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Dec. 24, 1946.
_H. D. HOEKSTRA
2,413,045 ‘
ENGINE STARTING MECHANISM
Filed Feb. i9, 1941
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H. D. HOEKSTRA
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2,413,045
ENGINE STARTING MECHANISM
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Filed Feb. 19, 1941
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Dec.v24, 1946.
2,413,045
H. D. HOEKSTRA
ÉNGINE STARTING MECHAN I SM
Filed Feb. 19, 1941
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2,413,045
Patented Dec. 24, 1946
UNITED STATESÃ PATENT V OFFICE
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ENGINE STARTING MECHANISM
Harold D. Hoekstra, Rockville, Md.
Application February 19, 1941, Serial No. 379,705
1 claim. (o1. 18s-_39)
1
er of the spring motor type adapted for use in
cranking internal combustion engines of the air
plane type.
_
“An object of my invention is to provide a start
er of this type which will be light weight, simple,
2
Fig. 7 is a fragmentary sectional view of the
starter, showing to advantage the clutch with
the rollers omitted;
Fig. 8 is a sectional view taken on the line 8-8
of Fig. ’7, looking in the direction of the arrows,
showing the clutch with rollers mounted in clutch
My invention relates in general to engine
starting mechanisms and in particular-to a start
_ cage.
»
Fig. 9 is a fragmentary elevational view of the
and inexpensive, being particularly adapted for
starting motor drive shaft;
use with low and medium powered aircraft. ’
Fig. 10 isla fragmentary sectional view of a
modiñed form of clutch, for use in the present
Another object is to provide a starter of this
type in which a varying amount of energy may
invention, the rollers being omitted.
be stored (at a rapid or slow rate) ' and which
Fig. 11 is a sectional View taken onV the line
energy may be expended as' desired by the oper
ll--H of Fig. 10, looking in the direction of the
arrows, showing thismodiiied form of clutch in
_end elevation,
Fig. 12 is a fragmentary detail sectional view
>taken. on the >une |2-a 2 of Fig. 11, poking in
' ator.
It is also the object of this invention to
provide a starter which canot be wound to an- ex
cessive degree either by the operator, or by an
engine back-nre.
-the direction of the arrows, showing to advantage
Still another object of my invention is to pro
vide a novel release and clutching means -which
_ the modified form of roller, the latter being shown
in side elevation, and _
will insure ready release and positive clutching
Fig. 13 is an elevational view of a tooth frag
action and which will be free-running with no
ment of the worm showing a conventional form 0I"
rubbing action when disengaged.
thread superimposed Íthereon, in dotted lines,
A further object of this invention is 'to provide
25 pressure and pitch lines being also illustrated
means whereby the eiiicient and desireable com- i .i
_ thereon.
pression type spring with its rectilinear motion
In order to villustrate the application of my
may be utilized to secure rotary motion.
invention I have shown in Fig. 1 a fragment of
Another object of this invention is to provide
safety means to harmlessly dissipate the stored
an airplane engine I5 and its crankshaft IS,
a pilot’s seat I1, and an engine starting mecha
energy in the starter in the event of clutch failure _ 30 `nism, generally designated I8. The engine start
or inadvertent release.
Other objects of the invention will be mani
fest from the following description of the pre
ferred form of the invention, taken in connec
tion with the accompanying drawings, wherein
Fig. 1 is a side elevational view of an airplane
engine starter constructed in accordance with the
present invention, illustrating its application to
an engine, the latter being fragmentarily shown;
Fig. 2 is a longitudinal sectional View of the
starter motor, portions thereof being broken away
to disclose details;
Fig. 3 is an end elevational View of the starter
ing mechanism is operatively connected to the
crankshaft i6, said starting mechanism being
fastened or secured tothe engine block by bolts
35
I9.
Y
My engine starting mechanism comprises a
cylindrical shell 2B one end of which is closed,
the opposite end being equipped with a housing
2 I, which latter, in'conjunction with the shell 20,
provides a casing for details of the starter mecha
nism hereinafter described.A These details in
clude a shaft 22 which extends axially through
said shell and housing and has formed on the
engine end an inner race 23 of a roller clutch.
vOn
the shaft 22 a coarse pitch multiple thread
.45
being fragmentarily shown;
24 is provided and mating therewith a large
Fig. 4 is a top plan View of a starter made in
diameter iianged nut 25. Formed on twosides
accordance with my invention, the starter motor
of
nut 25 are grooves 26 which mate with splines
being fragmentarily shown;
_
‘
,2l formed in the shell 20 to prevent rotation of
Fig. 5 is a fragmentary side elevational view of
my starter showing in detail portions v`of Athe 50 nut 25 while allowing _translational movement
motor, and associated appurtenances, the latter
“wind-up” mechanism;
_
_
Fig. 6 is a sectional view taken on line ß-S
of Fig. 5 looking in the direction of the arrows,
showing the motor casing engaging spring in
`,side elevation;
thereof along the longitudinal axis of the hous
ing. Compression springs 28 and 29, coaxial with
shaft 22, react against the housing 2| and nut
25 and serve to store energy when nut 25 is dis
placed towards the engine end of >starter mecha
2,413,045
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nism, Bearing 3B carries the thrust load from
shaft 22 into housing 2|. Fixedly attached to
Starting is accomplished by depressing the
starting pedal 51 in Fig. 1`Which operates cable
shaft 22 is worm wheel 3| which reacts with a
worm 32 attached to shaft 33 as shown to advan
58 and pulls down lever 59. Lever 59 is rotatably
attached to bolt 43' by means of boss 44. Formed
vin lever 59, is slot 60 which mates with pin 6|
anchored in housing 35. Spring 62 tends to ro
tate the lever 59 in a direction opposite to that
tage in Fig. 3. Shaft 33 is carried by a bearing
34 formed in a drum housing 35. Worm 32 and
shaft 33 are rotatable, in one direction only, by
the drum 3S of a drum housing 35 through a con
produced by tension in cable 58 and acts to pre
ventionalratchet and pawl mechanism 31 and
vent unintentional release of the starting mecha
38 respectively. The pawls are engaged, for 1a 10 nism. Clutch engaging spring 63 is attached to
manifest purpose, by springs 39 as shown to ad
lever 59 and through a portion of the travel of
vantage in Fig. 5. Worm 32 and shaft 33 are ro- .
lever 59 bears upon button 53 depressing the
tated in a direction to cause rotation of worm
same. As the button 53 is depressed, it operates
wheel 3| in the “wind” direction as shown by the
to advance the clutch rod 52 and places the clutch
arrow in Fig. 3 by means of cable 40 passing
in an operative position and at the same time
around drum 36. Cable 40 is trained around pul
lever 59, by means of pin 6|' and slot 60, disen
ley 4| and passes into the cabin or’cockpit ofthe
`gages the worm 32 from the worm wheel 3|
airplane and is there attached to handle 42. The
thereby allowing the springs to utilize the stored
handle 42 is positioned adjacent the seat -|1 for
energy and rotate the engine to be started.
convenient; accessibility to the pilot for winding 20
In the event that the starter springs have been
partially or fully compressed and the lever 59 is
the motor of the starter mechanism, as shown in
Fig. 1. The return rotation of drum 36 is ac
operated while the engine is running or if there
complished by means of a torsion' spring 43, the
is clutch slippage, the stored energy in springs 28
two ends of which are anchored in housing 35
and 29 cannot be utilized in the usual manner
and drum 36 respectively. The worm and hous
and must be dissipated in some other manner to
ing assembly is rotatably mounted on bolt 43'
avoid damage to the starter. This is accom
which is anchored in boss 44 formed on shell 29,
plished by means of a seal 64 attached to the
to permit disengaging worm 32 from worm wheel
flange of nut 25 thus forming an air buffer cyl
3|.
inder in shell 29, as shown to advantage in Fig. 2.
A basically ~conventional roller type over 30 A metering valve 65 is provided in shell 20, con
running clutch, such as shown in Figs. 2, '1, and 8,
sisting of an orifice setscrew 66 to permit adjust
is mounted in the engine end of the starter
ment of the airflow therethrough and conse
mechanism. The clutch comprises an outer race
quently to allow adjustment to the proper de
45 which is attached to engine I5, inner race 23,
gree of buil‘lng to prevent injury to the starting
and rollers 45. A novel arrangement is provided
mechanism.
`
to prevent the rollers contacting the outer race
Preferably, as shown in Fig. 13, the threads of
45 during the over-running or disengaged period.
the worm 32 and Worm wheel 3| have the meshing
This consists of roller cage 41 with spring mem
faces thereof rounded so that the pitch line is
bers 48, pin 49, slots 50 vand 5| of the inner race
substantially as indicated at X while the pressure
23 and cage 41 respectively, clutch rod 52, but 40 angle lines are as indicated at Y. This embodi
ton 53, and spring 54. The rollers are kept free
ment'of the invention taken with the preferred
of the outer race 45, except when starting. The
location of bolt 43’ in close proximity to the
axial movement of clutch rod 52 is transformed
extension of the pressure angle line Y, whilst
into rotary motion by means of pin 49 and slot
being a substantial distance from pressure angle
59 in the inner race 23. Then by means of pin
.line Z, permits reversibility in the “wind” direc
49 and slot 5| in cage 41, the roller cage is ro
tion, to prevent damage from reverse engine rota
tated thus bringing the rollers out of engagement
tion due, for-example, to back-nre during contact
with outer race 45.
of worm Wheel 3| and Worm 32 because of sud
den release of pedal 51 immediately after start
Another type of over-running clutch which has
been found to work very satisfactorily is shown 50 ing. It will be readily seen that the tendency of
in Figs. 10, l1 and 12 wherein conical rollers 46’
worm wheel 3| to rotate in the “start” direction
are employed and react between the inner race
shown on Figure 3 Will, due to the shape of the
23’ and the conical outer race 45’. This type of
meshing teeth on both worm wheel 3| and worm
over-running clutch permits direct axial move
32,'eXert a force substantially along the line Y
ment of clutch rod 52 to engage or disengage.
C71 Cil of Figure 13. Since by specification bolt 43’ is in
The operation of the starting mechanism is as
close proximity to line Y extended, there is no
follows: To’store energy or to wind-up the starter
appreciable tendency for the worm and drum
motor, the pilot or operator pulls handle 42 and
assembly and the housing 35 in which they are
cable 49 rotates drum 36 and the worm 32 -Which
mounted to pivot about bolt 43’. Hence the teeth
in turn rotates worm Wheel 3| in the direction of 60 will remain in mesh and the system may be con
the “wind-up” arrow shown in Fig. 3.. Rotation
sidered irreversible. However, rotation of Worm
of the worm wheel 3| turns the threaded shaft 22
wheel 3| in the “wind” direction applies force to
and nut 25 is moved in a direction to compress
the worm 32 along a line normal to the mating
springs Y28 »and 29. Storage of energy in the
teeth faces subjected to the force and hence dis
springs can be stopped at any point desired and
placing the Worm 32 out of contact with worm
it "is impossible-to compress springs 28 and 29 to
wheel >3| by pivoting of housing 35 and its as
an excessive degree through manual energy
sembled components about bolt 43’. Hence, in
storage or through back-fire since the nut 25
this direction the system is reversible. As is well
travels oif the- threads of shaft 22 when a pre
known to those versed in the art, spring 54,
determined compression value is reached, 'as'
though it will tend to disengage the Vclutch upon
shown at 55 in Fig. 2. The ends of the threads on
release of pedal 51, will not normally have suin
cient force to overcome clutch friction and hence
shaft 22 and in nut 25 may beA rounded, as at 55
in-Fig. 2, to avoid a “dead center” position, when
the above described worm reversibility is neces
vthe starter is fully wound, thus'insuring positive,
quick release for starting.
sary.
It is to be understood that various changes may
2,413,045
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be made in the details of construction, proportion
and arrangement of parts Within the scope of the
claim hereto appended.
What is claimed is:
said Worm wheel and located in close proximity
to the projection of a line passing through the
pitch circle of the said worm Wheel normal to the
teeth faces having the lesser pressure angle and
A spring motor, means to store energy in the mo
tor including a worm and Worm wheel, the teeth
of the said Worm and Worm Wheel having faces on
at the point of Worm and Worm Wheel contact
so as to permit relative translation between said
Worm and worm Wheel substantially parallel to
one pair of mating tooth faces and at an appre
one side inclined at a greater pressure angle than
ciable angle to the adjacent pair of mating tooth
the faces on the opposite side of the said teeth, the
said Worm being pivotally mounted with the 10 faces.
pivot axis substantially parallel to the axis of the
HAROLD D. HOEKSTRA.
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