U.S. patent application number 10/897885 was filed with the patent office on 2006-01-26 for hydraulic lash adjuster having a simplified plunger.
Invention is credited to Wayne S. Harris, Timothy W. Kunz, Michael J. Skilling.
Application Number | 20060016405 10/897885 |
Document ID | / |
Family ID | 34982542 |
Filed Date | 2006-01-26 |
United States Patent
Application |
20060016405 |
Kind Code |
A1 |
Harris; Wayne S. ; et
al. |
January 26, 2006 |
Hydraulic lash adjuster having a simplified plunger
Abstract
An improved hydraulic lash adjuster including a cup-shaped
adjuster body, and a plunger assembly disposed within the adjuster
body. The plunger assembly includes a stepped axial bore extending
from a body inner end to a central oil passage opening onto a
hemispherical pivot head. A valve seat for a check valve is
disposed against the step, defining a low-pressure oil chamber in
the axial bore. A check ball and lash adjustment spring are
disposed against the seat in a high-pressure chamber formed between
the valve seat and adjuster body. The body of the plunger assembly
may be formed by inexpensive processes to a length equivalent to
that of a prior art one-piece plunger to resist torsional side
loads which may be imposed on the HLA in use. The separately formed
valve seat may also be used in other hydraulic lash adjusters such
as incorporated in hydraulic valve lifters.
Inventors: |
Harris; Wayne S.; (Hilton,
NY) ; Skilling; Michael J.; (Ada, MI) ; Kunz;
Timothy W.; (Rochester, NY) |
Correspondence
Address: |
Jimmy L. Funke, Esq.;Delphi Technologies, Inc.
Mail Code 480410202
P.O. Box 5052
Troy
MI
48007
US
|
Family ID: |
34982542 |
Appl. No.: |
10/897885 |
Filed: |
July 23, 2004 |
Current U.S.
Class: |
123/90.5 ;
123/90.48 |
Current CPC
Class: |
F01L 1/2405 20130101;
Y10T 137/7927 20150401 |
Class at
Publication: |
123/090.5 ;
123/090.48 |
International
Class: |
F01L 1/14 20060101
F01L001/14 |
Claims
1. A plunger assembly for use in a hydraulic lash adjuster for
eliminating lash in a valve train of an internal combustion engine,
comprising: a) a plunger for sliding within a lash adjuster body,
said plunger including an inner end and an outer end for engaging a
rocker arm of said valve train, wherein an axial bore extends from
said inner end to communicate with said outer end, defining a
low-pressure oil chamber; and b) a separate seat element disposed
in said axial bore at said inner end thereof, wherein said seat
element includes a first beveled annular seat for mating with a
check ball, a first end face in cooperation with a plunger spring,
a second beveled annular seat formed in said element opposite said
first beveled annular seat, and a second end face formed in said
element opposite said first end face such that said element may be
installed into said axial bore with either one of said seats being
positioned to cooperate with said check ball and either one of said
end faces being positioned to cooperate with said plunger
spring.
2. A plunger assembly in accordance with claim 1 further comprising
a port extending through a wall of said plunger for providing oil
to said low-pressure oil reservoir.
3. (canceled)
4. (canceled)
5. A plunger assembly in accordance with claim 1 wherein said seat
element is welded to said plunger.
6. A plunger assembly in accordance with claim 1 wherein said axial
bore is formed by a process selected from the group consisting of
boring, turning, screw-machining, powdered metal forming, and metal
injection molding.
7. A hydraulic lash adjuster for eliminating lash in a valve train
of an internal combustion engine, comprising: a) a lash adjuster
body; b) a plunger assembly slidably disposed in said adjuster
body, said plunger assembly including a plunger having an inner end
and an outer end for engaging said valve train, wherein an axial
bore extends from said inner end of said plunger to communicate
with said outer end, said axial bore defining a low-pressure oil
chamber in said plunger, wherein a separate seat element is
disposed in said axial bore said seat element having a first
beveled annular seat for mating with a check ball, a first end face
in cooperation with a plunger spring, a second beveled annular seat
formed in said element opposite said first beveled annular seat,
and a second end face formed in said element opposite said first
end face, and wherein a high-pressure chamber is formed between
said seat element and said lash adjuster body; c) a check valve for
mating with said seat element to regulate flow of oil from said
low-pressure oil chamber across said seat element into said
high-pressure chamber; and d) a lash adjustment spring disposed
between said lash adjuster body and said plungers wherein said
element may be installed into said axial bore with either one of
said seats being positioned to cooperate with said check ball and
either one of said end faces being positioned to cooperate with
said plunger spring whereby a substantially identical distance
between said lash adjuster body and plunger is maintained.
8. An internal combustion engine including a valve train, the
engine comprising a hydraulic lash adjuster for eliminating lash in
said valve train, said hydraulic lash adjuster including a lash
adjuster body, a plunger assembly slidably disposed in said
adjuster body, said plunger assembly including a plunger having an
inner end and an outer end for engaging said valve train, wherein
an axial bore extends from said inner end of said plunger to
communicate with said outer end, said axial bore defining a
low-pressure oil chamber in said plunger, wherein a separate seat
element is disposed in said axial bore, said seat element having a
first beveled annular seat for mating with a check ball, a first
end face in cooperation with a plunger spring, a second beveled
annular seat formed in said element opposite said first beveled
annular seat, and a second end face formed in said element opposite
said first end face, and wherein a high-pressure chamber is formed
between said seat element and said lash adjuster body, a check
valve for mating with said seat element to regulate flow of oil
from said low-pressure oil chamber across said seat element into
said high-pressure chamber, and a lash adjustment spring disposed
between said lash adjuster body and said plunger, wherein said
element may be installed into said axial bore with either one of
said seats being positioned to cooperate with said check ball and
either one of said end faces being positioned to cooperate with
said plunger spring whereby a substantially identical distance
between said last adjuster body and plunger is maintained.
9. (canceled)
Description
TECHNICAL FIELD
[0001] The present invention relates to hydraulic lash adjusters
for combustion valves of internal combustion engines; more
particularly, to a hydraulic lash adjuster (HLA) wherein a plunger
is operative within an HLA body; and most particularly, to an
improved hydraulic lash adjuster having a simplified long plunger
assembly having the side-loading capability of a one-piece plunger,
with reduced manufacturing complexity and cost.
BACKGROUND OF THE INVENTION
[0002] An HLA generally comprises a plunger slidably disposed
within a cup-shaped body for fixed mounting in an internal
combustion engine, which plunger may be hydraulically extended from
the body to take up mechanical lash in an engine valve train. The
HLA is supplied with low-pressure engine oil for conventional
lubrication and for lash adjustment. A spring in a high-pressure
chamber formed between the plunger and the body urges the plunger
out of the body to take up mechanical lash in the valve train,
thereby expanding the high-pressure chamber. A ball check valve
between the low-pressure reservoir and the high-pressure chamber
allows that chamber to fill with oil, thereby making the HLA
hydraulically rigid. As oil escapes from the high-pressure chamber
by leakage around the plunger, the lost oil is replenished through
the check valve. If the effective length of the valve train
shortens during the engine's cam operating cycle, positive lash is
created and the HLA extends, moving the plunger to a higher
position at the end of the cycle than at the beginning. Inversely,
if the effective length of the valve train lengthens during the cam
cycle, negative lash is created and the lash adjuster contracts,
moving the plunger to a lower position at the end of the cycle than
at the beginning. The latter condition typically occurs when valve
train components lengthen in response to increased temperature.
[0003] A problem exists in some prior art HLA assemblies. A prior
art one-piece plunger has a ball surface at its outer end with a
central opening for supplying oil from the low-pressure reservoir
to the socket end of an associated rocker arm assembly, the
reservoir being supplied via a radial port in a sidewall of the
reservoir. The inner end of the plunger comprises a seat for the
ball check valve. See, for example, FIG. 2 in U.S. Pat. No.
5,642,694.
[0004] Although a one-piece plunger is desirable because it
provides a long bearing surface within the body and hence excellent
stability against side-load forces, forming such a single element
plunger in the prior art is known to be costly and difficult. The
manufacture requires a large investment in equipment such as
cold-forming equipment, making the cost of small production volume
applications prohibitive. Additionally, due to the forming process
required, the resulting plunger tends to have a thin wall section
at its outer ball surface end, a region where thicker walls are
desirable.
[0005] It is more common in the recent prior art to provide an HLA
plunger formed as two shorter sections, each of which may be formed
by relatively inexpensive methods such as boring, turning,
screw-machining, powdered metal forming, and/or metal injection
molding. See, for example, FIG. 1 in U.S. Pat. No. 5,622,147.
[0006] Forming the plunger as upper and lower halves reduces the
cost but at a sacrifice in side-loading stability. Further, the
surfaces forming the joint between the upper and lower halves
benefit from precision grinding to ensure a leak-proof juncture,
again at additional manufacturing cost. In either prior art
example, the seat for the ball check valve is integrally formed in
the lower end of the plunger, a process that adds cost to the
manufacture of the plunger, and a potential source of leakage
across the seated check valve since fine finishing of the seating
surface is difficult to achieve in an integral seat.
[0007] It is a principal object of the present invention to provide
a hydraulic lash adjuster including a plunger that is easier to
manufacture and has a long bearing surface equivalent to the
bearing surface of a prior art one-piece plunger.
SUMMARY OF THE INVENTION
[0008] Briefly described, a hydraulic lash adjuster in accordance
with the invention comprises a hollow adjuster body for fixed
mounting onto an engine, and a plunger assembly disposed within the
hollow body. A plunger body includes a stepped axial bore extending
from an inner end thereof to a central oil passage opening onto a
conventional hemispherical pivot head. A valve seat for a check
valve is disposed against the step, defining thereby a low-pressure
oil reservoir in the axial bore. The plunger body is provided with
an annular collector groove and entrance port for supplying
lash-adjusting oil to the low-pressure reservoir. A check ball and
lash adjustment spring are disposed against the seat in a
high-pressure chamber formed conventionally between the valve seat
the adjuster body. The plunger body may be formed to any desired
length, to provide an outer bearing surface equivalent to that of a
prior art one-piece plunger to resist torsional side loads which
may be imposed on the HLA in use. It is understood that the plunger
body may be formed of induction hardenable steels, nonferrous
metals, or ceramics. The plunger body is readily formed by
inexpensive processes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention will now be described, by way of
example, with reference to the accompanying drawings, in which:
[0010] FIG. 1 is an elevational cross-sectional view of a first
prior art hydraulic lash adjuster having a one-piece plunger
body;
[0011] FIG. 2 is an elevational cross-sectional view of a second
prior art hydraulic lash adjuster having a two .piece plunger body;
and
[0012] FIG. 3 is an elevational cross-sectional view of an improved
hydraulic lash adjuster in accordance with the invention having a
simplified two-piece plunger.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] Referring to FIG. 1, there is shown a prior art hydraulic
lash adjuster, designated generally as 10, which includes a
generally cup-shaped cylindrical adjuster body 12 configured to be
received in an engine cylinder head 14, or other suitable
installation location. The cup-shaped cylindrical body 12 forms a
dash pot for a tubular one-piece plunger 16 configured for sliding
disposition within the bore 18 of the body 12. In the embodiment
shown, the one-piece plunger body 16 includes a semispherically
shaped, upper thrust end 20 which extends out from the body 12 for
engagement with a corresponding, concave portion of a valve train
rocker arm (not shown) in cylinder head 14.
[0014] A plunger return spring 26 is interposed between the bottom
28 of the cup-shaped body 12 and the lower end 30 of plunger 16 and
acts to bias plunger 16 such that contact is maintained with the
spherically concave portion of the rocker arm, thereby eliminating
mechanical lash in the associated valve train. Fluid for the dash
pot of lash adjuster 10 is in the form of oil supplied from the
engine lubricating system to a gallery 32. An external annular
groove 34 in body 12 communicates through port 36 to deliver oil to
annular space 38 defined by inner wall 40 of body 12 and an annular
groove 42 in the outer surface of tubular plunger 16. A second port
46 extends through the plunger wall and provides a means for fluid
communication between annular space 38 and low pressure chamber 48
of plunger 16.
[0015] The lower end of plunger 16 is provided with an outlet port
50 through which oil, stored within low-pressure chamber 48, may
flow into high-pressure chamber 52 defined between the lower end 30
of the plunger 16 and the bottom, closed end 28 of cup-shaped body
12. Flow through outlet port 50 is controlled by a check valve in
the form of a ball 54 which closes against a seat 56 encircling the
lower end of the outlet port 50. A suitable valve cage 58 and valve
return spring 60 limit open travel of valve ball 54 to the amount
necessary to accomplish replenishment of high-pressure chamber 52
with oil which normally escapes therefrom between the sliding
surfaces of tubular plunger 16 and cup-shaped body 12 as
"leak-down". As shown, valve cage 58 is held against plunger 16 by
plunger spring 26.
[0016] Low-pressure chamber 48 of plunger 16 extends substantially
the length of the plunger, from adjacent the outlet port 50 to the
semi-spherical thrust end 20. An opening 62 extends through the
thrust end 20 of plunger 16 to enable oil within low pressure
chamber 48 to lubricate the end of the rocker arm. An integral
baffle 64 is disposed within the low-pressure chamber 48
intermediate the ends of the chamber. The baffle 64 is configured
as an annular shelf which extends radially inwardly from the inner
wall 66 of the low-pressure chamber 48 to define a central opening
68 for the passage of oil from the oil supply port 46 to the outlet
port 50.
[0017] Prior art one-piece plunger 16 thus enjoys an outer bearing
surface length 70 extending virtually the entire depth of bore 18
in HLA body 12.
[0018] Referring to FIG. 2, there is illustrated a prior art
hydraulic lash adjuster 100 having a two-piece plunger,
substantially as disclosed in U.S. Pat. No. 5,622,147 FIG. 1.
Adjuster 100 has a body 102, a plunger assembly 104 defined by an
upper plunger element 106 and a lower plunger element 108 which are
received within the body in close fitting relationship and which
define a low-pressure chamber 110 between them. The bottom 112 of
lower plunger element 108 forms, in cooperation with the end of a
reduced diameter portion 114 of the body bore, a high pressure
chamber 116. A check valve 118 is provided in the end of a passage
120 which connects the high and low pressure chambers. The check
valve, which is shown as a ball but which can be a flat disk or the
like, is retained by a cage 122 which is in interference fit with a
counterbore 124 formed in the lower plunger element and which
provides a seat for the lash adjuster plunger spring 126. In
accordance with the most prevalent design practice, a bias spring
128 acting between the bottom of the cage 122 and the check valve
118 biases the check valve into a normally closed position.
[0019] An oil entry port 130, in communication with engine
lubricating system oil gallery (not shown), opens into the body
bore and intersects a collector groove 132 which intersects a
radial port 134 in the upper plunger element to supply hydraulic
fluid to the chamber 110. A second collector groove 136 and port
138 in the upper plunger element provides metered hydraulic fluid
to an axial bore 140 to supply lubricant to a rocker arm (not
shown) which engages a modified ball end 142 formed on the end of
the upper plunger element, metering being provided by means of a
controlled clearance between the plunger and the bore in the area
of the land between the port 130 and the collector groove 136. The
plunger is retained within the body by means of a cap 144.
[0020] As noted above, dividing the plunger into an upper half 106
and a lower half 108, for the sake of manufacturing ease and
economy, yields a plunger which either a) has an undesirably short
bearing length 170 of the upper half, or b) requires welding
together and machining of the upper and lower halves to provide a
non-divided plunger having a desirably long bearing length, but at
increased manufacturing cost.
[0021] Referring to FIG. 3, a simplified and improved hydraulic
lash adjuster 200 in accordance with the invention includes a
generally cup-shaped cylindrical adjuster body 212 configured to be
received in an engine cylinder head 14 of an internal combustion
engine shown schematically as numeral 15. The cup-shaped
cylindrical body 212 forms a dash pot for a tubular plunger 216
configured for sliding disposition within the bore 218 of the body
212. In the embodiment shown, the plunger 216 includes a
semispherically shaped, upper thrust end 220 which extends out from
the body 212 for engagement with a corresponding, concave portion
of a rocker arm of valve train 213 in cylinder head 14. It is
understood that the plunger body may be formed of induction
hardenable steels, nonferrous metals, or ceramics.
[0022] An axial bore 222 extends the length of plunger 216,
preferably having a reduced diameter portion 224 extending through
upper thrust end 220 for providing oil to the rocker arm. Bore 222
is preferably stepped near the lower end thereof for receiving a
check valve seat element 226 to close bore 222 and form thereby a
low-pressure chamber 228 within plunger 216.
[0023] Seat element 226, in conjunction with tubular plunger 216 to
form plunger assembly 227, is sized for a close fit within bore 222
and may be secured and sealed against bypass leakage as by welding
to plunger 216. Seat element 226 includes an annular beveled seat
230 for receiving a check ball 232 to regulate flow from chamber
228 across seat 230. In a currently preferred embodiment, element
226 is provided with identical beveled seats 230 on opposite sides
thereof such that element 226 does not require specific orientation
for installation into plunger 216. Seat element 226 forms, in
cooperation with the end of a reduced diameter portion 214 of the
body bore, a high pressure chamber 217.
[0024] Check ball 232 is retained by a cage 234 which provides a
seat for the lash adjuster plunger spring 236. A bias spring 238
acting between the bottom of the cage 234 and the check ball 232
biases the check valve into a normally closed position. Valve cage
234 and bias spring 238 limit open travel of valve ball 232 to the
amount necessary to accomplish replenishment of high-pressure
chamber 217 with oil which normally escapes therefrom between the
sliding surfaces of tubular plunger 216 and cup-shaped body 212 as
"leak-down".
[0025] Fluid for the dash pot of lash adjuster 200 is in the form
of oil supplied from the engine lubricating system to a gallery
240, similar to that shown as numeral 32 in FIG. 1. An external
annular groove 242 in body 212 communicates through port 244 to
deliver oil to annular space 246 defined by inner wall 248 of body
212 and an annular groove 250 in the outer surface of tubular
plunger 216. A second port 252 extends through the plunger wall and
provides a means for fluid communication between annular space 246
and low pressure chamber 228 of plunger 216.
[0026] Simplified and improved plunger 216 thus enjoys an outer
bearing surface length 270 extending virtually the entire depth of
bore 218 in HLA body 212, equivalent at least to the length 70 of
bearing surface in prior art one-piece plunger 16 (FIG. 1), and far
longer than the length 170 of bearing surface in prior art upper
plunger element 106 (FIG. 2).
[0027] In the embodiment shown of an HLA, having a separate seat
element 226 allows for, among other things, improved
manufacturability of seat element 226 and the axial bore 222 of
plunger 216. However, it is understood that separate seat element
226, with an associated check ball 232 and cage 234, may be
alternately incorporated into other valve train members having a
lash adjustment feature such as, for example, a hydraulic valve
lifter, thereby allowing for similar improvements in the
manufacturability of the axial bore of the valve train member as
well.
[0028] While the invention has been described by reference to
various specific embodiments, it should be understood that numerous
changes may be made within the spirit and scope of the inventive
concepts described. Accordingly, it is intended that the invention
not be limited to the described embodiments, but will have full
scope defined by the language of the following claims.
* * * * *