Field
[0001] The present application relates to an electronic control unit (ECU).
Background of The Invention
[0002] Electronic control units (ECUs) for vehicle engines typically comprise a microprocessor,
possibly along with other co-processors, and other electrical and electronic components
mounted on a printed circuit board (PCB) with one or more signal conductors extending
from the PCB in order to connect the microprocessor to a vehicle control network,
for example, a Controller Area Network (CAN) Bus, external sensors or telemetry equipment
or a vehicle antenna in order to control the vehicle.
[0003] As is well appreciated, vehicle engine compartments in particular can be difficult
operating environments and in order to shield the ECU, it is typical for an ECU to
be enclosed in a protective housing or shell.
[0004] Such housings can provide robust environmental protection, although any points from
which signal conductors pass through the housing can represent a point of failure,
making the PCB especially prone to electro-magnetic noise or interference (EMI) or
effect the electro-magnetic compatibility (EMC) of the ECU.
[0005] In the case of electrically conductive housings, metal spring connectors can be employed
to bridge between signal conductors and the housing to shield against EMI and maintain
EMC, however, such connections may not be sufficiently reliable or robust and can
be prone to failure.
[0006] Other solutions involve electrically conductive paste or tape but these can be labour
intensive to apply and can also suffer from reliability problems.
[0007] It is an object of the present invention to provide an improved electronic control
unit.
Summary
[0008] According to the present invention, there is provided an electronic control unit
(ECU) according to claim 1. Advantageous embodiments are provided in the dependent
claims.
[0009] Embodiments include a foam collar for each connector extending from an ECU PCB and
which in use provides contact between the electrical connector and the housing of
the ECU, thereby reducing EMC/EMI, issues.
[0010] Foam collars employed in embodiments of the present invention can be readily sized
and shaped to fit or be retro-fitted to any connector to seal any aperture of an ECU
housing.
[0011] Such collars can be compressed in a number of directions and so provide a high degree
of tolerance in fitting. Thus, use of such foam collars allows for a 360° contact
on cylindrical and non-cylindrical openings.
Brief Description of The Drawings
[0012] An embodiment of the present invention will now be described, by way of example,
with reference to the accompanying drawings in which:
Figure 1 is a perspective view of a co-axial electrical connector connected to a PCB
for an ECU according to an embodiment of the present invention;
Figure 2 is a perspective view of an electrically conductive foam collar for an ECU
according to an embodiment of the present invention;
Figure 3 is a perspective view of the electrical connector of Figure 1 with the electrically
conductive foam collar of Figure 2 located around a ground shield of the electrical
connector;
Figure 4 is a perspective view of the electrical connector and the electrically conductive
foam collar of Figure 3 with the electrically conductive foam collar clamped between
a shell portion of a housing and the ground shield of the electrical connector; and
Figure 5 is a perspective view of the electrical connector and the electrically conductive
foam collar of Figure 3 within a two-part shell, each part being fixed together to
clamp the electrically conductive foam collar against the ground shield of the electrical
connector.
Detailed Description of The Embodiment
[0013] Referring now to Figure 1, there is shown a portion of a printed circuit board (PCB)
106 for an electronic control unit (ECU) according to an embodiment of the present
invention. An electrical connector 100 is mounted on the PCB 106. The electrical connector
100 may be one of a plurality of electrical connectors extending from the PCB 106,
however, only one is shown, but it will be appreciated that the principals described
for the connector of Figure 1 are equally applicable to other connectors extending
from the PCB.
[0014] In the illustrated example, the electrical connector 100 comprises a conventional
type radio frequency (RF) right-angled jack comprising a mount 101 including a plurality
of connections through to the PCB (only some of the ground plane connections 103 are
shown), with the signal conductor extending from a signal trace on the PCB, within
the mount and bending through 90 degrees within the mount to extend in a plane parallel
to the PCB and away from the edge of the PCB. The signal conductor 102 is surrounded
by a co-axial ground shield 104, with the co-axial ground shield 104 being electrically
coupled to the ground plane (not shown) of the PCB 106 through the mount 101.
[0015] In the illustrated example, a lug 108 is formed on an external surface of the ground
shield 104. The lug 108 can be of a type to facilitate a Bayonet Neill-Concelman (BNC)
or similar connection with a signal lead (not shown) extending from the ECU, but it
can also be provided specifically to facilitate the present invention.
[0016] It will nonetheless be appreciated that the present invention is applicable to many
different forms of both RF connector and non-RF connectors including screw type Sub-Miniature
version A (SMA) connectors or push-on connectors.
[0017] It will also be seen that while in the illustrated example, the jack 100 is right-angled,
in variations of the example, the jack could extend vertically from the PCB 106.
[0018] Referring now to Figure 2, there is shown an electrically conductive foam collar
200 for the connector 100 of Figure 1. The electrically conductive foam collar 200
has a generally toroidal shape having an inner aperture 202 and an outer periphery
204. (It will be appreciated that the outer periphery as in this case need not be
strictly circular, but its shape will be defined by the aperture it is to be located
in as will be explained below.) In the illustrated embodiment the foam collar 200
has a slit 206 running from the inner aperture 202 to the outer periphery 204. The
electrically conductive foam collar 200 may be for example, formed of PORON® Condux
Plus™ by Rogers corporation. PORON® Condux Plus™ provides extremely low electrical
resistance of less than 1.29032 x 10
-6 Ohm/m
2 (0.002 Ohm/in
2) and so acts as an excellent conductor.
[0019] Referring now to Figure 3, the electrically conductive foam collar 200 can be fitted
around the co-axial ground shield 104 of a respective electrical connector 100. As
will be seen, the collar 200 can be located between the mount 101 and the lug 108
to maintain the position and orientation of the collar on the shield 104 prior to
further assembly. The collar 200 can be pushed over the end of the connector into
the required location or especially because of the presence of the slit 206, it can
be pushed onto the connector 100 from the side.
[0020] Referring now to Figure 4, the ECU in accordance with the preferred embodiment of
the present invention comprises a two-part shell. Typically, the PCB 100 is first
located in one portion 300 of the shell with any connectors such as the connector
100 extending past the wall of the shell. In the illustrated example, an edge 304
of the shell comprises a recess 302 providing a gap between the shield 104 and the
wall of the shell portion 300 which is filled by the foam collar 200.
[0021] Referring now to Figure 5, once the PCB has been located in the first portion 300
of the shell, a second portion 400 of the shell can be fitted to the first portion
300. The second portion comprises an edge 404 and when the shell portions 300, 400
are brought into contact, they mate along the edges 304, 404. In the illustrated example,
the edge 404 of the second portion of the shell also comprises a recess 402 which
lies in register with the recess 302 to form an aperture 500 through which the electrical
connector 100 passes and which is sealed by the foam collar 200.
[0022] As will be seen, the electrically conductive foam collar 200 is located and placed
between the connector 100 and the recesses 302, 402 of the shell so that, if the collar
is fitted to the connector during assembly of the ECU and before the connector 100
is located in the housing, when the housing is clamped over it, it will be in register
with the edge recesses 302, 402 thereby providing an electrical sealing of the shell
300, 400.
[0023] The fitting together of the mating edges 304, 404 of each shell 300, 400 of the two-part
shell clamps the electrically conductive foam collar 200 against the co-axial ground
shield 104 of the electrical connector 100. The shell portions 300, 400 can be clamped
together using, for example, screw type fittings or snap fit type fittings (not shown).
The shell portions 300, 400 are at least partially conductive and, in some cases,
comprise a metal casing.
[0024] The electrically conductive foam collar 200 is resiliently deformable so that when
clamped between the conductive portions of the shell 300, 400 and the co-axial ground
shield 104 of the respective electrical connector 100, the collar acts as an electrically
conductive gasket to close gaps between the ECU shell 300, 400, PCB 106 and electrical
connector 100 to provide an electrical sealing of the shell 300, 400. As will be appreciated,
this helps to reduce EMC/EMI, issues.
[0025] It will be appreciated, with the slit 206 provided, that in some cases the electrically
conductive foam collar 200 can be retrofitted to the ECU by pushing it into the aperture
500, thereby enabling the electrically conductive foam collar 200 to be fitted to
the ECU after the PCB 106 has been positioned within the shell. In particular, the
slit 206 in the electrically conductive foam collar 200 allows for its introduction
to the assembly of the ECU at any or multiple points in the production process.
[0026] The electrically conductive foam can be cut to size from sheets, allowing for uniform
contact between the connector 100 and the shell 300, 400 of the ECU.
[0027] In other embodiments not illustrated, the electrically conductive foam collar can
be clamped between the connector mount 101 and the inside surface of a wall conductive
portion of the shell rather than between two edges of the shell. Again, the electrically
conductive foam collar would be compressed between the inside wall of the conductive
portion of the shell and the connector mount 101 to provide an electrical sealing
of the shell.
1. An electronic control unit, ECU, comprising:
a body portion comprising a shell (300, 400) at least a portion of which is conductive;
a printed circuit board, PCB (106) positioned within the body portion;
at least one electrical connector connected to the PCB and extending from the PCB
through a respective aperture (500) in said shell, wherein the at least one electrical
connector comprises a signal conductor (102) surrounded by a co-axial ground shield
(104), the co-axial ground shield being electrically coupled to a ground plane of
the PCB; and
at least one electrically conductive foam collar (200), the or each collar located
around a co-axial ground shield of a respective electrical connector;
wherein the or each electrically conductive foam collar is resiliently deformable
so as to be clamped between the conductive portion of the shell and the co-axial ground
shield of the respective electrical connector to provide an electrical sealing of
the shell.
2. The electronic control unit of claim 1 wherein the or each electrically conductive
foam collar comprise a generally toroidal shape having an inner aperture (202) and
an outer periphery (204), the or each electrically conductive foam collar having a
slit (206) running from said inner aperture to said outer periphery enabling the or
each electrically conductive foam collar to be fitted to said ECU after said PCB has
been positioned within said body portion.
3. The electronic control unit of claim 1, wherein the shell is a two-part shell (300,400),
each part being fixed together to clamp the or each electrically conductive foam collar
against the respective co-axial ground shield of the respective electrical connector.
4. The electronic control unit of claim 3, wherein each part of said shell is fixed together
along mating edges (302,402), a mating edge of at least one part being recessed (304,
404) to define the or each aperture through which the or each electrical connector
passes.