Mounting structure for an electronic parts unit of an outboard engine

An outboard motor including an improved mounting arrangement for electronic components wherein they are mounted so that induction air will pass across and cool them. In addition, the electronic components are mounted on a circuit board and the mounting of the circuit board relative to the engine is in such a direction that the vibrations generated by the outboard motor are less likely to damage the electronic module.

BACKGROUND OF THE INVENTION 
This invention relates to a mounting structure for an electronic parts unit 
of an outboard motor and more particularly to an improved mounting 
structure for an electronic parts unit that precludes the likelihood of 
damage. 
In outboard motors, there is an increasing use of electronic units for 
controlling the operation of various components of an outboard motor. Such 
components may include microcomputers or the like which are mounted on a 
substrate such as a printed circuit board and which are potted in a 
suitable potting compound such as a resin. Although the potting compound 
is employed for protecting the circuit board and components from damage, 
the nature of the potting is such that air gaps may be formed around the 
various components. Due to the compact nature of an outboard motor, the 
electronic unit is mounted normally in such a manner that it experiences 
the vibrations of the outboard motor during its operation. The presence of 
air gaps in the potting compound and these vibrations can frequently cause 
damage to the printed circuit board or substrate or the connection between 
circuit and the discrete components. 
It is, therefore, a principal object of this invention to provide an 
improved mounting arrangement for the electronic unit of an outboard 
motor. 
It is a further object of this invention to provide a mounting arrangement 
for the electronic unit of an outboard motor that minimizes the likelihood 
of damage. 
In addition to the danger of damage to the electronic components from 
vibration, the compact nature of the outboard motor and the mounting of 
the electronic unit in proximity to the internal combustion engine gives 
rise to a further difficulty. The outboard motor and particularly its 
internal combustion engine is normally mounted within a protective cowling 
so as to protect the components from water, and particularly salt water 
when the motor is operated in a marine environment. However, the 
protective cowling tends to confine the heat generated by the internal 
combustion engine and this heat can very well damage the electronic 
components, many of which are extremely heat sensitive. 
It is, therefore, a still further object of this invention to provide an 
improved mounting arrangement for the electronic unit of an outboard motor 
that affords cooling of the electronic unit. 
SUMMARY OF THE INVENTION 
A first feature of this invention is adapted to be embodied in a mounting 
arrangement for electronic components of an outboard motor or the like. 
The electronic component consists of an electronic module having a 
substrate carrying a circuit and at least one electronic component mounted 
on the substrate. The electronic module is stronger in one direction than 
in another direction. The outboard motor vibrates during its operation and 
the vibrations are strongest in a first direction. In accordance with this 
feature of the invention, the electronic module is mounted so that the one 
direction is aligned with the first direction of vibration of the outboard 
motor. 
Another feature of the invention is also adapted to be embodied in a 
mounting arrangement for the electronic components of an outboard motor or 
the like. In accordance with this feature of the invention, an internal 
combustion engine is provided that is contained within a protective 
cowling. An electronic component is mounted within the cowling and the 
cowling has an air inlet communicating with the atmosphere and the 
interior of the cowling for delivery of induction air to the internal 
combustion engine. In accordance with this feature of the invention, the 
electronic component is positioned so as to be interposed in the path of 
air flow from the air inlet to the engine induction system for cooling the 
electronic component.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring first to FIG. 1, an outboard motor constructed in accordance with 
an embodiment of the invention is identified generally by the reference 
numeral 11. The outboard motor 11 includes a power head, indicated 
generally by the reference numeral 12, and which includes an internal 
combustion engine 13 that is enclosed within a protective cowling 14. In 
the illustrated embodiment, the engine 13 is of the V type although it is 
to be understood that the invention may be utilized in conjunction with 
engines of other types and other engines than reciprocating engines. 
The engine 13 has its crankshaft vertically disposed and drives a drive 
shaft (not shown) that extends through a drive shaft housing 15 into a 
lower unit 16. Contained within the lower unit 16 is a suitable forward, 
neutral, reverse transmission through which the drive shaft drives a 
propeller 17. 
A steering shaft 18 is connected to the drive shaft housing 15 by means 
including upper and lower vibration absorbing assemblies 19 and 21. The 
steering shaft 18 is, in turn, journaled for rotation about a vertically 
extending axis by means of a swivel bracket 22. The swivel bracket 22 is, 
in turn, supported for pivotal movement about a horizontally extending 
pivot axis by means of a pivot pin 23. The pivot pin 23 is rotatably 
journaled in a clamping bracket 24 which is affixed in a suitable manner 
to a transom 25 of an associated watercraft. 
As has been previously noted, the outer cowling 14 is provided for 
encircling and protecting the internal combustion engine 13. However, it 
is necessary to provide a source of intake air for the induction system of 
the engine 13. For this purpose, the rear portion of the outer cowling 14 
is provided with a depressed portion 26 to which a cover plate 27 is 
affixed so as to form an air inlet cavity 28. A rearwardly opening air 
inlet 29 is formed between the cover plate 27 and the recessed portion 26 
so as to admit atmospheric air to the air inlet cavity 28. In turn, the 
wall 26 has an upstanding cylindrical portion 31 that defines an air inlet 
opening 32 that communicates the cavity 28 with an air space 33 that 
surrounds the engine 13. In this manner, inlet air may be drawn through 
the air inlet opening 29 and pass through the air inlet opening 32 to the 
cowling interior 33 for induction into the engine 13. This tortuous path 
insures against the introducton of water into the interior 33 of the 
cowling 14. 
Referring now additionally to FIG. 2, the engine 13, as has been noted, is 
of the V type and has cylinder banks 34 and 35 that define a generally 
planar area 36 in the valley of the V between the banks 34 and 35. The 
planar area 36 lies substantially immediately beneath the air inlet 
opening 32 of the outer housing wall 26 as may be clearly seen in FIG. 1. 
The engine and other components of the outboard motor create vibrations and 
the largest magnitude of these vibrations extend in a generally 
longitudinally extending plane as indicated by the line X--X in FIG. 2. 
The mountings 18 and 19 have resilience in this direction so as to afford 
some vibration damping between the hull 25 and the outboard motor 11. 
The outboard motor 11 is also provided with an electronic module, indicated 
generally by the reference numeral 37. The module 37 includes a number of 
electronic components 38, 39 and so on which are mounted on a substrate 
consisting of a printed circuit board 41 that contains a suitable 
electronic circuit or circuits. The components 38, 39 and so on may be of 
any known type such as microprocessors or other components for controlling 
the operation of the engine 13 or other accessories. The printed circuit 
board 41 is supported within an outer housing or case 42 and the 
components 38 and 39 and board 41 are potted within a suitable potting 
composition 43 which may be formed from an epoxy resin or the like. 
The resin 43 is foamed in place and, therefore, it is possible for air gaps 
or bubbles to form when the resin sets. If these bubbles are formed around 
any of the components 38 or 39, as may be readily likely, vibrations of 
the unit 37 will put stresses on the substrate 41 which might cause it and 
its associated printed circuit to fracture and thus cause electrical 
malfunctions. In addition, the vibrations may tend to cause the connection 
between the components 38 and 39 and the substrate or board 41 to become 
broken or weakened which also can cause circuit problems or malfunctions. 
It should be noted that the board or substrate 41 and its connection to 
the components 38 and 39 is considerably stronger in a plane perpendicular 
to the substrate 41 than in the plane of the substrate 41. In accordance 
with the invention, therefore, the module 37 is mounted so that the 
substrate or board 41 is disposed at a right angle to the principal 
vibration axis X--X so that vibrations of the outboard motor 11 are less 
likely to damage the substrate 41, the components of the electronic module 
37 and the connections. 
The mounting arrangement for the unit 37 includes a mounting base 44 that 
is affixed in a suitable manner to the engine in the planar area 36. A 
generally cup shape mounting base 46 has a number of openings formed in 
its lower wall that receive elastomeric dampers 47 which, in turn, pass 
bolts 48 that are tapped into bosses 49 formed on the mounting plate 44 so 
as to resiliently support the mounting base 46 to the mounting plate 44. 
Mounting screws 50 affix a cover plate 51 to the module case 42 and, in 
turn, to bosses formed in the mounting base 46 so as to secure the module 
37 together and so as to insure water tightness. If desired, a suitable 
gasket (not shown) may be interposed between the cover 51 and the case 42. 
It should be noted that the mounting of the module 37 not only mounts it so 
that it is oriented with its strongest direction aligned with the 
direction of maximum vibration X--X but further in proximity to the air 
inlet opening 32 so that induction air drawn from the outside for the 
engine 13 will almost immediately and first pass over the module 37 so as 
to cool it and protect it from the heat generated by engine operation. 
FIG. 4 shows another embodiment of the invention wherein an electronic 
module, indicated generally by the reference numeral 71, is provided. This 
embodiment is substantially the same as the embodiment of FIG. 3. However, 
in connection with this embodiment, the containing box 72 of the circuit 
board or substrate 41 and the associated components 38, 39 and potting 
compound 43 are oriented so that mounting of the base 72 in the mounting 
bracket 46 will cause the base 72 to act, itself, as the cover plate. 
Thus, the cover plate of the previously described embodiment is 
unnecessary with this embodiment. 
Again, the unit 71 is mounted so that its strongest direction is aligned 
with the axis X--X of principal vibration of the outboard motor 11 so as 
to minimize the likelihood of vibration damage. Also, the unit 71 is also 
mounted immediately below the air inlet opening 32 so as to be cooled by 
the ambient air and protected from the heat generated by the operation of 
the engine. 
It should be readily apparent that the described embodiments provide a 
construction wherein the electronic module is protected since it is 
mounted so that its strongest point is aligned with the axis of maximum 
vibration and also so that it is aligned with the air inlet opening so as 
to be cooled by the induction system air drawn to the internal combustion 
engine immediately from the atmosphere. Although two embodiments of the 
invention have been illustrated and described, various changes and 
modifications may be made without departing from the spirit and scope of 
the invention, as defined by the appended claims.