred embodiment of the EMI protective system
of the present invention;
- Fig. 11
- is a perspective view of a terminal of the EMI protective system of Fig. 10
- Fig. 12
- is one embodiment of a ferrite bead which may be used in the EMI protective
system of the present invention;
- Fig. 13
- is another embodiment of a ferrite bead which may be used in the EMI protective
system of the present invention; and
- Fig. 14
- is yet another embodiment of a ferrite bead which may be used in the EMI protective
system of the present invention.
Referring to Fig. 1, there is shown an exploded view of
the EMI protective system included in an electrical incorporating features of the
present invention. Although the present invention will be described with reference
to the embodiments shown in the drawings, it should be understood that the present
invention can be embodied in many alternate forms of embodiments. In addition, any
suitable size, shape or type of elements or materials could be used.
The EMI protective system may be used in a connector connecting
electrical conductors with an air bag gas generator. However, the connector could
be used to connect conductors with other devices. Referring also to Fig. 2, the
EMI protective system generally comprises a ferrite bead or hood 1 and a coil 2
wound around the ferrite bead 1.
Preferably, the ferrite bead 1 is comprised of metal powder
which is pressed into a mold and sintered into shape. Alternative manufacturing
such as extrusion could also be used.
The ferrite bead 1 has a generally tubular cylindrical
shape and forms a sleeve for accommodating a female contact element 3 which is commonly
comprised in the electrical connector. In a preferred embodiment, the ferrite bead
1 has a tubular shape with an inner diameter of about 1.5 mm and an outer diameter
of about 2.5 mm. Other sizes are available for different sizes of the contact element.
At least one and normally two contact pins or male contacts
4 are commonly associated with the igniter or squib (not shown) and project therefrom.
For the sake of simplicity, only one such contact pin is shown in Figs. 1 and 2.
In the assembled condition, as shown in Fig. 2, the contact pin 4 is inserted into
the female contact 3 of the connector. Both the contact pin 4 and the female contact
3 extend into the ferrite bead 1 such that contact between the female and the male
contacts is made within the ferrite bead 1. Preferably, there is a friction fit
between the female contact 3 and the ferrite bead 1 when the contact 3 is inserted
into the ferrite bead 1. The ferrite bead 1 may be made of non-conductive ferrite
or, if particular filter properties of conductive ferrite are preferred, it may
be made of conductive ferrite.
The coil 2 has two terminals 2a and 2b. In a preferred
embodiment, terminal 2a at the end of the coil 2 adjacent to the female contact
3 is used for signal input, i. e. it is connected to a conductor 5 to be connected
to the contact pin 4, such as a conductor providing a firing or deployment signal
for an associated air bag. The terminal 2b at the opposite end of the coil 2 adjacent
to the contact pin 4 is electrically connected to a portion or tab 3a of the female
contact 3 by welding, soldering, or other suitable means. Of course, the terminals
2a, 2b of the coil 2 may be connected in the opposite sense, i. e. vice versa to
the above configuration.
Fig. 3 is a circuit diagram of the electric scheme including
the electrical connector of the present invention and an associated igniter or squib.
The circuit diagram shows a series circuit of signal input 6, e. g. from vehicle
electronics providing a firing or deployment signal for the associated air bag,
to signal output 7, e. g. connected to ground. Signal input 6 and signal output
7 may be considered as two conductors or wires in a lead or cable from vehicle electronics
to the air bag connector. The series circuit comprises the coil 2, the ferrite bead
1, and a resistor 8 inside the igniter, with reference numeral 9 denoting the welding
point of terminal 2b to the female contact portion 3a, and reference numerals 10
and 11 denoting the contact points of the female contact 3 with contact pin 4, and
the contact point of another contact pin (not shown in Figs. 1 and 2) with another
contact pin (not shown in Figs. 1 and 2), respectively. The resistor 8 inside the
igniter is usually a wire which heated by a deployment signal so as to cause ignition
of the igniter or squib.
Fig. 4 shows an embodiment of an electrical connector 12
according to the present invention wherein coil 2 is connected in an opposite sense
to that in the embodiments of Figs. 1 and 2. The connector 12 is an angled connector
and comprises generally two portions, a conductor portion or main portion 12a and
a contact portion or nozzle 12b.
The electrical components of the connector 12 are accommodated
in a housing 13. The housing 13 may be made of dielectric plastic and comprises
two separate receiving areas 14, and two holes 15 through a bottom face 16 of the
housing into the receiving areas 14. The contact portion 12b is adapted to be plugged
e. g. into a socket of an igniter for a gas generator (not shown).
The connector 12 preferably comprises two electrical contacts,
each comprising a female contact and a connection area for connection to electrical
conductors. Preferably, the female contacts are comprised of stamped and formed
sheet metal. The female contacts, one of which is shown at 3, each have two spring
contact arms for making safe contact with a contact pin.
In this embodiment the connector 12 has a 90° bend
for a right angle connector. However, the connector 12 could be straight for an
The socket of the igniter (not shown) has two male pin
contacts (only one of which is shown at 4 in Figs. 1, 2, and 4) at a fixed spacing
relative to each other that are received in the two female contacts through the
holes 15 in the housing 13. Thus, the connector is able to electrically connect
the contact pins to the conductors.
As may be seen in Fig. 5, a preferred alternative embodiment
of the contact element 3 may comprise two tabs 3a, 3b wherein one (3a) of said tabs
is used for contacting a coil terminal if a coil is used with this contact element,
and the other tab 3b being used for connection with a conductor if no coil is used
with this contact element. In this way, only one type of contact element is required
for both filtered and unfiltered contacts.
Figs. 5 and 6 illustrate another important feature of the
present invention. Fig. 5 shows another embodiment of an electrical connector 12
according to the present invention with a cover of the housing 13 removed, while
Fig. 6 is a perspective view of the electrical connector of Fig. 5 including a cover
17. The cover 17 may be over-molded and also provides strain relief for the conductors.
In an alternate embodiment the cover 17 need not be over-molded.
The main portion 12a of the connector 12 has a rear end
18 where the conductors are fed into the connector and a front end 19 near the contact
portion 12b. By placing the filtering components (ferrite bead 1 and coil 2) in
the contact portion 12b of the connector 12 (see above), it is possible to provide
a single locking or latching hook 20 at the front end 19 of an angled connector.
A plurality of such connectors can thus be placed in close
proximity next to each other in a side-by-side relationship, thereby requiring less
space than prior art designs while providing reliable locking of the connector to
an associated socket (see Fig. 7).
In Fig. 7, an alternate embodiment of a connector 12 with
a different single locking hook 20 in the frontal region of the connector is shown.
It is to be understood that instead of a locking hook other locking or latching
means could be used in the frontal region of the connector.
According to the present invention, cost and weight and
size of the connector can be minimized. The present invention allows two different
filter components to be used in the same connector, namely a ferrite bead and a
coil for a better or wider range of filtering. The present invention provides a
means to reduce the size of the connector while maintaining good filtering by providing
a ferrite bead around one contact and by providing a coil would around the ferrite
bead wherein said filtering components are disposed in the contact portion or nozzle
of the connector. This design also enables the use of a single locking hook in the
frontal region of the connector.
Figs. 10 to 14 relate to certain aspects of the invention
which may be of particular importance and advantage for the manufacturing of the
EMI protective system of the present invention. More particularly, Fig. 10 is a
perspective view of a preferred embodiment of the EMI protective system of the present
invention, similar to the embodiment shown in Figs. 1 to 4 and described in connection
therewith. In particular, sizes and materials used for the individual components
may be identical to those described above. Therefore, the same reference numerals
are used to designate similar components.
The EMI protective system shown in Fig. 10 comprises a
ferrite bead or hood 1 and a coil 2 wound around the ferrite bead 1. The ferrite
bead 1 has a generally tubular cylindrical shape and forms a sleeve for accommodating
a female contact element 3 which is commonly comprised in the electrical connector.
The coil 2 has two terminals 2a and 2b. In the embodiment
of Fig. 10, the coil 2 is connected in an opposite sense to that in the embodiments
of Figs. 1 and 2, or identical to the embodiment of Fig. 4. In the embodiment of
Fig. 10, terminal 2b at the distal end of the coil 2 is used for signal input and
is connected to a conductor 5, and terminal 2b at the opposite or proximate end
of the coil 2 is electrically connected to a portion or tab 3a of the female contact
3, preferably by welding.
The conductor 5 is shown to comprise a sheath or insulation
5a and an electrically conducting core 5b which is connected to the terminal 2b
of the coil. In the embodiment of Fig. 10, a separate contact portion 3b is provided
to which the core 5b of the conductor 5 is connected, preferably by welding. While
the separate contact portion 3b is not necessary for proper functioning of the EMI
protective system, provision of such a contact portion 3b facilitates manufacturing
of the system. For example, the core 5b of the conductor and the terminal 2b of
the coil 2 could both be individually welded to the contact portion 3b thus avoiding
the need to directly connect the terminal 2b of the coil 2 to the core 5b of the
conductor which may be difficult or cumbersome. In this case, the contact portion
3b serves as a bridge between the core 5b of the conductor and the terminal 2b of
the coil 2. Alternatively, if the core 5b of the conductor and the terminal 2b of
the coil 2 are directly coupled, such as by welding, either one or both of the core
5b and the terminal 2b could be attached or welded to the contact portion 3b so
as to fix the relative position of connector 5 and terminal 2b which facilitates
assembly of the EMI protective system e. g. in an electrical connector.
As has been explained above with reference to Fig. 3, the
signal is routed first through the coil 2, then back to the tab 3a of the female
contact 3 and then through the ferrite bead 1.
In Fig. 11, the female contact 3 of the EMI protective
system of Fig. 10 is shown before singulation. This means that the female contact
3 may be manufactured e. g. by stamping and bending of a single piece of sheet metal,
such that it includes the main body of the female contact as well as the tab 3a
and the contact portion 3b. At a later stage, e. g. after the terminals 2a and 2b
are connected to the tab 3a and the contact portion 3b, respectively, a singulation
area 3c between the tab 3a and the contact portion 3b may be severed so as to electrically
and mechanically separate the contact portion 3b from the female contact 3. The
singulation area 3c is preferably a narrow web between the tab 3a and the contact
As can be seen in Fig. 11, the main body of female contact
3 is of a generally barrel-type or tubular configuration so as to be able to receive
a contact pin such as contact pin 4. Preferably, the main body of the female contact
extends at a right angle to the tab 3a and the contact portion 3b. The main body
may comprise some kind of means to engage the contact pin. Such means could be flexible
tongues or webs extending into the interior of the main body, or a friction fit,
press fit, or interference fit of the main body and the contact pin. Alternatively,
the main body of the female contact 3 could be generally cylindrical, and the contact
pin could comprise flexible tongues or the like.
Figs. 12 to 14 show embodiments of a ferrite bead which
may be used in the EMI protective system of the present invention, serving as a
bobbin for the coil. As mentioned above, the ferrite bead 1 is comprised of metal
powder which is pressed into a mold and sintered into shape. Alternative manufacturing
such as extrusion could also be used. The shape of the ferrite bead 1 can be varied
to accommodate various sizes of coils or various shapes of housings into which the
EMI protective system of the present invention may be incorporated, e. g. in electrical
The ferrite bead of Fig. 12 is of a regular cylindrical
tubular shape having constant inner and outer diameters throughout the axial length
of the ferrite bead. The ferrite bead shown in Fig. 13 has the general shape of
a dumbbell. In other words, at both axial ends of the ferrite bead, there is a cylindrical
portion having a larger outer diameter that the central cylindrical portion. The
inner diameter of the ferrite bead is preferably constant throughout the axial length
of the ferrite bead. The ferrite bead of Fig. 14 has generally two portions of different
outer diameter with the inner diameter of the ferrite bead being preferably constant
throughout the axial length of the ferrite bead. The coil may be wound on the ferrite
bead over the entire axial length of the ferrite bead (in particular in case of
the ferrite bead shown in Fig. 12), or it may be wound only on those portions of
the ferrite bead having the smaller outer diameter (in particular in case of the
ferrite beads shown in Figs. 13 and 14).
It should be understood that the foregoing description
is only illustrative of the invention. Various alternatives and modifications can
be devised by those skilled in the art without departing from the invention. For
example, the location of the female contacts and the contact pins could be reversed
such that the contact pins are comprised in the connector whereas the female contacts
are disposed in an associated socket. In general terms, the EMI protective system
of the present invention may be applicable to any feedthrough leads or conductors.
Further, for example, based on specific filtering requirements, different combination
of filtering units can be used as follows: one coil and ferrite bead EMI protective
device per circuit; two coil and ferrite bead EMI protective devices per circuit;
one coil and ferrite bead EMI protective device and one ferrite bead EMI protective
device per circuit; each with different combinations of ferrite materials and geometries.
Accordingly, the present invention is intended to embrace all such alternatives,
modifications and variances which fall within the scope of the appended claims.