U.S. patent application number 13/900892 was filed with the patent office on 2014-11-27 for thermal spray coated engine valve for increased wear resistance.
The applicant listed for this patent is Caterpillar Inc.. Invention is credited to M. Brad Beardsley, Ondrej Racek, Daniel J. Sordelet, Mark D. Veliz.
Application Number | 20140345557 13/900892 |
Document ID | / |
Family ID | 51934090 |
Filed Date | 2014-11-27 |
United States Patent
Application |
20140345557 |
Kind Code |
A1 |
Veliz; Mark D. ; et
al. |
November 27, 2014 |
Thermal Spray Coated Engine Valve for Increased Wear Resistance
Abstract
A valve for use in an internal combustion engine is disclosed.
The valve includes a stem connected to a fillet disposed between
the stem and a seat face. A port receives the stem and accommodates
a seat insert that engages the seat face when the valve is in a
closed position. The seat insert is fabricated from a
non-cobalt-based alloy or an iron-based alloy and the seat face is
coated with a cobalt-based alloy or a nickel-based alloy. The
coating may be applied using a thermal spray process, such as
HVOF.
Inventors: |
Veliz; Mark D.; (Metamora,
IL) ; Sordelet; Daniel J.; (Peoria, IL) ;
Racek; Ondrej; (Yverdon-les-Bains, CH) ; Beardsley;
M. Brad; (Laura, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Caterpillar Inc. |
Peoria |
|
IL |
|
|
Family ID: |
51934090 |
Appl. No.: |
13/900892 |
Filed: |
May 23, 2013 |
Current U.S.
Class: |
123/188.3 ;
427/456 |
Current CPC
Class: |
F01L 3/04 20130101; C23C
4/073 20160101; C23C 4/06 20130101 |
Class at
Publication: |
123/188.3 ;
427/456 |
International
Class: |
F01L 3/04 20060101
F01L003/04; C23C 4/08 20060101 C23C004/08 |
Claims
1. A valve for use in an internal combustion engine, the valve
comprising: a stem connected to a fillet, the fillet connecting the
stem to a seat face; a port that receives the stem and accommodates
a seat insert that engages the seat face when the valve is in a
closed position; the seat insert being fabricated from a
non-cobalt-based alloy; and the seat face being coated with a
cobalt-based alloy or a nickel-based alloy.
2. The valve of claim 1 wherein the cobalt-based alloy covers the
seat face and not the fillet.
3. The valve of claim 1 wherein the seat face is disposed between
the fillet and a margin, the cobalt-based alloy covering the seat
face and not the fillet or the margin.
4. The valve of claim 1 wherein the cobalt-based alloy is coated
onto the seat face using a thermal spray process.
5. The valve of claim 4 wherein the thermal spray process is high
velocity oxygen fuel (HVOF) process.
6. The valve of claim 1 wherein the non-cobalt-based alloy is an
iron-based alloy.
7. The valve of claim 1 wherein the non-cobalt-based alloy is
J130.
8. The valve of claim 1 wherein the nickel-based alloy is a NiCrAlY
alloy.
9. The valve of claim 1 wherein the cobalt-based alloy is
STELLITE.RTM. 1.
10. The valve of claim 1 wherein the cobalt-based alloy is selected
from the group consisting of STELLITE.RTM. 1, STELLITE.RTM. 3,
STELLITE.RTM. 4, STELLITE.RTM. 6, STELLITE.RTM. 6B, STELLITE.RTM.
12, STELLITE.RTM. 21, STELLITE.RTM. 25, STELLITE.RTM. 31,
STELLITE.RTM. 190, STELLITE.RTM. 694, STELLITE.RTM. 706,
STELLITE.RTM. 712, STELLITE.RTM. F, STELLITE.RTM. Star 3,
TRIBALOY.RTM. 400, TRIBALOY.RTM. 400C, TRIBALOY.RTM. 800,
TRIBALOY.RTM. 900 and combinations thereof.
11. The valve of claim 1 wherein the cobalt-based alloy is
STELLITE.RTM. 1 and the iron-based alloy is J130.
12. The valve of claim 1 wherein the cobalt-based alloy is coated
onto the seat face with a thickness ranging from about 0.05 mm to
about 2 mm.
13. An internal combustion engine including the valve as defined in
claim 1.
14. An internal combustion engine, comprising: a cylinder block
including at least one combustion chamber; at least one air intake
leading into the least one combustion chamber and defining a port
configured to receive a valve; the valve positioned within the at
least one port for selectively opening and closing the port, the
valve including a stem connected to a fillet that is connects the
stem to a seat face, the seat face being coated with a cobalt-based
alloy or a nickel-based alloy; and the port accommodating a seat
insert, the seat insert being fabricated from an iron-based
alloy.
15. The engine of claim 14 wherein the nickel-based alloy is a
NiCrAlY alloy.
16. The engine of claim 14 wherein the seat face is coated using a
thermal spray process.
17. The engine of claim 14 wherein the cobalt-based alloy is
selected from the group consisting of STELLITE.RTM. 1,
STELLITE.RTM. 3, STELLITE.RTM. 4, STELLITE.RTM. 6, STELLITE.RTM.
6B, STELLITE.RTM. 12, STELLITE.RTM. 21, STELLITE.RTM. 25,
STELLITE.RTM. 31, STELLITE.RTM. 190, STELLITE.RTM. 694,
STELLITE.RTM. 706, STELLITE.RTM. 712, STELLITE.RTM. F,
STELLITE.RTM. Star 3, TRIBALOY.RTM. 400, TRIBALOY.RTM. 400C,
TRIBALOY.RTM. 800, TRIBALOY.RTM. 900 and combinations thereof.
18. The engine of claim 14 wherein the cobalt-based alloy is
STELLITE.RTM. 1 and the non-cobalt based alloy is J130.
19. The engine of claim 14 wherein the cobalt-based alloy is coated
onto the seat face with a thickness ranging from about 0.05 mm to
about 2 mm.
20. A method of improving the durability of an engine valve,
comprising: providing a valve including a stem connected to a
fillet that connects the stem to a seat face; providing an engine
port for receiving the stem, wherein the port accommodates an
iron-based seat insert that engages the seat face when the valve is
in a closed position; and thermal spray coating the seat face with
a cobalt-based alloy or a NiCrAlY alloy.
Description
TECHNICAL FIELD
[0001] This disclosure relates to valves coated with a
wear-resistant thermal spray coating and internal combustion
engines incorporating the same.
BACKGROUND
[0002] Internal combustion engines are used in many different
applications. For example, intake valves of such engines are
positioned in an intake port disposed between the air intake and
the combustion chamber. During an air intake stroke, a cam or
rocker arm pushes the intake valve open and allows the fuel mixture
to enter the combustion chamber. Further, exhaust valves are
positioned in an exhaust port disposed between the combustion
chamber and an exhaust flow passage. During an exhaust stroke, the
cam or rocker arm pushes the exhaust valve open and combustion
gases are expelled from the chamber.
[0003] The seal that the valve makes with the port is important to
engine performance and efficiency. If the valve leaks, the pressure
in the combustion chamber decreases and the engine generates
considerably less power. Engine manufacturers over the last few
decades have dedicated substantial efforts in designing valves that
can form a tight seal between the seat insert of the port and the
seating face or the seat face of the fillet.
[0004] Both the seat insert and the seat face are important for the
reliability of the valve. For example, it is well-known that
corrosion or wear of either the seat insert or seat face can cause
the valve to leak when the valve is closed, which results in "burn
through." To prevent burn through, the seat insert and the seat
face on the valve fillet have been made with increasingly harder
materials that are also corrosion resistant.
[0005] The seat face may be hardened by applying a hard cladding
layer followed by machining to form the seat face with the desired
dimensions. The hard cladding makes the seat face more
wear-resistant. Hard cladding can also reduce the formation of dent
marks. Examples of materials that are frequently used for seat face
materials are metal alloys having cobalt and nickel. As an
alternative to applying hard cladding to the seat face, hard
cladding may also be applied to seat inserts. Because of the high
cost, hard cladding is typically not applied to both the seat
insert and the seat face. Regardless, in almost all cases, the
advantages of using hard cladding for either the seat insert or the
seat face may not be sufficient to offset the increase in price
over softer metals such as iron-based alloys.
[0006] While hardened seat faces last longer, the means by which
the seat faces are hardened is problematic. Specifically, plasma
transferred arc (PTA) cladding, also known in the art as hard
facing, is routinely used on valves in the engine manufacturing
industry. Unfortunately, PTA cladding requires that the deposition
of a thick layer and high heat input, which causes the base
material of the valve to degrade because of microstructural
degradation or from residual stress. As a result, there is an
increased tendency for fatigue failures. To improve the durability
of seat inserts disposed in the port, additional nitriding or
thin-film coatings have been used. Nitriding is typically not an
option for outlet or exhaust ports as the alloys used for the
outlet ports are not responsive to nitriding.
[0007] Cobalt-based materials have been used to coat seat inserts
as well as seat faces via PTA cladding. It is widely recognized in
the art that if a cobalt-based material is used to coat the seat
face, a cobalt material may be used to coat the seat insert for
improved performance. In other words, it is widely recognized that
cobalt based materials, when used as wear-resistant coatings, may
be "self-mated," or both parts that engage one another should be
coated with cobalt-based materials. However, cobalt-based materials
may be expensive and using a cobalt-based material to clad the seat
face and/or to coat the seat insert may result in a costly
assembly.
[0008] When wear occurs on the seat face or the seat insert of an
automobile or truckvalve, the geometry and the gap between the stem
and the rocker are no longer optimized, and therefore adjustments
need to be made, which are referred to as lash adjustments.
Performing lash adjustments manually requires a vehicle to be taken
out of service, which is an expense and a nuisance to the operator.
Some vehicles are equipped with hydraulic lash adjusters (HLA or
lifters or tappets) that automatically adjust the gap between the
stem tip and the rocker to maintain proper sealing and seating
velocities. Heavy-duty diesel engines do not typically have HLA
because of the high valve train loads. Therefore, lash adjustments
for most heavy duty diesel engines must be made manually, thereby
requiring the machine to be taken out of service.
[0009] Thus, there is a need for improved seat faces and as seat
inserts that are cost-effective and that provide sufficient wear
resistance to extend the time between lash resets.
SUMMARY
[0010] In one aspect, a valve for use in an internal combustion
engine is disclosed. The valve may include a stem connected to a
fillet that connects the stem to a seat face. The stem may be
received in a port that accommodates a seat insert that engages the
seat face when the valve is in a closed position. The seat insert
may be fabricated from a non-cobalt-based alloy and the seat face
may be coated with a cobalt-based alloy or a nickel-based
alloy.
[0011] In another aspect, an internal combustion engine is
disclosed. The engine may include a cylinder block that may include
at least one combustion chamber. The engine may further include at
least one passage in communication with to the at least one
combustion chamber and defining a port configured to receive a
valve. The valve may be positioned within the port for selectively
opening and closing the port. The valve may include a stem
connected to a fillet that connects the stem to a seat face. The
seat face may be coated with a cobalt-based alloy or a nickel-based
alloy. Further, in the case of an intake valve, the port may
accommodate a seat insert. The seat insert may be fabricated from
an iron-based alloy.
[0012] In yet another aspect, a method of improving the durability
of an engine valve is disclosed. The method may include providing a
valve that may include a stem connected to a fillet that connects
the stem to a seat face. The method may further include providing
an engine port for receiving the stem and the seat face when the
valve is in a closed position. In the case of an intake valve, the
port may accommodate an iron-based seat insert that engages the
seat face when the valve is in the closed position. The method may
further include thermal spray coating the seat face with a
cobalt-based alloy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a front plan view of a disclosed valve.
[0014] FIG. 2 is a partial sectional view of a disclosed internal
combustion engine showing a disclosed valve in a closed position
and in contact with a port disposed between an air intake and a
combustion chamber.
[0015] FIG. 3 is an enlarged partial view of the contact between a
seat insert that is accommodated in the port shown in FIG. 2 and
the seat face shown in FIGS. 1-2.
[0016] FIG. 4 graphically illustrates the improved wear performance
of cobalt-based alloys (STELLITE.RTM. 6, TRIBALOY.RTM. T-400 and
STELLITE.RTM. 1) versus other cobalt-based and non-cobalt-based
alloys shown to the left in FIG. 4 (TRIBALOY.RTM. T-800, CoNiCrAlY,
NiCrAlY) at an operating temperature of 800.degree. C.
[0017] FIG. 5 graphically illustrates the improved performance of
cobalt-based alloys (STELLITE.RTM. 6, TRIBALOY.RTM. T-400 and
STELLITE.RTM. 1) versus other cobalt-based and non-cobalt based
alloys (TRIBALOY.RTM. T-800, CoNiCrAlY, NiCrAlY) when used to coat
a seat face on a fillet of a valve operating at a temperature of
550.degree. C.
[0018] FIG. 6 illustrates, graphically, the improved total wear
performance of STELLITE.RTM. 1 versus TRIBALOY.RTM. 400, a NiCrAlY
alloy and no seat face coating at all as well as the improved
performance of the iron-based alloy J130 for the seat insert versus
the iron-based alloy J10. Further, FIG. 6 also illustrates the
increased wear that occurs at an operating temperature of
800.degree. C. versus an operating temperature of 550.degree.
C.
[0019] FIG. 7 illustrates, graphically, the improved percent valve
wear performance of STELLITE.RTM. 1 versus TRIBALOY.RTM. 400, a
NiCrAlY alloy and no seat face coating at all as well as the
improved performance of the iron-based alloy J130 for the seat
insert versus the iron-based alloy J10. Further, FIG. 7 also
illustrates the increased wear that occurs at an operating
temperature of 800.degree. C. versus an operating temperature of
550.degree. C.
[0020] FIG. 8 illustrates, graphically, the improved performance of
using a thermal spray coating process (HVOF) versus a cladding
process (PTA) for STELLITE.RTM. 1 for coating the seat face as well
as no coating at all at an operating temperature of 550.degree. C.
and using the iron based alloy J3 for the seat insert.
[0021] FIG. 9 illustrates, graphically, the improved performance of
thermal spray coating (HVOF) STELLITE.RTM. 1 on the seat face
versus using a cladding process (PTA) and comparing the performance
of J3 versus J130 as the seat inserts for HVOF applied
STELLITE.RTM. 1 at an operating temperature of 800.degree. C.
[0022] FIG. 10 is a photograph of a seat face coated with a
cobalt-based alloy via a thermal spray process (e.g., HVOF).
[0023] FIG. 11 is a photograph of a cobalt-based alloy that has
been applied to a seat insert via a cladding process (e.g.,
PTA).
DESCRIPTION
[0024] FIG. 1 illustrates a valve 20, that may serve as an intake
valve or an exhaust valve. The valve 20 may include a stem 21 that
may be connected to a fillet 22. The fillet 22 may connect the stem
21 to a seat face 23. The seat face 23 may be disposed between the
fillet 22 and a margin 24. The margin 24 may be disposed between
the seat face 23 and a combustion face 19.
[0025] Turning to FIG. 2, one valve 20 may be installed in a
cylinder head 25 that may define an air intake 26 that terminates
at an intake port 27. The intake port 27 may lead to a combustion
chamber 28, which may slidably accommodate a piston 29 (only
partially shown in FIG. 2). The valve 20 may be biased into the
closed position shown in FIG. 2 by a spring or other biasing
element 31. The stem 21 may extend upward through said biasing
element 31 to be engaged by an actuator in the form of a rocker arm
or cam (not shown in FIG. 2). As shown in FIG. 2, the seat face 23
may engage a seat insert 32 in the closed position. As noted above,
it is important to reduce the wear incurred by the seat face 23
and/or the seat insert 32 to extend the time between lash resets.
An enlarged view of the contact between the seat insert 32 and a
coating 33 disposed on the seat face 23 is shown in FIG. 3. Also
shown in FIG. 2 is another valve 20' installed in the cylinder head
25 that also defines an exhaust passage 41 and an exhaust port 42.
Typically, the exhaust port 42 will not be equipped with a seat
insert 32. However, the the valve 20' may also include a seat face
23' that may be coated in a manner similar to the seat face 23 of
the valve 20.
[0026] As noted above, it is widely recognized that seat faces and
seat inserts or cobalt-based wear resistant coatings on seat faces
and seat inserts perform well when they are "self-mated" or when
both mating components (i.e., a seat insert and a seat face) are
either made from the same cobalt-based alloy or similar
cobalt-based alloys or coated with the same cobalt-based coating or
similar cobalt-based coatings. However, surprisingly, it has been
found that a cobalt-based alloy may be used for the coating 33 on
the seat face 23 while the seat insert 32 may be fabricated from a
non-cobalt-based alloy or a non-cobalt based alloy may be used for
the coating 33 on the seat face 23 while the seat insert 32 may be
fabricated from a non-cobalt-based alloy, such as an iron-based
alloy. Further, it has been found that nickel chromium aluminum
yttrium (NiCrAlY) may also be used for the coating 33 on the seat
face 23 and still provide good wear resistance when the seat insert
is fabricated from a cobalt-based alloy or a non-cobalt-based alloy
such as an iron-based alloy. The seat face 23' may also be coated
with either a cobalt-based coating or a non-cobalt based alloy.
[0027] The data graphically illustrated in FIGS. 4-5 was attained
using a seat insert 32 made from a cobalt-based alloy, J3,
available from L. E. Jones Company (www.lejones.com/). In FIG. 4,
the operating temperature or the temperature to the combustion face
19 (FIG. 1) was 800.degree. C. The left column of FIG. 4 serves as
a base line as the seat face 23 was uncoated and therefore the left
column recites the alloy used to make the valve, PYROMET.RTM. 31V
(P31V), which is an iron-based alloy (www.cartech.com). The other
six alloys that were tested for wear in FIGS. 4-5 include:
TRIBALOY.RTM. T-800 (T-800), which is a cobalt based alloy
manufactured by Deloro Stellite (www.steliite.com); a cobalt nickel
chromium aluminum yttrium alloy sold under the trademark
DIAMALLOY.RTM. 4700 (CoNiCrAlY), manufactured by Sulzer Metco; a
nickel chromium aluminum yttrium alloy sold under the designation
NI343 by Praxair (NiCrAlY); STELLITE.RTM. 6, another cobalt based
alloy; TRIBALOY.RTM. T-400 (T-400), another cobalt based alloy; and
STELLITE.RTM. 1, which is another cobalt based alloy. Thus, the
only non-cobalt based alloy evaluated in FIGS. 4-5 are the NiCrAlY
alloy (NI343) and the P31V, the iron-based alloy used to fabricate
the valve. All of the alloys used for a coating on the seat face
were coated using an HVOF thermal spray process except, of course,
the uncoated valve shown at the left in FIGS. 4-5, which leaves
exposed P31V, the iron-based alloy used to fabricate the valve.
[0028] At 800.degree. C. operating temperature, the cobalt-based
alloy, STELLITE.RTM. 1 exhibited the least amount of wear after 200
hours of operation. Similarly, at an operating temperature of
550.degree. C. and after 200 hundred hours of operation, the
STELLITE.RTM. 1, TRIBALOY.RTM. 400, TRIBALOY.RTM. 800 and the
NiCrAlY (NI343) alloys all performed the best, when used with the
cobalt-based insert (J3). The results for the NiCrAlY alloy are
surprising because, as noted above, it is well known in the art
that cobalt-based alloys show better wear results when the two wear
surfaces are fabricated from the same alloy or the same type of
alloy (i.e., both wear surfaces are fabricated from the same or
different cobalt-based alloys or are "self-mated").
[0029] In another test graphically illustrated in FIGS. 6-7, the
seat insert material was changed to another L.E. Jones cobalt-based
alloy J10 and an iron-based alloy J130. As shown in FIG. 6, the
cobalt-based alloy, STELLITE.RTM. 1 had less wear then the
TRIBALOY.RTM. 400 and NiCrAlY (NI343) alloys, although the NiCrAlY
(NI343) and TRIBALOY.RTM. 400 alloys did very well. Further, it
appears that the non-cobalt, iron-based J130alloy performed
slightly better than the J10 alloy, which is surprising as J130 is
an iron-based alloy, which worked very well with STELLITE.RTM. 1, a
cobalt-based alloy. FIG. 6 graphically illustrates the total wear
while FIG. 7 graphically illustrates the percentage of valve wear.
In FIG. 7, STELLITE.RTM. 1 performed better than TRIBALOY.RTM. 400,
NiCrAlY, and the insert alloys, J10 and J130 performed comparably.
FIGS. 6-7 show that the STELLITE.RTM. 1 as a seat face coating, an
inexpensive cobalt-based alloy, does not need to be matched with a
seat insert fabricated from or coated with a cobalt-based alloy.
Further, FIGS. 6-7 show that the combination of the iron-based J130
alloy for the seat insert and STELLITE.RTM. 1 as the coating for
the seat face provide excellent wear resistance results.
[0030] Turning to FIGS. 8-9, the use of a STELLITE.RTM. 1 coating
deposited via a thermal spray process (HVOF) or a cladding process
(PTA) was compared at 550.degree. C. (FIG. 8) and at 800.degree. C.
(FIG. 9). The seat insert was made from the J3 cobalt-based alloy,
except where noted in FIG. 9. The tests were carried out over a 200
hour period. Surprisingly, at 800.degree. C., the use of cladding
(PTA) proved to be inferior to no coating at all. In any event, the
application of STELLITE.RTM. 1 by HVOF was far superior to the
cladding method (PTA). At 800.degree. C., a further improvement was
made using the iron-based J130 alloy for the insert instead of the
cobalt-based J3 seat insert, which is surprising given the fact
that STELLITE.RTM. 1 is a cobalt-based alloy. Thus, an effective
combination is the application of a wear resistant coating in the
form of STELLITE.RTM. 1 alloy applied to the seat face via a
thermal spray process, such as HVOF, or another thermal spray
process as will be apparent to those skilled in the art. Further,
an effective combination is the STELLITE.RTM. 1 alloy for the
protective coating on the seat face 23 and the use of the
iron-based alloy J130 for the seat insert 32.
[0031] Finally, turning to FIGS. 10-11, the wear resistant coating
33 was applied to the seat face 23 shown in FIG. 10 via a thermal
spray process, such as HVOF. The thickness of the coating 33 may
range from about 0.05 mm to about 2 mm.
[0032] In contrast, a cladding process (PTA) was used to harden the
seat face 23 in FIG. 11 and the degradation of the base material of
the valve 20 is clearly shown which may explain, in part, the poor
performance of the PTA treated seat face at the 800.degree. C.
operating temperature as shown in FIG. 9.
INDUSTRIAL APPLICABILITY
[0033] Improved valves for internal combustion engines are
provided. The valves may include a stem connected to a fillet. The
fillet may be disposed between the stem and a seat face that is
coated with a cobalt-based alloy or a NiCrAlY alloy. While
cobalt-based seat face coatings in combination with readily
available iron-based alloy seat inserts provide superior
performance, NiCrAlY alloys may provide a lower cost alternative
although the wear resistant properties of NiCrAlY alloys may be
somewhat inferior to the cobalt-based alloys, particularly
STELLITE.RTM. 1, TRIBALOY.RTM. 400 and TRIBALOY.RTM. 800. The seat
inserts which engage the seat face disposed on the fillet may be
made of readily-available iron based alloys as discussed above. The
result is an improved valve that is both cost effective and
provides excellent wear resistance.
* * * * *