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Патент USA US3087494

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April 30, 1963
'
J. D. FAIRCHILD
3,087,477
LASH ADJUSTING DEVICE
Filed Nov. 15, 1961
INVENTOR.
(JOHN D. FA/RCH/LD
BY
ATTORNEY
United States Patent Q? " ice
3,087,477‘
Patented Apr. 30, 1963
2
1
broken away of a rocker arm and a fulcrum embodying
3,087,477
LASH ADJUSTING DEVICE
John D. Fairchild, Ferndale, Mich, assignor to Earl A.
Thompson Manufacturing Company, a corporation of
Michigan
Filed Nov. 13, 1961, Ser. No. 151,227
2 Claims. (Cl. 123-90)
the lash adjuster of this invention;
FIGURE 2 is a top view of such a rocker arm and
fulcrum;
FIGURE 3 is an elevational view of the one-way drive
adjusting member of such a lash adjuster; and
FIGURE 4 is an exploded perspective view of the pair
of adjusting members of such a lash adjuster.
Referring in more particularity to the drawings, a rocker
This invention relates to mechanical lash adjusting
systems for engine valve actuating trains, and more par 10 arm 10 which may be of the trough-shaped or dished
yariety is fulcrumed intermediate its end about a down
ticularly to a type of spring-loaded lash adjuster wherein
wardiyfacing semi-spherical fulcrum 12 positioned on
potential lash is deliberately introduced into the valve
an upright stud 14 ?xed in the engine 16. Means forming
train by fully compulsive means which is extremely simple
a push rod abutment 18 at one end of the rocker arm co
and rugged and which is not adversely a?ected by inertia
operate with a push rod 20‘ operated by the conventional
conditions during engine operation.
15
rotary cam, not shown. Means forming a valve stem
Recent developments in the mechanical lash adjuster
abutment 22 at the other end of the rocker arm cooperate
?eld for modern automotive engines have taught the
with the stem of a conventional valve 24-‘ which is biased
desirability of providing a force-multiplying mechanism
upwardly against its seat, not shown, by means of a valve
of the annular or rotary wedge variety having an in
herently self-locking angle considerably below the critical
seating spring 26.
This mechanism is shifted in a direction
The lash adjusting device of this invention serves to
to introduce potential lash while the valve is unse-ated to
vary the elfective length of the valve actuating train by
controlling the upward and downward adjustment of the
friction angle.
insure positive, ?rm seating of the valve; it is then biased
rocker arm fulcrum 12 in relation to its supporting stud
in the opposite direction to wipe out such potential lash
while the valve is seated to insure quiet operation and 25 14. To this end, the stud 14 may include axially extend
ing splines 28 around its mid-portion and threads 30 on
full lift on the following unseating stroke. Furthermore,
its upper end. The fulcrum member ‘12 may include a
because of the diverse operating conditions of modern
central aperture embodying splines 32 which mate with
automotive engines which render the niceties of critical
the splines 28v on the stud to position the fulcrum for
friction requirements wholly unreliable, the means for
shifting the wedge device in the direction of increased 30 axial motion and against rotary motion thereon. The
upper surface of the fulcrum 12 may include a rotary
inclined ramp surface 34 embodying a self-locking helix
angle extending through a full circle. A hole 36 in the
nection as well as a positive driving connection. For
upper poriton of the member 12 is adapted to receive one
truly successful use in mass production high speed engines,
moreover, such positive driving means must be extremely 35 end of a lash take-up spring, explained below.
To control the axial position of the fulcrum member
simple for both economic and maintenance reasons as
12 on the stud 14, another adjusting member 38 com
well as being free from adverse in?uence by inertia forces
prising a one-Way driving arrangement may be rotationally
which change with engine speeds .
positioned on the stud 14. The member 38‘ is held
Accordingly, it is an object of the present invention to
against upward axial motion by means of a washer 40
provide a lash adjusting device including a purely one-way
and a pair of lock nuts 42 positioned on the threads 30
abutment drive arrangeemnt for a self-locking rotary
of the stud. Adjustment of the nuts 42 serves to effect
wedge which is positive in action because of compulsive
semi-permanent adjustment in the effective length of the
driving and reaction connections and absence of critical
valve actuating train. The member 38 is thus positioned
frictional balances, is extremely simple of structure involv
lash while the train is loaded must constitute a positive
one-way drive including a fully compulsive reaction con
ing relatively few moving parts, and is designed to min
imize adverse in?uences produced by changing inertia
by means of an aperture 44 for rotary motion on the stud
forces.
A more particular object of the present invention is to
provide a pair of co-axially positioned and relatively
rotatable adjusting members having mating rotary in
portion 46 which terminates at its lower end in a rotary
inclined ramp surface 47 mating with the surface 34 of
the fulcrum member. A hole 48' in the upper body por
tion of the adjusting member may be provided to receive
clined ramp surfaces on their mutually contacting ends
embodying a self-locking helix angle extending through a
full circle, which members are compulsively rotated rela
the other end of a lash take-up spring, explained below.
An actuating arm 50 integral with the adjusting member
38 may extend radially and normal to the axis fro-m the
tive to one another on the valve opening stroke to intro
14, and includes a downwardly depending annular body
upper portion of the adjusting member 38, and through
duce potential lash into the valve train and biased in the 55 a distance which carries its end beyond the lateral con
?nes of the upwardly extending side wall of the rocker
opposite direction after the valve seats to preclude actual
arm 10.
lash from the train.
A cut-out portion 52 of one side wall of the rocker arm
Further objects and advantages of the present invention
forms an actuating shoulder 54 in abutting engagement
will be apparent from the following detailed description, 60 with the side of the arm 50. Clockwise oscillatory motion
with reference to the accompanying drawings in which
of the rocker arm about its fulcrum 12 (FIGURE 1)
like reference characters refer to the same parts through
brings the shoulder 54 into abutting relationship with the
out the several views, and in which:
arm 50 which drives the adjusting member 38 in a clock
FIGURE 1 is a sectional elevational view with parts
wise direction (FIGURE 2) about the stud 14. The cut
3,087,477
3
out portion 52 of the rocker arm wall is of sufficient extent
so. that it will not interfere with the new, shifted position
the placement of the parts—particularly of the force
multiplying mechanism including its operating abutment
of the operating arm 50 as the rocker arm returns in a
minimizes adverse in?uences caused by momentum and
counterclockwise direction about its fulcrum (FIGURE
inertia forces during high speed engine operation.
1) on the valve seating stroke.
While the above described embodiment constitutes a
A coiled torsion or lash take-up spring 56, having its
upper end anchored in the hole 48 in the adjusting mem-‘
ber 38 and its lower end anchored in the hole 36 of the
fulcrum member 12, is provided to bias the upper of the
preferred mode of carrying out this invention, many other
forms might be adopted within the scope of the actual in?
vention, which is variously claimed as:
1. A lash adjusting system of the mechanical type for‘~
two adjusting members in a direction which translates the 10 a valve operating train of an engine comprising in comlower one ‘downwardly on the stud in the direction of de
'bin-ation therewith
creased lash. This spring is too weak to turn the mem
ber 38 in relation to the rotationally ?xed member 12
when the valve train is loaded by the force of the valve
a pair of co-axially positioned and relatively rotatable"
adjusting members having mating rotary inclined"
the valve is seated to drive the member 38 counterclock
ramp surfaces on their mutually contacting ends em~
bodying a helix angle and extending through no more:
than a full circle,
wise (FIGURE 2) to decrease the effective length of the
one of the adjusting members being secured against'
valve actuating train.
In operation, with the parts positioned as shown in the
rotation relative to the other in a direction which’
seating spring 26; however, the spring is operative when
drawings, the lash adjusting mechanism will operate once
on each open-ing and closing cycle of the valve in re
sponse to the driving cam. As the cam forces the push
rod 20 upwardly to pivot the rocker arm in a clockwise
direction about its fulcrum on the valve opening stroke,
the abutment shoulder 54 will contact the abutment arm
50 and rotate the adjusting member 38 in a direction
which allows upward translation of the fulcrum 12 to in
troduce an increment of potential lash into the train. As
the rocker arm pivots in the opposite direction on the
valve closing stroke, the abutment members move away 30
from each other because the self-locking angle of the
mating helix surfaces 34, 47 hold the member 38 in its
shifted position. This self-locking feature of the helix
angle retains the recently introduced increment of po
tential lash in the actuating train until the valve is fully
and positively at rest on its seat, as can be understood.
After the valve seats, the cam still has several more de
grees of falling contour because of the shortened effect
of the train. Thus, as soon as the valve seats, the lash
take-up spring 56 becomes operative to drive the adjust 40
would vary the effective length ‘of the train and the
other adjusting member being rotatable in one direction and return through a limited stroke to de
crease and increase, respectively, the effective length
of the train by a predetermined amount,
a single pair of one-way drive abutments movable to
ward and away from one another between spaced
and engaged relationships in response to valve open
ing and valve closing motion of the train, respec
tively, one of the abutments being associated with
the other adjusting member and the other abutment
being located to engage the one abutment part way
through the valve opening motion of the train and
thereafter compulsively rotate the other adjusting
member in the one direction from a mid-stroke po
sition through the distance required to reach the
limit of its stroke to create a corresponding amount
of potential lash in the train,
.
the helix angle of the ramp being inherently self-locking
against the force of valve train load to retain such
amount of potential lash in the train during valve
closing motion of the train as the abutments disen
gage and move away from one another,
ing member 38 in a counterclockwise direction (FIGURE
and a lash take-up spring having insufficient force to
2) to :translate the fulcrum member 12 downwardly as
rotate the other adjusting member while the train is
fast as the receding cam contour permits to wipe out any
loaded and connected to rotate the other adjusting
actual lash in the train. In normal operation, this will
45
member in the return direction away from its stroke‘
swing the arm abutment 50 only part of the way back
limit to a mid-stroke position through the distance:
towards the shoulder abutment 54. On the next valve
required to remove actual lash from the train as the;
opening stroke, the shoulder 54 will pick up the arm 50 at
load on the train is relieved by seating of the valve.
this mid-point and again move it to the extreme position
2. A lash adjusting system of the mechanical type for‘
to introduce lash to insure proper valve seating.
Thus, a lash ‘adjusting device has been disclosed which 5 O a valve operating train of ‘an engine comprising in comserves, by means of a single pair of positive acting abut
“bination therewith
ments ‘forming a fully compulsive driving connection and
the splined stud forming a fully compulsive reaction con
nection, to shift an inherently self-locking rotary wedge
through a variable distance to introduce a corresponding
amount of potential lash into the train.
This is done
during the last portion 'of each valve opening stroke,
such lash being retained on the valve closing stroke by
the self-locking character of the wedge or force-multi
plying mechanism until the valve seats, at which point the 60
lash take-up spring operates to increase the effective length
of the train as fast as the receding cam contour permits.
a fulcrum,
a trough-shaped rocker arm mounted for oscillatory‘
motion about the fulcrum to transfer motion between.
a push rod and a valve stem,
an adjustable mounting for the fulcrum including an;
upright stud,
a pair of co-axially positioned and relatively rotatablev
adjusting members on the stud and having mating
rotary inclined ramp surfaces on their mutually con-
tacting ends embodying a helix angle extending:
through no more than a full circle,
The. amount of potential lash removed by this spring dur
ing normal “warmed-up” operation will shift the force
mult-iplying mechanism through only par-t of the avail 65
able lash eliminating distance, thus only a corresponding
one of the adjusting members being associated with the
increment of potential lash will be introduced by the one
way drive abutments on the next opening stroke. Thus,
the increment or amount of potential lash will vary with
the lengths of the parts relative to each other and to the 70
member being rotatable in one direction and return
through a limited stroke to decrease and increase,
engine.
Enough extra travel of the force-multiplying
mechanism may be provided to compensate for wear of
the parts.
Furthermore, the extreme simplicity of the device
renders it available for mass production purposes, and 75
fulcrum and being secured against rotation relative
to the other in a direction which would vary the
effective length of the train and the other adjusting
respectively, the effective length of the train by a pre
determined amount,
a single pair of one-way drive ‘abutments movable to
ward and away from one another between spaced
and engaged relationships in response to valve open
ing and valve closing motion of the train, respectively,
one of the abutments being associated with the other
3,087,477
6
adjusting member and the other abutment being locat-
loaded and connected to rotate the other adjusting
ed ‘on the rocker ‘arm to engage the One abutment
member in the return direction away from its stroke
Part Way through the Valve Waning ‘motion of the
limit to a midast-roke position through the distance
train and thereafter compulsively rotate the other adjusting member in the one direction fir-om a mid- 5
[required to remove actual lash from the train as the
load on the train is relieved by seating of the valve.
stroke position through the distance required to reach
the limit of its stroke to create a corresponding
amount of potential lash in the train,
the helix :angle of the ramp being inherently self-locking
References Cited in the ?le of this patent
UNITED STATES PATENTS
against the :force of valve train load to retain such 10
amount of potential lash in the train during valve
2132251 4
2642048
closing motion of the train as the abutments disen-
2’743’713
Russell
‘gage and move away ?rom one another,
2’934’051
Drew
3’009’450
Engem'ggn' """""""" ‘TN; '21’ 1961
and a lash take-up spring having insu?icient force to
rotate the other adjusting member while the train is 15
Goodwin ____________ __ June 22’ 1943
Russell ______________ __ June 16 1953
May 1’ 1956
"""""""" “ A. r 26’ 1960
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