U.S. patent application number 12/914366 was filed with the patent office on 2011-04-28 for lash adjuster.
Invention is credited to Robert T. MacVicar, Raji Rexavier.
Application Number | 20110094467 12/914366 |
Document ID | / |
Family ID | 43897310 |
Filed Date | 2011-04-28 |
United States Patent
Application |
20110094467 |
Kind Code |
A1 |
MacVicar; Robert T. ; et
al. |
April 28, 2011 |
LASH ADJUSTER
Abstract
In accordance with the present invention, a lash adjuster is
provided for minimizing stress on a valve train system in the event
of its failure. Specifically, the present invention lash adjuster
is for use in a valve train system having a cam for actuating the
opening and closing of a valve, where the cam has a select size and
shape for determining the velocity or acceleration of the valve's
opening and closing. The present invention lash adjuster generally
comprises a housing having a base and a plunger positioned within
the housing at a select axial clearance from the base. This
clearance is generally sized and shaped such that, in the event of
lash adjuster failure, a select maximum velocity or acceleration of
valve opening and closing is maintained, thereby minimizing stress
on the valve train system.
Inventors: |
MacVicar; Robert T.;
(Downers Grove, IL) ; Rexavier; Raji; (Clarendon
Hills, IL) |
Family ID: |
43897310 |
Appl. No.: |
12/914366 |
Filed: |
October 28, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61255601 |
Oct 28, 2009 |
|
|
|
Current U.S.
Class: |
123/90.53 |
Current CPC
Class: |
F01L 2820/01 20130101;
F01L 1/2411 20130101; F01L 1/26 20130101; F01L 1/181 20130101; F01L
2305/00 20200501 |
Class at
Publication: |
123/90.53 |
International
Class: |
F01L 1/22 20060101
F01L001/22 |
Claims
1. A lash adjuster for use in a valve train system, said valve
train system having a cam for actuating the opening and closing of
at least one valve, wherein said cam has a select size and shape
for determining the velocity of valve opening and closing, a member
having a lash adjuster to maintain zero clearance between at least
one valve tip and said member, said lash adjuster comprising, a
housing having a base, a plunger situated within said housing and
being situated at a select axial clearance from the base of said
housing, wherein the select axial clearance is sized and shaped
such that in the event of lash adjuster failure, a select maximum
velocity of valve opening and closing is maintained, thereby
minimizing stress on the valve train system in the event of lash
adjuster failure.
2. The lash adjuster of claim 1 wherein said member is a rocker
arm.
3. The lash adjuster of claim 1 wherein said member is a valve
bridge.
4. The lash adjuster of claim 1 wherein said member is a cam.
5. The lash adjuster of claim 1 further comprising a ball retainer
for retaining a ball near the base of said housing.
6. The lash adjuster of claim 5, wherein failure of said ball
retainer results in lash adjuster failure.
7. The lash adjuster of claim 5 further comprising a ball spring
for holding said ball against a seat in the base of said
housing.
8. The lash adjuster of claim 7, wherein failure of said spring
results in lash adjuster failure.
9. The lash adjuster of claim 7, wherein malfunction of the
engagement between said ball and seat results in lash adjuster
failure.
10. The lash adjuster of claim 1, wherein the select axial
clearance is sized to have a length of between about 0.01 inches
and about 0.03 inches.
11. The lash adjuster of claim 1, wherein the select axial
clearance is sized to have a length of about 0.02 inches.
12. The lash adjuster of claim 1, wherein the maximum velocity of
valve opening is between about 5 inches per second and about 14.40
inches per second and the maximum velocity of valve closing is
between about 15 inches per second and about 20 inches per
second.
13. The lash adjuster of claim 1, wherein the change in opening and
closing velocities of the valve remain relatively gradual.
14. A lash adjuster for use in a valve train system, said valve
train system having a cam for actuating opening and closing of at
least one valve, wherein said cam has a select size and shape for
determining the acceleration of valve opening and closing, a member
having a lash adjuster to maintain zero clearance between at least
one valve tip and member, said lash adjuster comprising, a housing
having a base, a plunger situated within said housing and being
situated at a select axial clearance from the base of said housing,
wherein the select axial clearance is sized and shaped such that in
the event of lash adjuster failure, a select maximum acceleration
of valve opening and closing is maintained, thereby minimizing
stress on the valve train system in the event of lash adjuster
failure.
15. The lash adjuster of claim 14 wherein said member is a rocker
arm.
16. The lash adjuster of claim 14 wherein said member is a valve
bridge.
17. The lash adjuster of claim 14 wherein said member is a cam.
18. The lash adjuster of claim 14 further comprising a ball
retainer for retaining a ball near the base of said housing.
19. The lash adjuster of claim 18, wherein failure of said ball
retainer results in lash adjuster failure.
20. The lash adjuster of claim 18 further comprising a ball spring
for holding said ball against a seat in the base of said
housing.
21. The lash adjuster of claim 20, wherein failure of said spring
results in lash adjuster failure.
22. The lash adjuster of claim 20, wherein malfunction of the
engagement between said ball and seat results in lash adjuster
failure.
23. The lash adjuster of claim 14, wherein the axial clearance is
sized to have a length of between about 0.01 inches and about 0.03
inches.
24. The lash adjuster of claim 14, wherein the axial clearance is
sized to have a length of about 0.025 inches.
25. The lash adjuster of claim 18, wherein the maximum acceleration
of valve opening is about 78,000 inches/second.sup.2 and the
maximum acceleration of valve closing is about 107,700
inches/second.sup.2.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Non-provisional patent application,
which claims benefit to U.S. Provisional Application Ser. No.
61/255,601, entitled "Lash Adjuster," filed Oct. 28, 2009, the
complete disclosure thereof being incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] The present invention generally relates to a lash adjuster
for use in a valve train system. Specifically, the present
invention is directed to a lash adjuster that provides a fail-safe
condition to avoid damage to a valve exhaust system upon failure of
a hydraulic lash adjuster.
[0003] As illustrated in FIG. 1a, it is known in the art relating
to internal combustion engines, such as diesel engines, and namely
locomotive diesel engines 101, to actuate two adjacent valves 120a,
120b of an engine cylinder 103 by a rotating cam. The cam generally
includes a select shape which determines the timing, lift,
velocity, and acceleration of the intake and exhaust valve
actuation. As shown in FIG. 1b, in order to open the exhaust valves
106a, 106b the cam shaft 108 rotates until a cam lobe 104 engages a
roller 110 located on a rocker arm 112. Once the cam lobe 104
engages the rocker arm 112, the rocker arm 112 engages a valve
bridge 114, which causes compression in adjacent springs 116a, 116b
causing the exhaust valves 106a, 106b to open.
[0004] Generally, valve systems are subject to various types of
deflection. For example, valve systems may be subject to thermal
expansion as the engine heats up and mechanical deflection due to
operational loads. If the valve sterns 120a, 120b thermally and
mechanically expand and elongate, the valves 106a, 1066 are unable
to fully close. Because the components of the valve system are
exposed to a range of temperatures throughout the cycle, a lash
adjuster is used to provide a means of self-adjusting the length of
the valve stems 120a, 120b to facilitate closure thereof. Lash
adjusters provide adjustability so that there is zero clearance at
all times between the valve bridge 114 and the valve sterns 120a,
120b, thereby allowing the exhaust valves 106a, b to operate
effectively, even when thermal expansion occurs. Valve systems may
incorporate two hydraulic lash adjusters 102a, 102b, received in
sockets 122a, 122b located at opposite distal ends of the cross-arm
portion of the valve bridge 114, to engage and directly act upon
the ends of the valve stems 120a, 120b.
[0005] FIG. 2 shows a prior art hydraulic lash adjuster 202 in a
closed position where a ball 230 is held against a ball seat 234 in
the lash adjuster 202 body by a light spring 238, thereby closing
the aperture 224 in the base 240 of the housing 236 of the lash
adjuster 202. However, when the exhaust valves begin to open, a
force is applied across the lash adjusters, causing a small amount
of oil to escape through the diametrical clearance of the lash
adjuster 202, situated between the plunger 242 and the sidewall of
the housing 236. This force also maintains the internal pressure
therein and, acting with the ball spring 238, situates the ball 230
against the seat 234 preventing oil from flowing out the aperture
224 defined in the base 240 of the housing 236. When the exhaust
valve is returned to its seat, the force across the lash adjuster
202 is relaxed and the pressure in the cavity 232 drops. This
allows the plunger 242 to move downward under the influence of the
plunger spring 244, causing the cavity 232 pressure to drop below
the oil supply pressure and allowing oil flow into the cavity 232
through the aperture 224, making up for leakage until the pressure
equalizes.
[0006] The cavity 232 of the lash adjuster 202 includes an internal
axial clearance 260 between the plunger 242 and the base 240 of the
housing 236. In the prior art lash adjuster 202 of FIG. 2, this
internal clearance 260 is about 0.1 inches. When the lash adjuster
202 is properly functioning, the force across the lash adjuster 202
acts so that the plunger 242 may only travel axially between about
0.001 inches and about 0.005 inches. However, when the lash
adjuster 202 fails, the lash adjuster 202 is no longer able to
effectively trap oil and maintain the force and pressure that
prevents the plunger 242 from traveling the full length of the
internal axial clearance 260. Therefore, when the prior art lash
adjuster 202 of FIG. 2 fails, the plunger 242 travels about 0.1
inches until it hits the base 240 of the housing 236.
[0007] Moreover, when the lash adjuster fails, because there is no
internal pressure within the lash adjuster due to the oil escaping
through supply channels--no force is exerted upon the valve to open
or close it until the plunger makes contact with the base of the
housing 236. Therefore, the valve does not begin to open or close
until the valve train lifts to about 0.1 inches. As shown in FIG.
3, when the valve train is lifted to about 0.1 inches, the cam has
already rotated to about 43 degrees (shown at 302). Similarly, when
the valve begins to close, the cam is rotated to an angle of about
150 degrees (shown at 320) and the valve train is lifted to about
0.1 inches.
[0008] The timing of valve actuation, in part, depends on what
point the cam (i.e. cam angle) is engaging the roller at a given
point in time. Because of the select shape of the cam, the
steepness of the cam corresponds to the velocity of valve opening
and closing. When a lash adjuster is working properly, the opening
and closing velocities of the valve gradually increase or decrease,
respectively, as the cam rotates. For instance, as illustrated in
FIG. 3, with respect to the properly functioning prior art lash
adjuster of FIG. 2, when the cam rotates from an angle of about 0
degrees to about 43 degrees (shown at 301), the opening velocity of
the valve gradually reaches about 60 inches/sec, at which point
(shown at 304) the valve is opened to about 0.1 inches. Similarly,
when the cam rotates to an angle of about 150 degrees (shown at
322), the valve begins to gradually close at a reducing velocity
from about -65 inches/sec until the cam is rotated to an angle of
about 158.5 degrees (shown at 328) and the valve reaches ramp
velocity. The valve continues to gradually close at a constant
velocity until the cam is rotated to an angle of about 180 degrees
(330), at which point the valve is closed.
[0009] However, when the prior art lash adjuster fails or
momentarily malfunctions, the opening and closing velocities of the
valve are no longer slow and gradual. In the prior art arrangement
of FIG. 2, when the lash adjuster fails or momentarily
malfunctions, the plunger travels about 0.1 inches before it
contacts the base of the housing 236. When this happens, the valve
gear is well beyond the end of the ramp and up the flank of cam
profile before the valve opens (the same is true on the closing
side of the event). As a result, the valve opens and closes at very
high velocities--as much as ten times ramp velocity.
[0010] For instance, as shown in FIG. 3, when the prior art lash
adjuster of FIG. 2 fails, instead of having a gradual opening
velocity, the velocity of the valve increases instantaneously from
about 0 inches/sec (shown at 308) to about 60 inches/sec (shown at
316). In this failed condition, as the cam rotates from about 0
degrees (shown at 300) to about 43 degrees (shown at 306), the
velocity of the valve remains at about 0 inches/sec (shown at 308).
However, when the cam reaches an angle of about 43 degrees, the
valve suddenly opens (shown at 316) at a velocity of about 60
inches/sec (shown at 304). Similarly, when the prior art lash
adjuster of FIG. 2 fails, the closing velocity of the valve is
abrupt, instead of gradual. As the cam rotates from about 140
degrees (shown at 319) to about 150 degrees (shown at 322), the
valve is slowly beginning to close at a gradually increasing
negative velocity. However, when the prior art lash adjuster has
failed, as the cam reaches an angle of about 150 degrees, the valve
makes contact with the cylinder head and the velocity suddenly
decreases (shown at 326) to a velocity of 0 inches/sec (shown 324).
When the valves open and close at high velocities, the valves, and
other system components, are subjected to high impact loads, which
frequently result in valve system failure. Thus, it is an object of
the present invention to provide a lash adjuster with a select
axial clearance, between the plunger and housing, that is generally
sized and shaped such that, in the event of lash adjuster failure,
a select maximum velocity of valve opening and closing is
maintained, thereby minimizing stress on the valve train system in
the event of such failure.
[0011] Additionally, when the prior art lash adjuster of FIG. 2
fails, the opening and closing accelerations of the valve become
abrupt instead of gradual. As shown in FIG. 4, when a prior art
lash adjuster is working properly, as the cam rotates from about 0
degrees to about 43 degrees, the opening acceleration of the valve
should correspondingly increase gradually from about 0
inches/secinches/sec.sup.2 to about 27,100 inches/sec.sup.2 (shown
between 400 and 402). However, when the lash adjuster fails, the
opening acceleration of the valve increases abruptly from 0
inches/sec.sup.2 (shown at 408) to about 329,900 inches/sec.sup.2
(shown at 404). In this failed condition, as the cam rotates from
about 0 degrees to about 43 degrees, the acceleration of the valve
remains at about 0 inches/sec.sup.2 (shown at 406). However, when
the cam reaches an angle of about 43 degrees (shown at 408), the
valve suddenly accelerates at a rate of about 329,887.1
inches/sec.sup.2 (shown at 404).
[0012] Similarly, when a prior art lash adjuster is working
properly, as the cam rotates from about 150 degrees to about 180
degrees, the closing acceleration of the valve should
correspondingly decrease gradually from about 30,000
inches/sec.sup.2 (shown at 412) to 0 inches/sec.sup.2 (shown at
411). However, when the lash adjuster fails, the closing
acceleration of the valve spikes to 380,900 inches/sec.sup.2 (shown
at 414) and decreases abruptly to 0 inches/sec.sup.2 (shown at
418). In this failed condition, as the cam rotates from about 150
degrees to about 180 degrees, the acceleration of the valve remains
at about 0 inches/sec.sup.2 (shown at 416). When the valves open
and close at high acceleration rates, the valves, and other system
components, are subjected to high impact loads, which frequently
results in valve system failure. Thus, it is a further object of
the present invention to provide a lash adjuster with a select
axial clearance, that is generally sized and shaped such that, in
the event of lash adjuster failure, a select maximum acceleration
of valve opening and closing is maintained, thereby minimizing
stress on the valve train system in the event of such failure.
SUMMARY OF INVENTION
[0013] In accordance with the present invention, a lash adjuster is
provided for minimizing stress on a valve train system in the event
of its failure. Specifically, the present invention lash adjuster
is for use in a valve train system having a cam for actuating the
opening and closing of a valve, where the cam has a select size and
shape for determining the velocity or acceleration of the valve's
opening and closing. The present invention lash adjuster generally
comprises a housing having a base and a plunger positioned within
the housing at a select axial clearance from the base. This axial
clearance is generally sized and shaped such that, in the event of
lash adjuster failure, a select maximum velocity and/or maximum
acceleration of valve opening and closing is maintained, thereby
minimizing stress on the valve train system.
[0014] The following description is presented to enable one of
ordinary skill in the art to make and use the invention and is
provided in the context of a patent application and its
requirements. Various modifications to the preferred embodiment and
the generic principles and features described herein will be
readily apparent to those skilled in the art. Thus, the present
invention is not intended to be limited to the embodiments shown,
but is to be accorded the widest scope consistent with the
principles and features described herein.
BRIEF DESCRIPTION OF DRAWINGS
[0015] FIG. 1a is a cross-sectional view of a prior art locomotive
diesel engine, of which the present invention fail-safe lash
adjuster is a part.
[0016] FIG. 1b is a cross-sectional view of a prior art valve train
system, of which the present invention fail-safe lash adjuster is a
part.
[0017] FIG. 2 is a cross-sectional view of a prior art lash
adjuster.
[0018] FIG. 3 is a chart depicting the relationship between cam
angle and valve opening and closing velocity of the present
invention fail-safe lash adjuster in comparison to prior art
lash-adjusters.
[0019] FIG. 4 is a chart depicting the relationship between cam
angle and valve acceleration of the present invention fail-safe
lash adjuster in comparison to prior art lash-adjusters.
[0020] FIG. 5 is a cross-sectional view of the present invention
fail-safe lash adjuster.
DETAILED DESCRIPTION OF DRAWINGS
[0021] In accordance with the present invention, a fail-safe lash
adjuster is provided for minimizing stress on a valve train system
in the event of its failure. The valve train system includes a cam
for actuating the opening and closing of at least one valve, where
the cam has a select size and shape for determining the velocity or
acceleration of valve opening and closing. The valve train also
includes a member having a lash adjuster to maintain zero clearance
between at least one valve tip and a member. This member may be in
the form of a rocker arm, a valve bridge, or a cam follower. The
lash adjuster comprises a housing and a plunger situated within the
housing and positioned at a select axial clearance from the base of
the housing. This axial clearance is sized and shaped such that in
the event of lash adjuster failure, a select maximum velocity
and/or acceleration of valve opening and closing is maintained,
thereby minimizing stress on the valve train system.
[0022] In one embodiment, shown in FIG. 5 in a closed position, the
present invention lash adjuster 502 includes a ball 530 that is
held against a ball seat 534 in the lash adjuster body by a light
spring 538, thereby closing the aperture 524 in the base 540 of the
housing 536 of the lash adjuster 502. In this embodiment, when a
valve of the valve train system begins to open, a force is applied
across the lash adjuster 502, causing a small amount of oil to
escape through the diametrical clearance of the lash adjuster 502,
situated between the plunger 542 and the sidewall of the housing
536. Additionally, the force applied across the lash adjuster 502
maintains the internal pressure therein and, acting with the ball
spring 538, situates the ball 530 against the seat 534 to prevent
oil from flowing out the aperture 524 defined in the base 540 of
the housing 536. When the exhaust valve is returned to its seat,
the force across the lash adjuster 502 is relaxed and the pressure
in the cavity 532 drops. This allows the plunger 542 to move
downward under the influence of the plunger spring 544, causing the
cavity 532 pressure to drop below the oil supply pressure and
allowing oil flow into the cavity 532 through the aperture 524
until the pressure equalizes.
[0023] Like the prior art lash adjuster of FIG. 2, when the present
invention lash adjuster 502 of FIG. 5 is properly functioning, the
force across the lash adjuster 502 acts so that the plunger 542 may
only travel axially between about 0.001 inches and about 0.005
inches. Moreover, like the prior art lash adjuster, when the
present invention lash adjuster 502 fails, it is no longer able to
effectively trap oil and maintain the force and pressure that keeps
the plunger 542 from traveling the full length of the internal
axial clearance 560. Moreover, when the lash adjuster fails,
because there is no internal pressure within the lash adjuster--due
to the oil escaping through the supply channels--no force is
exerted upon the valve to open or close it until the plunger makes
contact with the base of the housing 536.
[0024] As shown in FIG. 5, the internal axial clearance 560 of the
present invention lash adjuster 502 is selected at a length of
about 0.01 inches to about 0.03 inches, and preferably about 0.02
inches. Therefore, in a failed condition, the valve will begin to
open or close when the valve train is lifted between about 0.01
inches and about 0.03 inches, and preferably about 0.02 inches.
Moreover, as a result of this decreased internal axial clearance
560, in the event of failure, the present invention lash adjuster
502 may be set at the minimum velocity and travel an axial distance
of between about 0.01 inches and about 0.03 inches (preferably
about 0.02 inches) within the lash adjuster 502 body. Thus, when
the lash adjuster 502 fails or momentarily malfunctions, the
plunger 542 only travels between about 0.01 inches to about 0.03
inches, and preferably about 0.02 inches, before it contacts the
base 540 of the housing 536, causing the valve to open.
[0025] When the valve opens between about 0.01 to about 0.03
inches, and preferably about 0.02 inches, there is less damage to
the valve train system in the event of failure than when the valve
opens about 0.1 inches (as in the prior art lash adjuster
arrangement of FIG. 2). Valve actuation depends on what point the
cam is engaging the roller at a given point in time. Thus, the cam
angle determines the valve train lift. Additionally, because of the
select shape of the cam, the steepness of the cam corresponds to
velocity and acceleration of valve opening and closing. Because cam
angle also corresponds to valve velocity and acceleration, there is
a correlation between valve train lift and valve velocity and
acceleration. Thus, the lower the valve train lift when the valve
opens or closes, the lower the opening and closing valve velocity
will be. The lower the opening and/or closing velocity, the less
damage there is to the valve train system.
[0026] For instance, as shown in FIG. 3, when the valve train is
lifted to about 0.03 inches when the valve opens (when the present
invention lash adjuster is functioning properly), the cam rotates
from about 0 degrees (shown at 310) to about 32.5 degrees (shown at
312), and the valve opening velocity gradually increases from about
0 inches/sec (shown at 300) to about 14.44 inches/sec (shown at
314). Similarly, when the valve train is lifted to about 0.03
inches when the valve closes (when the present invention lash
adjuster is functioning properly), the earn rotates from about 158
degrees (shown at 332) to about 180 degrees (shown at 311), and the
valve closing velocity gradually increases from about -20
inches/sec (shown at 328) to 0 inches/sec (shown at 330).
[0027] In a valve train system with a properly functioning lash
adjuster, the increase in valve opening and closing velocities is
gradual. However, unlike the prior art lash adjuster, if the
present invention lash adjuster fails, the change in opening
velocity (shown at 303) and closing velocity (shown at 315) of the
valve remains more gradual. For instance, in a valve train system
having a failed present invention lash adjuster, as the cam rotates
from about 0 degrees (shown at 300) to about 32.5 degrees (shown at
317), the velocity of the valve remains about 0 inches/sec (shown
at 303). When the cam reaches an angle of about 32.5 degrees (shown
at 317), the valve opens at a velocity of only about 14.40
inches/sec (shown between 317 and 314). However, this increase in
velocity is not significantly different from the gradual increase
in velocity when the lash adjuster is working properly. The change
in velocity remains relatively gradual. As a result, the valve gear
is still on the ramp when the valve opens. Therefore, there is
limited stress on the system and damage to the valve train is
avoided.
[0028] Similarly, in a valve train system having a failed present
invention lash adjuster, the valve gradually closes until the cam
is rotated to an angle of about 158.5 degrees, when the valve train
is lifted about 0.03 inches. When the cam reaches an angle of about
158.5 degrees, the valve closes at a velocity of only about -20
inches/see. As the cam rotates from about 158.5 degrees (328) to
about 0 degrees (330), the velocity of the valves remains about 0
inches/sec (shown at 315). However, this increase in velocity is
not significantly different from the gradual increase in velocity
when the lash adjuster is working properly. The change in velocity
remains relatively gradual. As a result, the valve gear is still on
the ramp when the valve closes. Therefore, there is limited stress
on the system and damage to the valve train is avoided.
[0029] Additionally, in a valve train system having a failed
present invention lash adjuster, the opening and closing valve
accelerations remain similar to the opening and closing valve
accelerations when the lash adjuster is working properly. In
contrast to the rapid acceleration rate that the prior art lash
adjuster's failure causes the valve to open at, the valve opening
acceleration rate in a system having a failed present invention
lash adjuster is relatively small and gradual. As shown in FIG. 4,
when the present invention lash adjuster is working properly, as
the cam rotates from about 0 degrees to about 32.5 degrees, the
opening acceleration of the valve correspondingly increases at
gradual rate from about 0 inches/sec.sup.2 (shown at 400) to about
16,00 inches/sec.sup.2 (shown at 405). In contrast to a failed
prior art lash adjuster, which causes the valve opening
acceleration to increase abruptly from about 0 inches/sec.sup.2 to
about 329,900 inches/sec.sup.2 (shown at 404), a failed present
invention lash adjuster only causes the valve opening acceleration
to increase from about 0 inches/sec.sup.2 (shown at 400) to about
78,000 inches/sec.sup.2 (shown at 410). Thus, the opening
acceleration rate of a failed present invention lash adjuster is
not significantly different from the acceleration rate when the
lash adjuster is properly functioning. Similarly, the closing
acceleration rate of a failed present invention lash adjuster is
not significantly different from that when it is working properly.
The valve closing acceleration rate in a system having a failed
present invention lash adjuster decreases from about 107,700
inches/sec.sup.2 (shown at 417) to about 0 inches/sec.sup.2 (shown
at 420), in contrast to decreasing from 19,900 inches/sec.sup.2
(shown at 419) to about 0 inches/sec.sup.2 when it is functioning
properly. As a result, the present invention lash adjuster
minimizes stress on the valve train system in the event of such
failure, thereby avoiding damage.
[0030] Lash adjuster failure may involve the failure or malfunction
of one or more parts of the lash adjuster, such as the ball
retainer, the ball spring, or the engagement between the ball and
seat.
* * * * *