U.S. patent application number 11/759690 was filed with the patent office on 2008-12-11 for power output in hydraulic systems.
This patent application is currently assigned to ROHMAX ADDITIVES GMBH. Invention is credited to Steven Neil Herzog, Christian Daniel Georges NEVEU, Douglas G. Placek.
Application Number | 20080302422 11/759690 |
Document ID | / |
Family ID | 39406140 |
Filed Date | 2008-12-11 |
United States Patent
Application |
20080302422 |
Kind Code |
A1 |
NEVEU; Christian Daniel Georges ;
et al. |
December 11, 2008 |
POWER OUTPUT IN HYDRAULIC SYSTEMS
Abstract
The power output of a hydraulic system is improved by operating
the hydraulic system with a hydraulic fluid having a VI of at least
130.
Inventors: |
NEVEU; Christian Daniel
Georges; (Santeny, FR) ; Placek; Douglas G.;
(Yardley, PA) ; Herzog; Steven Neil; (Glen Mills,
PA) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
ROHMAX ADDITIVES GMBH
Darmstadt
DE
|
Family ID: |
39406140 |
Appl. No.: |
11/759690 |
Filed: |
June 7, 2007 |
Current U.S.
Class: |
137/3 ;
180/339 |
Current CPC
Class: |
C10M 171/02 20130101;
C10N 2020/04 20130101; C10N 2030/02 20130101; C10M 2209/0863
20130101; C10M 2209/1045 20130101; C10N 2040/08 20130101; C10M
2205/04 20130101; C10M 2205/173 20130101; C10M 2205/02 20130101;
C10M 2205/0206 20130101; C10M 2207/401 20130101; C10M 2209/103
20130101; C10M 2223/00 20130101; Y10T 137/0329 20150401; C10M
2207/2805 20130101; C10M 2203/1025 20130101; C10M 2209/0845
20130101; C10M 2223/0405 20130101; C10N 2030/00 20130101; C10M
2209/086 20130101; C10M 2207/28 20130101; C10M 2207/283 20130101;
C10M 2209/084 20130101; C10M 2203/1006 20130101; C10M 2207/282
20130101; C10M 2205/02 20130101; C10M 2209/08 20130101; C10M
2209/103 20130101; C10M 2209/108 20130101 |
Class at
Publication: |
137/3 ;
180/339 |
International
Class: |
C10M 107/28 20060101
C10M107/28 |
Claims
1. A method of improving a power output of a hydraulic system,
comprising: operating said hydraulic system with a hydraulic fluid
having a VI of at least 130.
2. The method according to claim 1, wherein said power output is
increased at least 3% compared to the power output of a hydraulic
system using a monograde hydraulic fluid having a VI of about 100,
operating at the same pressure and temperature with identical
mechanical power input from the engine or electric motor.
3. The method according to claim 1, wherein said power output is
increased at least 5% compared to the power output of a hydraulic
system using a monograde hydraulic fluid having a VI of about 100,
operating at the same pressure and temperature with identical
mechanical power input from the engine or electric motor.
4. A method of improving a volume output of a hydraulic system,
comprising: operating said hydraulic system with a hydraulic fluid
having a VI of at least 130; wherein the volume output of said
hydraulic system is increased compared to the volume output of a
system using a monograde hydraulic fluid having a VI of about 100,
operating at the same pressure and temperature with identical
mechanical power input from the engine or electric motor.
5. The method according to claim 4, wherein the volume output is
increased at least 3%.
6. The method according to claim 4, wherein the volume output is
increased at least 5%.
7. The method according to claim 1, wherein a constancy of the
power output is increased.
8. The method according to claim 1, wherein a constancy of the
power output is increased at the maximum load.
9. The method according to claim 7, wherein the drop of the power
output after at least 10 minutes of operating time is at most 3%,
measured at a load of 90% of the maximum load or more of a unit
providing mechanical energy.
10. The method according to claim 1, wherein the engine speed of a
unit providing mechanical energy is maintained at a constant rate
and the system delivers an increased level of hydraulic power.
11. The method according to claim 1, wherein the pressure provided
by a unit providing hydraulic power is in the range of 50 to 700
bar.
12. The method according to claim 1, wherein the pressure provided
by a unit providing hydraulic power is in the range of 150 to 350
bar.
13. The method according to claim 1, wherein the hydraulic system
is designed to operate at a lower pressure, such that the output
power is equivalent to that delivered by a reference system using a
hydraulic fluid with a VI of 100.
14. The method according to claim 1, wherein the hydraulic system
demonstrates an improvement in the ratio of hydraulic power output
to power input, such that the ratio of power output/power input is
improved by at least 3%, compared to that delivered by a reference
system using a hydraulic fluid with a VI of 100.
15. The method according to claims 1, wherein the hydraulic fluid
has a VI of at least 150.
16. The method according to claim 1, wherein the hydraulic fluid
has a VI of at least 180.
17. The method according to claim 1, wherein the hydraulic fluid is
a NFPA double viscosity grade, triple viscosity grade, quadra
viscosity grade, or penta viscosity grade hydraulic fluid.
18. The method according to claim 1, wherein the hydraulic fluid is
obtained by mixing a base fluid and a polymeric viscosity index
improver.
19. The method according to claim 1, wherein the hydraulic fluid
comprises at least 60% by weight of at least one base fluid.
20. The method according to claim 1, wherein the hydraulic fluid
comprises at least 60% by weight of at least one base fluid having
a viscosity index of 120 or less.
21. The method according to claim 1, wherein the hydraulic fluid
comprises a member selected from the group consisting of a mineral
oil, a synthetic oil and mixtures thereof.
22. The method according to claim 1, wherein the hydraulic fluid
comprises an API group I oil, API group II oil, API group III oil,
a API group IV oil, API group V oil, a Fischer-Tropsch (GTL)
derived oil or mixtures thereof.
23. The method according to claim 1, wherein the hydraulic fluid
comprises a polyalphaolefin, a carboxylic ester, a vegetable ester,
a phosphate ester, a polyalkylene glycol or mixtures thereof.
24. The method according to claim 1, wherein the hydraulic fluid
comprises at least one polymer.
25. The method according to claim 24, wherein the polymer comprises
polymerized units from monomers selected from the group consisting
of acrylate monomers, methacrylate monomers, fumarate monomers,
maleate monomers and mixtures thereof.
26. The method according to claim 1, wherein the hydraulic fluid
comprises a polyalkylmethacrylate polymer.
27. The method according to claim 1, wherein the hydraulic fluid
comprises a polymer obtained by polymerizing a mixture of
olefinically unsaturated monomers, which comprises a) 0-100 wt % of
one or more ethylenically unsaturated ester compounds of formula
(I) based on the total weight of the ethylenically unsaturated
monomers: ##STR00006## wherein R is hydrogen or methyl, R.sup.1 is
a linear or branched alkyl residue with 1-6 carbon atoms, R.sup.2
and R each independently represent hydrogen or a group of the
formula COO', wherein R' is hydrogen or an alkyl group with 1-6
carbon atoms, b) 0-100 wt % of one or more ethylenically
unsaturated ester compounds of formula (II) based on the total
weight of the ethylenically unsaturated monomers: ##STR00007##
wherein R is hydrogen or methyl, R.sup.4 is a linear or branched
alkyl residue with 7-40 carbon atoms, R.sup.5 and R.sup.6
independently are hydrogen or a group of the formula --COOR',
wherein R'' is hydrogen or an alkyl group with 7-40 carbon atoms,
c) 0-50 wt % of comonomers based on the total weight of the
ethylenically unsaturated monomers.
28. The method according to claim 24, wherein the polymer is
obtained by a polymerization in a API group II mineral oil or API
group III mineral oil.
29. The method according to claim 24, wherein the polymer is
obtained by a polymerization in a polyalphaolefin.
30. The method according to claim 24, wherein the polymer is
obtained by polymerizing a dispersant monomer.
31. The method according to claim 24, wherein the polymer is
obtained by polymerizing a vinyl monomer containing an aromatic
group.
32. The method according to claim 24, wherein the polymer has a
weight average molecular weight in the range of 10000 to 200000
g/mol.
33. The method according to claim 1, wherein the hydraulic fluid
comprises 0.5 to 40% by weight of a polymer.
34. The method according to claim 1, wherein the hydraulic fluid
comprises 3 to 20% by weight of a polymer.
35. The method according to claim 24, wherein the hydraulic fluid
comprises at least two polymers having a different monomer
composition.
36. The method according to claim 35, wherein at least one of the
polymers is a polyolefin.
37. The method according to claim 36, wherein at least one of the
polymers comprises units derived from at least one alkyl ester
monomer.
38. The method according to claim 37, wherein a weight ratio of the
polyolefin and the polymer comprising units derived from at least
one alkyl ester monomer is in the range of 1:10 to 10:1.
39. The method according to claim 1, wherein the hydraulic fluid
comprises an oxygen containing compound selected from the group
consisting of carboxylic acid esters, polyether polyols,
organophosphorus compounds and mixtures thereof.
40. The method according to claim 39, wherein the oxygen containing
compound is a carboxylic ester containing at least two ester
groups.
41. The method according to claim 39, wherein the oxygen containing
compound is a diester of a carboxylic acid containing 4 to 12
carbon atoms.
42. The method according to claim 39, wherein the oxygen containing
compound is an ester of a polyol.
43. The method according to claim 1, wherein the hydraulic fluid
has an ISO viscosity grade in the range of 15 to 150.
44. The method according to claim 1, wherein the hydraulic fluid is
used at a temperature in the range of -40.degree. C. to 120.degree.
C.
45. The method according to claim 1, wherein the hydraulic fluid
comprises a member selected from the group consisting of
antioxidants, antiwear agents, corrosion inhibitors, defoamers and
mixtures thereof.
46. The method according to claim 1, wherein said hydraulic system
is a military hydraulic system, a hydraulic launch assist system
for hydraulic hybrid vehicle propulsion, an industrial hydraulic
system, marine hydraulic system, mining hydraulic system, mobile
equipment hydraulic system or combinations thereof.
47. The method according to claim 1, wherein said hydraulic system
comprises at least one unit providing mechanical energy, at least
one unit that converts mechanical energy into hydraulic power, at
least one pipe for transmitting hydraulic fluid under pressure and
at least a unit that converts the hydraulic power of the hydraulic
fluid into mechanical work.
48. The method according to claim 47, wherein the unit providing
mechanical energy comprises a combustion engine.
49. The method according to claim 47, wherein the unit converting
mechanical energy into hydraulic power is a vane pump.
50. The method according to claim 47, wherein the unit converting
mechanical energy into hydraulic power is a piston pump.
51. The method according to claim 47, wherein the unit converting
mechanical energy into hydraulic power is a gear pump.
52. A hydraulic system, comprising: a hydraulic fluid having a VI
of at least 130; wherein a power output of said hydraulic system is
increased at least 3% compared to the power output of a hydraulic
system using a monograde hydraulic fluid having a VI of about 100,
operating at the same pressure and temperature with identical
mechanical power input from the engine or electric motor; wherein
said hydraulic system is a military hydraulic system, a hydraulic
launch assist system for hydraulic hybrid vehicle propulsion, an
industrial hydraulic system, marine hydraulic system, mining
hydraulic system, mobile equipment hydraulic system or combinations
thereof.
53. A hydraulic system, comprising: a hydraulic fluid having a VI
of at least 130; wherein a power output of said hydraulic system is
increased at least 3% compared to the power output of a hydraulic
system using a monograde hydraulic fluid having a VI of about 100,
operating at the same pressure and temperature with identical
mechanical power input from the engine or electric motor; wherein
said hydraulic system comprises at least one unit providing
mechanical energy, at least one unit that converts mechanical
energy into hydraulic power, at least one pipe for transmitting
hydraulic fluid under pressure and at least a unit that converts
the hydraulic power of the hydraulic fluid into mechanical
work.
54. The hydraulic system according to claim 53, wherein the unit
providing mechanical energy comprises a combustion engine.
55. The hydraulic system according to claim 53, wherein the unit
converting mechanical energy into hydraulic power is a vane
pump.
56. The hydraulic system according to claim 53, wherein the unit
converting mechanical energy into hydraulic power is a piston
pump.
57. The hydraulic system according to claim 53, wherein the unit
converting mechanical energy into hydraulic power is a gear pump.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to the increase of power
output in hydraulic pumps and motors, achieved by the use of
hydraulic fluids with high viscosity index. Use of such fluids can
increase the power output of the system without any modification of
the hardware.
[0003] 2. Description of the Related Art
[0004] Hydraulic systems are designed to transmit energy and apply
large forces with a high degree of flexibility and control. It is
desirable to build systems that efficiently convert input energy
from an engine, electric motor, or other source into usable work.
Hydraulic power can be used to create rotary or linear motion, or
to store energy for future use in an accumulator. Hydraulic systems
provide a significantly more accurate and adjustable means to
transmit energy than electrical or mechanical systems. In general,
hydraulic systems are reliable, efficient, and cost effective,
leading to their wide use in the industrial world. The fluid power
industry is constantly improving the cost effectiveness of
hydraulic systems by employing new mechanical components and
materials of construction.
[0005] Water and many other liquids can be utilized to make
practical use of Pascal's Law, which states that a fluid compressed
in a closed container will transmit the resulting pressure
throughout the system undiminished and equal in all directions.
[0006] Standard "HM" monograde oil is typically selected as it is
the lowest cost option and has a long history of dependable
performance with no maintenance issues. Outdoor applications of
fluid power that experience wide variations in temperature will
make use of lower viscosity grade fluids in the winter and higher
viscosity grade fluids in the summer. Some hydraulic fluids are
formulated with PAMA additives as viscosity index improvers, in
order to achieve good low temperature fluidity properties under
cold start-up conditions ("HV" grade oils). PAMA additives are not
known to offer any other performance benefits.
[0007] E.g., the document WO 2005108531 describes the use of
hydraulic fluids comprising PAMA additives in order to reduce the
temperature increase of a hydraulic fluid under work load. However,
an improvement with regard to power output is not indicated or
suggested by that document.
[0008] Additionally, the document WO 2005014762 discloses a
functional fluid having an improved fire resistance. The fluid can
be used in hydraulic systems. However, the document is silent with
regard to the power output of the system using such a fluid.
[0009] Achieving higher power output in a hydraulic system is
typically achieved by selecting a larger pump, or by other hardware
construction improvements of the unit providing mechanical energy
to the hydraulic system. However, such an approach is usually
connected with higher energy consumption and increased cost.
[0010] A further common object of the background art is the
improvement of the volume output. According to background art,
these objects are conventionally achieved by a combustion engine or
an electric motor having more power. However, such approach is
usually connected with higher energy consumption and increased
cost, and is often constrained by space or weight limitations.
SUMMARY OF THE INVENTION
[0011] Taking into consideration the background art, it is an
object of the present invention to provide hydraulic systems having
increased power output in order to facilitate increased work loads
and improved productivity. Increased power output can be used to
generate increased digging force, lifting capacity, or machine
speed. Furthermore, it is an object of the present invention to
improve the lifetime and the service interval of the hydraulic
system.
[0012] These and other objects have been achieved by the present
invention the first embodiment of which includes a method of
improving a power output of a hydraulic system, comprising:
[0013] operating said hydraulic system with a hydraulic fluid
having a VI of at least 130.
[0014] In another embodiment, the present invention relates to a
method of improving a volume output of a hydraulic system,
comprising:
[0015] operating said hydraulic system with a hydraulic fluid
having a VI of at least 130;
[0016] wherein the volume output of said hydraulic system is
increased compared to the volume output of a system using a
monograde hydraulic fluid having a VI of about 100, operating at
the same pressure and temperature with identical mechanical power
input from the engine or electric motor.
[0017] In another embodiment, the present invention provides a
hydraulic fluid, having a VI of at least 130.
[0018] In yet another embodiment, the present invention provides
that the above hydraulic fluid improves a power output of a
hydraulic system compared to the power output of a hydraulic system
using a monograde hydraulic fluid having a VI of about 100,
operating at the same pressure and temperature with identical
mechanical power input from the engine or electric motor.
[0019] Further, the present invention provides a hydraulic system,
comprising:
[0020] the above hydraulic fluid,
[0021] wherein said hydraulic system is a military hydraulic
system, a hydraulic launch assist system for hydraulic hybrid
vehicle propulsion, an industrial hydraulic system, marine
hydraulic system, mining hydraulic system, mobile equipment
hydraulic system or combinations thereof.
[0022] Further, the present invention provides a hydraulic system,
comprising:
[0023] the above hydraulic fluid,
[0024] wherein said hydraulic system comprises at least one unit
providing mechanical energy, at least one unit that converts
mechanical energy into hydraulic power, at least one pipe for
transmitting hydraulic fluid under pressure and at least a unit
that converts the hydraulic power of the hydraulic fluid into
mechanical work.
BRIEF DESCRIPTION OF DRAWINGS
[0025] FIG. 1 shows a comparison of power output at 5000 psi in a
piston pump (data from Table 6)
[0026] FIG. 2 shows a comparison of power output at 3000 psi in a
vane pump (data from Table 7)
DETAILED DESCRIPTION OF THE INVENTION
[0027] Especially, the improvement of hydraulic power output is
achieved by the use of a fluid according to the present
invention.
[0028] The use of a fluid having a VI of at least 130 provides an
unexpected increase in the hydraulic power output of a pump. The
increased power output from the pump results in increased power
output from the hydraulic motor (cylinder or rotary motor).
[0029] The hydraulic fluid of the present invention shows an
improved low temperature performance and broader temperature
operating window. Furthermore, the hydraulic fluid provides an
improvement in volume output. Additionally, a hydraulic system
using a hydraulic fluid having a VI of at least 130 shows an
improvement of the power drop, especially at a high load of the
unit providing mechanical work. Therefore, the constancy of the
power output is improved by the use of the present invention.
[0030] The hydraulic fluid of the present invention can be sold on
a cost favorable basis with fast investment payback time.
[0031] It is also possible to design a hydraulic system utilizing a
high viscosity index hydraulic fluid that operates at a lower
pressure level, and generates an equivalent amount of hydraulic
power output with lower pump input energy. A system that operates
at lower pressure will have longer component life (seals, hoses,
wear surfaces, fluid), and will result in lower fluid operating
temperature.
[0032] The hydraulic fluid of the present invention exhibits good
resistance to oxidation and is chemically very stable, compared to
a standard HM fluid. Specifically, the monograde hydraulic fluid of
the present invention is a HM fluid that exhibits good resistance
to oxidation and is chemically very stable, compared to a standard
HM fluid. In the context of the present invention, "HM" is a
designation for monograde hydraulic fluid based on mineral oil,
containing rust and oxidation inhibitors with antiwear
characteristics. "HV" is a designation for an HM fluid with
improved viscosity/temperature properties, intended for operation
over a wide range of ambient temperatures. Both designations are
defined by the ASTM D 6158 specification.
[0033] The viscosity of the hydraulic fluid of the present
invention can be adjusted over a broad range.
[0034] Furthermore, the hydraulic fluids of the present invention
are appropriate for high pressure applications, in the range of 100
to 700 bars. The hydraulic fluids of the present invention show a
minimal change in viscosity in-service due to good shear
stability.
[0035] Additionally, the improvement of power output and system
productivity can be achieved without constructional changes of the
hydraulic system. Consequently, the power output of both new and
old hydraulic systems can be improved at very low cost. The
composition of such hydraulic fluids are fully compatible with
existing elastomeric materials used in seals, bladders, and hoses
making them immediately acceptable for use in existing industrial
hydraulic systems.
[0036] The hydraulic fluid used according to the present invention
has a viscosity index of at least 130, preferably at least 150,
more preferably at least 180 and most preferably at least 200.
According to a preferred embodiment of the present invention, the
viscosity index is in the range of 150 to 400, more preferably 200
to 300. The viscosity index (VI) can be determined according to
ASTM D 2270. Viscosity index (VI) as defined by ASTM D2270 is the
relationship between the kinematic viscosity at 40.degree. C. and
the kinematic viscosity at 100.degree. C.
[0037] The use according to the present invention provides an
improvement of the power output of a hydraulic system. The
expression "power output" means energy usable as work, typically
measured and quantified as output torque from a rotary hydraulic
motor in horsepower or kilowatts.
[0038] Preferably, the fluid of the present invention is effective
in increasing the power output of the hydraulic system by at least
3%, more preferably at least 5% and more preferably at least 10%,
compared to the power output of a system using a monograde
hydraulic fluid having a VI of about 100 operating at the same
pressure and temperature with identical mechanical power input from
the engine or electric motor. Therefore, equal amounts of energy
are consumed (fuel or electricity), however, the system using the
high VI fluid will produce more usable output power in an equal
period of time.
[0039] According to a preferred embodiment of the present
invention, the volume output is increased. Preferably, the fluid of
the present invention is effective in increasing the volume output
of the hydraulic system by at least 3%, more preferably at least 5%
and more preferably at least 10%, compared to the volume output of
a system using a monograde hydraulic fluid having a VI of about 100
operating at the same pressure and temperature with identical
mechanical power input from the engine or electric motor. The
expression "volume output" means volume provided to a hydraulic
motor usable as work at a specific pressure difference, typically
measured and quantified in m.sup.3 or liter.
[0040] The present invention could additionally provide a method
for improving the constancy of the power output. Surprisingly, the
constancy of the power output can also be increased at the maximum
load. For example, the drop of the power output after at least 10
minutes of operating time is preferably at most 3%, measured at a
load of 90% of the maximum load or more of a unit providing
mechanical energy.
[0041] Preferably, the engine speed of a unit providing mechanical
energy is in the range of 1000 to 3000 rpm, more preferably in the
range of 1400 to 2000 rpm.
[0042] The improvements mentioned above can be used to increase the
performance of a hydraulic system in an astonishing manner. By
providing a system having a low and postponed drop of the power
output, the system can be used at the power limits of the unit
creating mechanical energy. Therefore, a defined work can be done
within a shorter time without the need of constructional changes of
the system. Preferably, the engine speed of a unit providing
mechanical energy is maintained at a constant rate and the system
delivers an increased level of hydraulic power.
[0043] According to a preferred embodiment of the present
invention, the hydraulic system can be designed to operate at a
lower pressure, such that the output power is equivalent to that
delivered by a reference system using a hydraulic fluid with a VI
of 100. E.g., in an excavator the shovel can be changed. By using a
lower pressure, the lifetime and the service intervals of the
hydraulic system can be improved in an astonishing manner.
[0044] According to a preferred embodiment of the present
invention, the hydraulic system can demonstrate an improvement in
the ratio of hydraulic power output to power input, such that the
ratio of power output/power input is preferably improved by at
least 3%, more preferably at least 5% compared to that delivered by
a reference system using a hydraulic fluid with a VI of 100.
[0045] In a preferred embodiment, the hydraulic fluid according to
the present invention increases a constancy of the power output,
preferably increases a constancy of the power output at the maximum
load. Preferably, the drop of the power output after at least 10
minutes of operating time is at most 3%, measured at a load of 90%
of the maximum load or more of a unit providing mechanical energy.
In the hydraulic system according to the present invention using
the hydraulic fluid, the engine speed of a unit providing
mechanical energy is maintained at a constant rate and the system
delivers an increased level of hydraulic power. Preferably, the
engine speed of a unit providing mechanical energy is in the range
of 1000 to 3000 rpm. More preferably, the engine speed of a unit
providing mechanical energy is in the range of 1400 to 2000 rpm.
The pressure provided by a unit providing hydraulic power is in the
range of 50 to 700 bar, preferably, in the range of 150 to 350 bar.
Preferably, the hydraulic system is designed to operate at a lower
pressure, such that the output power is equivalent to that
delivered by a reference system using a hydraulic fluid with a VI
of 100. Preferably, the hydraulic system demonstrates an
improvement in the ratio of hydraulic power output to power input,
such that the ratio of power output/power input is improved by at
least 3%, compared to that delivered by a reference system using a
hydraulic fluid with a VI of 100.
[0046] The hydraulic fluid according to the present invention may
be obtained by mixing a base fluid and a polymeric viscosity index
improver. The hydraulic fluid comprises at least 60% by weight of
at least one base fluid. Preferably, the hydraulic fluid comprises
at least 60% by weight of at least one base hydraulic fluid having
a viscosity index of 120 or less. Further, the hydraulic fluid may
comprise a member selected from the group consisting of a mineral
oil, a synthetic oil and mixtures thereof.
[0047] The hydraulic fluid may comprises an API group I oil, API
group II oil, API group III oil, a API group IV oil, API group V
oil, a Fischer-Tropsch (GTL) derived oil or mixtures thereof. In
addition, the hydraulic fluid may comprises a polyalphaolefin, a
carboxylic ester, a vegetable ester, a phosphate ester, a
polyalkylene glycol or mixtures thereof.
[0048] In another embodiment, the hydraulic fluid may comprises at
least one polymer. The polymer comprises polymerized units from
monomers selected from the group consisting of acrylate monomers,
methacrylate monomers, fumarate monomers, maleate monomers and
mixtures thereof. Preferably, the hydraulic fluid comprises a
polyalkylmethacrylate polymer.
[0049] In a preferred embodiment, the polymer is obtained by
polymerizing a mixture of olefinically unsaturated monomers, which
comprises
[0050] a) 0-100 wt % of one or more ethylenically unsaturated ester
compounds of formula (I) based on the total weight of the
ethylenically unsaturated monomers:
##STR00001##
[0051] wherein
[0052] R is hydrogen or methyl,
[0053] R.sup.1 is a linear or branched alkyl residue with 1-6
carbon atoms, R.sup.2 and R.sup.3 each independently represent
hydrogen or a group of the formula --COOR', wherein R' is hydrogen
or an alkyl group with 1-6 carbon atoms,
[0054] b) 0-100 wt % of one or more ethylenically unsaturated ester
compounds of formula (II) based on the total weight of the
ethylenically unsaturated monomers:
##STR00002##
[0055] wherein
[0056] R is hydrogen or methyl,
[0057] R.sup.4 is a linear or branched alkyl residue with 7-40
carbon atoms,
[0058] R.sup.5 and R.sup.6 independently are hydrogen or a group of
the formula --COOR'', wherein R'' is hydrogen or an alkyl group
with 7-40 carbon atoms,
[0059] c) 0-50 wt % of comonomers based on the total weight of the
ethylenically unsaturated monomers.
[0060] The polymer may be obtained by a polymerization in a API
group II mineral oil or API group III mineral oil. In addition, the
polymer may be obtained by a polymerization in a polyalphaolefin.
In another embodiment, the polymer may be obtained by polymerizing
a dispersant monomer. The polymer may be obtained by polymerizing a
vinyl monomer containing an aromatic group.
[0061] Preferably, the polymer has a weight average molecular
weight in the range of 10000 to 200000 g/mol.
[0062] The hydraulic fluid may comprises 0.5 to 40% by weight of a
polymer, preferably, 3 to 20% by weight of a polymer.
[0063] The hydraulic fluid may comprises at least two polymers
having a different monomer composition. At least one of the
polymers may a polyolefin. In another embodiment, at least one of
the polymers comprises units derived from at least one alkyl ester
monomer.
[0064] A weight ratio of the polyolefin and the polymer comprising
units derived from at least one alkyl ester monomer is in the range
of 1:10 to 10:1.
[0065] Preferably, the hydraulic fluid may comprise an oxygen
containing compound selected from the group consisting of
carboxylic acid esters, polyether polyols, organophosphorus
compounds and mixtures thereof.
[0066] The oxygen containing compound is preferably a carboxylic
ester containing at least two ester groups. The oxygen containing
compound may be a diester of a carboxylic acid containing 4 to 12
carbon atoms. Preferably, the oxygen containing compound is an
ester of a polyol. The ISO viscosity grade of the hydraulic fluid
may be in the range of 15 to 150.
[0067] The hydraulic fluid may be used at a temperature in the
range of -40.degree. C. to 120.degree. C.
[0068] Preferably, the hydraulic fluid comprises a member selected
from the group consisting of antioxidants, antiwear agents,
corrosion inhibitors, defoamers and mixtures thereof.
[0069] The viscosity of the hydraulic fluid of the present
invention can be adapted with in wide range, according to the
requirements of the hydraulic pump/motor manufacturer. ISO VG 15,
22, 32, 46, 68, 100, 150 fluid grades can be achieved, e.g.
TABLE-US-00001 ISO 3448 Maximum Viscosity Typical Viscosity,
Minimum Viscosity, Viscosity, cSt @ Grades cSt @ 40.degree. C. cSt
@ 40.degree. C. 40.degree. C. ISO VG 15 15.0 13.5 16.5 ISO VG 22
22.0 19.8 24.2 ISO VG 32 32.0 28.8 35.2 ISO VG 46 46.0 41.4 50.6
ISO VG 68 68.0 61.2 74.8 ISO VG 100 100.0 90.0 110.0 ISO VG 150
150.0 135.0 165.0
[0070] Preferably the kinematic viscosity at 40.degree. C.
according to ASTM D 445 of is the range of 15 mm.sup.2/s to 150
mm.sup.2/s, preferably 28 mm.sup.2/s to 110 mm.sup.2/s. The
kinematic viscosity at 40.degree. C. includes all values and
subvalues therebetween, especially including 20, 30, 40, 50, 60,
70, 80, 90, 100, 110, 120, 130 and 140 mm.sup.2/s.
[0071] For the use according to the present invention, preferred
hydraulic fluids are NFPA (National Fluid Power Association)
multigrade fluids, e.g. double, triple, quadra and/or penta grade
fluids as defined by NFPA T2.13.13-2002.
[0072] Preferred fluids comprise at least a mineral oil and/or a
synthetic oil.
[0073] Mineral oils are substantially known and commercially
available. They are in general obtained from petroleum or crude oil
by distillation and/or refining and optionally additional
purification and processing methods, especially the higher-boiling
fractions of crude oil or petroleum fall under the concept of
mineral oil. In general, the boiling point of the mineral oil is
higher than 200.degree. C., preferably higher than 300.degree. C.,
at 5000 Pa. Preparation by low temperature distillation of shale
oil, coking of hard coal, distillation of lignite under exclusion
of air as well as hydrogenation of hard coal or lignite is likewise
possible. To a small extent mineral oils are also produced from raw
materials of plant origin (for example jojoba, rapeseed (canola),
sunflower, and soybean oil) or animal origin (for example tallow or
neat foot oil). Accordingly, mineral oils exhibit different amounts
of aromatic, cyclic, branched and linear hydrocarbons, in each case
according to origin.
[0074] In general, one distinguishes paraffin-base, naphthenic and
aromatic fractions in crude oil or mineral oil, where the term
paraffin-base fraction stands for longer-chain or highly branched
isoalkanes and naphthenic fraction stands for cycloalkanes.
Moreover, mineral oils, in each case according to origin and
processing, exhibit different fractions of n-alkanes, isoalkanes
with a low degree of branching, so called monomethyl-branched
paraffins, and compounds with heteroatoms, especially O, N and/or
S, to which polar properties are attributed. However, attribution
is difficult, since individual alkane molecules can have both
long-chain branched and cycloalkane residues and aromatic
components. For purposes of this present invention, classification
can be done in accordance with DIN 51 378. Polar components can
also be determined in accordance with ASTM D 2007.
[0075] The fraction of n-alkanes in the preferred mineral oils is
less than 3 wt %, and the fraction of O, N and/or S-containing
compounds is less than 6 wt %. The fraction of aromatic compounds
and monomethyl-branched paraffins is in general in each case in the
range of 0-40 wt %. In accordance with one interesting aspect,
mineral oil comprises mainly naphthenic and paraffin-base alkanes,
which in general have more than 13, preferably more than 18 and
especially preferably more than 20 carbon atoms. The fraction of
these compounds is in general at least 60 wt %, preferably at least
80 wt %, without any limitation intended by this. A preferred
mineral oil contains 0.5-30 wt % aromatic components, 15-40 wt %
naphthenic components, 35-80 wt % paraffin-base components, up to 3
wt % n-alkanes and 0.05-5 wt % polar components, in each case with
respect to the total weight of the mineral oil.
[0076] An analysis of especially preferred mineral oils, which was
done with traditional methods such as urea dewaxing and liquid
chromatography on silica gel, shows, for example, the following
components, where the percentages refer to the total weight of the
relevant mineral oil:
[0077] n-alkanes with about 18-31 C atoms: 0.7-1.0%,
[0078] low-branched alkanes with 18-31 C atoms: 1.0-8.0%,
[0079] aromatic compounds with 14-32 C atoms: 0.4-10.7%,
[0080] iso- and cycloalkanes with 20-32 C atoms: 60.7-82.4%,
[0081] polar compounds: 0.1-0.8%,
[0082] loss: 6.9-19.4%.
[0083] Valuable advice regarding the analysis of mineral oil as
well as a list of mineral oils that have other compositions can be
found, for example, in Ullmann's Encyclopedia of Industrial
Chemistry, 5th Edition on CDROM, 1997, under the entry "lubricants
and related products."
[0084] Preferably, the hydraulic fluid is based on mineral oil from
API Group I, II, or III. According to a preferred embodiment of the
present invention, a mineral oil containing at least 90% by weight
saturates and at most about 0.03% sulfur measured by elemental
analysis is used. Especially, API Group II oils are preferred.
[0085] API Group IV and V synthetic oils are, among other
substances, organic esters like carboxylic esters and phosphate
esters; organic ethers like silicone oils and polyalkylene glycol;
and synthetic hydrocarbons, especially polyolefins and
Fischer-Tropsch (GTL) derived base oils. They are for the most part
somewhat more expensive than the mineral oils, but they have
advantages with regard to performance. For an explanation reference
is made to the 5 API classes of base oil types (API: American
Petroleum Institute).
TABLE-US-00002 American Petroleum Institute (API) Base Oil
Classifications Sulfur Saturates Base stock Group Viscosity Index
(weight %) (weight %) Group I 80-120 >0.03 <90 Group II
80-120 <0.03 >90 Group III >120 <0.03 >90 Group IV
all synthetic >120 <0.03 >99 Polyalphaolefins (PAO) Group
V all not >120 <0.03 included in Groups I-IV, e.g. esters,
polyalkylene glycols
[0086] The Fischer-Tropsch derived base oil may be any
Fischer-Tropsch derived base oil as disclosed in for example
EP-A-776959, EP-A-668342, WO-A-9721788, WO-0015736 WO-0014188,
WO-0014187, WO-0014183, WO-0014179, WO-0008115, WO-9941332,
EP-1029029, WO-0118156 and WO-0157166. A thorough discussion of GTL
technology can be found in: Henderson, H. E., "Gas to Liquids",
Chapter 19 of Synthetics, Mineral Oils, and Bio-Based
Lubricants--Chemistry and Technology. Rudnick, L. R., (editor), CRC
Press, Taylor and Francis, 2006, p. 317.
[0087] Synthetic hydrocarbons, include especially polyolefins.
Especially polyalphaolefins (PAO) are preferred. These compounds
are obtainable by polymerization of alkenes, especially alkenes
having 3 to 12 carbon atoms, like propene, hexene-1, octene-1, and
dodecene-1. Preferred PAOs have a number average molecular weight
in the range of 200 to 10000 g/mol, more preferably 500 to 5000
g/mol.
[0088] According to a preferred aspect of the present invention,
the hydraulic fluid may comprise an oxygen containing compound
selected from the group of carboxylic acid esters, polyether
polyols and/or organophosphorus compounds. Preferably, the oxygen
containing compound is a carboxylic ester containing at least two
ester groups, a diester of carboxylic acids containing 4 to 12
carbon atoms and/or a ester of a polyol. By using an oxygen
containing compound as a basestock, the fire resistance of the
hydraulic fluid can be improved.
[0089] Phosphorus ester fluids can be used as a component of the
hydraulic fluid such as alkyl aryl phosphate ester; trialkyl
phosphates such as tributyl phosphate or tri-2-ethylhexyl
phosphate; triaryl phosphates such as mixed isopropylphenyl
phosphates, mixed t-butylphenyl phosphates, trixylenyl phosphate,
or tricresylphosphate. Additional classes of organophosphorus
compounds are phosphonates and phosphinates, which may contain
alkyl and/or aryl substituents. Dialkyl phosphonates such as
di-2-ethylhexylphosphonate; alkyl phosphinates such as
di-2-ethylhexylphosphinate are useful. As the alkyl group herein,
linear or branched chain alkyls comprising 1 to 10 carbon atoms are
preferred. As the aryl group herein, aryls comprising 6 to 10
carbon atoms that maybe substituted by alkyls are preferred.
Especially, the hydraulic fluids may contain 0 to 60% by weight,
preferably 5 to 50% by weight organophosphorus compounds. The
amount of organophosphorous compounds includes all values and
subvalues therebetween, especially including 5, 10, 15, 20, 25, 30,
35, 40, 45, 50, 55% by weight.
[0090] As the carboxylic acid esters reaction products of alcohols
such as polyhydric alcohol, monohydric alcohol and the like, and
fatty acids such as mono carboxylic acid, polycarboxylic acid and
the like can be used. Such carboxylic acid esters can of course be
a partial ester.
[0091] Carboxylic acid esters may have one carboxylic ester group
having the formula R--COO--R, wherein R is independently a group
comprising 1 to 40 carbon atoms. Preferred ester compounds comprise
at least two ester groups. These compounds may be based on
polycarboxylic acids having at least two acidic groups and/or
polyols having at least two hydroxyl groups.
[0092] The polycarboxylic acid residue usually has 2 to 40,
preferably 4 to 24, especially 4 to 12 carbon atoms. Useful
polycarboxylic acids esters are, e.g., esters of adipic, azelaic,
sebacic, phthalate and/or dodecanoic acids. The alcohol component
of the polycarboxylic acid compound preferably comprises 1 to 20,
especially 2 to 10 carbon atoms.
[0093] Examples of useful alcohols are methanol, ethanol, propanol,
butanol, pentanol, hexanol, heptanol and octanol. Furthermore,
oxoalcohols can be used such as diethylene glycol, triethylene
glycol, tetraethylene glycol up to decamethylene glycol.
[0094] Especially preferred compounds are esters of polycarboxylic
acids with alcohols comprising one hydroxyl group. Examples of
these compounds are described in Ullmanns Encyclopadie der
Technischen Chemie, third edition, vol. 15, page 287-292, Urban
& Schwarzenber (1964)).
[0095] Useful polyols to obtain ester compounds comprising at least
two ester groups contain usually 2 to 40, preferably 4 to 22 carbon
atoms. Examples are neopentyl glycol, diethylene glycol,
dipropylene glycol,
2,2-dimethyl-3-hydroxypropyl-2',2'-dimethyl-3'-hydroxy propionate,
glycerol, trimethylolethane, trimethanol propane,
trimethylolnonane, ditrimethylol-propane, pentaerythritol,
sorbitol, mannitol and dipentaerythritol. The carboxylic acid
component of the polyester may contain 1 to 40, preferably 2 to 24
carbon atoms. Examples are linear or branched saturated fatty acids
such as formic acid, acetic acid, propionic acid, octanoic acid,
caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric
acid, undecanoic acid, lauric acid, tridecanoic acid, myrisric
acid, pentadecanoic acid, palmitic acid, heptadecanoic acid,
stearic acid, nonadecanoic acid, arachic acid, behenic acid,
iso-myiristic acid, isopalmitic acid, isostearic acid,
2,2-dimethylbutanoic acid, 2,2-dimethylpentanoic acid,
2,2-dimethyloctanoic acid, 2-ethyl-2,3,3-trimethylbutanoic acid,
2,2,3,4-tetramethylpentanoic acid,
2,5,5-trimethyl-2-t-butylhexanoic acid,
2,3,3-trimethyl-2-ethylbutanoic acid,
2,3-dimethyl-2-isopropylbutanoic acid, 2-ethylhexanoic acid,
3,5,5-trimethylhexanoic, acid; linear or branched unsaturated fatty
such as linoleic acid, linolenic acid, 9 octadecenoic acid,
undecenoic acid, elaidic acid, cetoleic acid, erucic acid,
brassidic acid, and commercial grades of oleic acid from a variety
of animal fat or vegetable oil sources. Mixtures of fatty acids
such as tall oil fatty acids can be used.
[0096] Especially useful compounds comprising at least two ester
groups are, e.g., neopentyl glycol tallate, neopentyl glycol
dioleate, propylene glycol tallate, propylene glycol dioleate,
diethylene glycol tallate, and diethylene glycol dioleate.
[0097] Many of these compounds are commercially available from
Inolex Chemical Co. under the trademark Lexolube 2G-214, from
Cognis Corp. under the trademark ProEco 2965, from Uniqema Corp.
under the trademarks Priolube 1430 and Priolube 1446 and from
Georgia Pacific under the trademarks Xtolube 1301 and Xtolube
1320.
[0098] Furthermore, ethers are useful as a component of the
hydraulic fluid. Preferably, polyether polyols are used as a
component of the hydraulic fluid of the present invention. Examples
are polyalkylene glycols like, e.g., polyethylene glycols,
polypropylene glycols and polybutylene glycols. The polyalkylene
glycols can be based on mixtures of alkylene oxides. These
compounds preferably comprise 1 to 40 alkylene oxide units, more
preferably 5 to 30 alkylene oxide units. Polybutylene glycols are
preferred compounds for anhydrous fluids. The polyether polyols may
comprise further groups, like e.g., alkylene or arylene groups
comprising 1 to 40, especially 2 to 22 carbon atoms.
[0099] According to another aspect of the present invention, the
hydraulic fluid is based on a synthetic basestock comprising
polyalphaolefin (PAO), carboxylic esters (diester, or polyol
ester), a vegetable ester, phosphate ester (trialkyl, triaryl, or
alkyl aryl phosphates), and/or polyalkylene glycol (PAG). Preferred
synthetic basestocks are API Group IV and/or Group V oils.
[0100] Preferably, the hydraulic fluid is obtainable by mixing at
least two components. At least one of the components shall be a
base oil. The expression base oil includes mineral oil and/or
synthetic oil on which the hydraulic fluid could be based as
mentioned above. Preferably, the hydraulic fluid comprises at least
60% by weight of base oil. Preferably, at least one of the
components may have a viscosity index of 120 or less. According to
a preferred embodiment, the hydraulic fluid may comprise at least
60% by weight of at least one component having a viscosity index of
120 or less.
[0101] Particularly, a polymeric viscosity index improver can be
used as a component of the hydraulic fluid. Viscosity index
improvers are e.g. disclosed in Ullmann's Encyclopedia of
Industrial Chemistry, 5th Edition on CD-ROM, 1997.
[0102] Preferred polymers useful as VI improvers comprise units
derived from alkyl esters having at least one ethylenically
unsaturated group. Preferred polymers are obtainable by
polymerizing, in particular, (meth)acrylates, maleates and
fumarates. The term (meth)acrylates includes methacrylates and
acrylates as well as mixtures of the two. The alkyl residue can be
linear, cyclic or branched.
[0103] Mixtures to obtain preferred polymers comprising units
derived from alkyl esters contain 0 to 100 wt %, preferably 0.5 to
90 wt %, especially 1 to 80 wt %, more preferably 1 to 30 wt %,
more preferably 2 to 20 wt %, based on the total weight of the
monomer mixture, of one or more ethylenically unsaturated ester
compounds of formula (I)
##STR00003##
[0104] where R is hydrogen or methyl, R.sup.1 means a linear or
branched alkyl residue with 1-6, especially 1 to 5 and preferably 1
to 3 carbon atoms, R.sup.2 and R.sup.3 are independently hydrogen
or a group of the formula --COOR', where R' means hydrogen or an
alkyl group with 1-6 carbon atoms. The amount of a compound of
formula (I) in the mixture includes all values and subvalues
therebetween, especially including 5, 10, 15, 20, 25, 30, 35, 40,
45, 50, 55, 60, 65, 70, 75, 80, 85, 90 and 95% by weight.
[0105] Examples of component (a) are, among others,
(meth)acrylates, fumarates and maleates, which derived from
saturated alcohols such as methyl (meth)acrylate, ethyl
(meth)acrylate, n-propyl(meth)acrylate, isopropyl (meth)acrylate,
n-butyl (meth)acrylate, tert-butyl(meth)acrylate,
pentyl(meth)acrylate and hexyl (meth)acrylate; cycloalkyl
(meth)acrylates, like cyclopentyl(meth)acrylate.
[0106] Furthermore, the monomer compositions to obtain the polymers
comprising units derived from alkyl esters contain 0-100 wt %,
preferably 10-99 wt %, especially 20-95 wt % and more preferably 30
to 85 wt %, based on the total weight of the monomer mixture, of
one or more ethylenically unsaturated ester compounds of formula
(II)
##STR00004##
[0107] where R is hydrogen or methyl, R.sup.4 means a linear or
branched alkyl residue with 7-40, especially 10 to 30 and
preferably 12 to 24 carbon atoms, R.sup.5 and R.sup.6 are
independently hydrogen or a group of the formula --COOR'', where
R'' means hydrogen or an alkyl group with 7 to 40, especially 10 to
30 and preferably 12 to 24 carbon atoms. The amount of a compound
of formula (II) in the mixture includes all values and subvalues
therebetween, especially including 5, 10, 15, 20, 25, 30, 35, 40,
45, 50, 55, 60, 65, 70, 75, 80, 85, 90 and 95% by weight.
[0108] Among these are (meth)acrylates, fumarates and maleates that
derive from saturated alcohols, such as 2-ethylhexyl
(meth)acrylate, heptyl (meth)acrylate, 2-tert-butylheptyl
(meth)acrylate, octyl (meth)acrylate, 3-isopropylheptyl
(meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl
(meth)acrylate, 5-methylundecyl (meth)acrylate, dodecyl
(meth)acrylate, 2-methyldodecyl (meth)acrylate, tridecyl
(meth)acrylate, 5-methyltridecyl (meth)acrylate, tetradecyl
(meth)acrylate, pentadecyl (meth)acrylate, 2-methylhexadecyl
(meth)acrylate, heptadecyl (meth)acrylate, 5-isopropylheptadecyl
(meth)acrylate, 4-tert-butyloctadecyl (meth)acrylate,
5-ethyloctadecyl (meth)acrylate, 3-isopropyloctadecyl
(meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate,
eicosyl (meth)acrylate, cetyleicosyl (meth)acrylate, stearyleicosyl
(meth)acrylate, docosyl (meth)acrylate, and/or
eicosyltetratriacontyl (meth)acrylate;
[0109] cycloalkyl (meth)acrylates such as 3-vinylcyclohexyl
(meth)acrylate, cyclohexyl (meth)acrylate, bornyl (meth)acrylate,
2,4,5-tri-t-butyl-3-vinylcyclohexyl(meth)acrylate,
2,3,4,5-tetra-t-butylcyclohexyl (meth)acrylate; and the
corresponding fumarates and maleates.
[0110] The ester compounds with a long-chain alcohol residue,
especially component (b), can be obtained, for example, by reacting
(meth)acrylates, fumarates, maleates and/or the corresponding acids
with long chain fatty alcohols, where in general a mixture of
esters such as (meth)acrylates with different long chain alcohol
residues results. These fatty alcohols include, among others, Oxo
Alcohol.RTM. 7911 and Oxo Alcohol.RTM. 7900, Oxo Alcohol.RTM. 1100
(Monsanto); Alphanol.RTM. 79 (ICI); Nafol.RTM..degree.1620,
Alfol.RTM. 610 and Alfol.RTM. 810 (Sasol); Epal.RTM. 610 and
Epal.RTM. 810 (Ethyl Corporation); Linevol.RTM. 79, Linevol.RTM.
911 and Dobanol.RTM. 25L (Shell AG); Lial 125 (Sasol); Dehydad.RTM.
and Dehydad.RTM. (and Lorol.RTM. (Cognis).
[0111] Of the ethylenically unsaturated ester compounds, the
(meth)acrylates are particularly preferred over the maleates and
furmarates, i.e., R.sup.2, R.sup.3, R.sup.5, R.sup.6 of formulas
(I) and (II) represent hydrogen in particularly preferred
embodiments.
[0112] In a particular aspect of the present invention, preference
is given to using mixtures of ethylenically unsaturated ester
compounds of formula (II), and the mixtures have at least one
(meth)acrylate having from 7 to 15 carbon atoms in the alcohol
radical and at least one (meth) acrylate having from 16 to 30
carbon atoms in the alcohol radical. The fraction of the
(meth)acrylates having from 7 to 15 carbon atoms in the alcohol
radical is preferably in the range from 20 to 95% by weight, based
on the weight of the monomer composition for the preparation of
polymers. The fraction of the (meth)acrylates having from 16 to 30
carbon atoms in the alcohol radical is preferably in the range from
0.5 to 60% by weight based on the weight of the monomer composition
for the preparation of the polymers comprising units derived from
alkyl esters. The weight ratio of the (meth)acrylate having from 7
to 15 carbon atoms in the alcohol radical and the (meth) acrylate
having from 16 to 30 carbon atoms in the alcohol radical is
preferably in the range of 10:1 to 1:10, more preferably in the
range of 5:1 to 1.5:1.
[0113] Component (c) comprises in particular ethylenically
unsaturated monomers that can copolymerize with the ethylenically
unsaturated ester compounds of formula (I) and/or (II).
[0114] Comonomers that correspond to the following formula are
especially suitable for polymerization in accordance with the
present invention:
##STR00005##
[0115] where R.sup.1* and R.sup.2* independently are selected from
the group consisting of hydrogen, halogens, CN, linear or branched
alkyl groups with 1-20, preferably 1-6 and especially preferably
1-4 carbon atoms, which can be substituted with 1 to (2n+1) halogen
atoms, where n is the number of carbon atoms of the alkyl group
(for example CF3), .alpha., .beta.-unsaturated linear or branched
alkenyl or alkynyl groups with 2-10, preferably 2-6 and especially
preferably 2-4 carbon atoms, which can be substituted with 1 to
(2n-1) halogen atoms, preferably chlorine, where n is the number of
carbon atoms of the alkyl group, for example CH2.dbd.CCl--,
cycloalkyl groups with 3-8 carbon atoms, which can be substituted
with 1 to (2n-1) halogen atoms, preferably chlorine, where n is the
number of carbon atoms of the cycloalkyl group; C(.dbd.Y*)R.sup.5*,
C(.dbd.Y*)NR.sup.6*R.sup.7*, Y*C(.dbd.Y*)R.sup.5*, SOR.sup.5*,
SO.sub.2R.sup.5*, OSO.sub.2R.sup.5*, NR.sup.8*SO.sub.2R.sup.5*,
PR.sup.5*.sub.2, P(.dbd.Y*)R.sup.5*.sub.2, Y*PR.sup.5*.sub.2,
Y*P(.dbd.Y*)R.sup.5*.sub.2, NR.sup.8*.sub.2, which can be
quaternized with an additional R.sup.8*, aryl, or heterocyclyl
group, where Y* can be NR.sup.8*, S or O, preferably O; R.sup.5* is
an alkyl group with 1-20 carbon atoms, an alkylthio group with 1-20
carbon atoms, OR.sup.1 (R.sup.15 is hydrogen or an alkali metal),
alkoxy with 1-20 carbon atoms, aryloxy or heterocyclyloxy; R.sup.6*
and R.sup.7* independently are hydrogen or an alkyl group with one
to 20 carbon atoms, or R.sup.6* and R.sup.7* together can form an
alkylene group with 2-7, preferably 2-5 carbon atoms, where they
form a 3-8 member, preferably 3-6 member ring, and R.sup.8* is
linear or branched alkyl or aryl groups with 1-20 carbon atoms;
[0116] R.sup.3* and R.sup.4* independently are chosen from the
group consisting of hydrogen, halogen (preferably fluorine or
chlorine), alkyl groups with 1-6 carbon atoms and COOR.sup.9*,
where R.sup.9* is hydrogen, an alkali metal or an alkyl group with
1-40 carbon atoms, or R.sup.1* and R.sup.3* can together form a
group of the formula (CH.sub.2).sub.n, which can be substituted
with 1-2n' halogen atoms or C.sub.1-C.sub.4 alkyl groups, or can
form a group of the formula C(.dbd.O)--Y*--C(.dbd.O), where n' is
from 2-6, preferably 3 or 4, and Y* is defined as before; and where
at least 2 of the residues R.sup.1*, R.sup.2*, R.sup.3* and
R.sup.4* are hydrogen or halogen.
[0117] The comonomers include, among others,
hydroxyalkyl(meth)acrylates like 3-hydroxypropyl(meth)acrylate,
3,4-dihydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate,
2-hydroxypropyl (meth)acrylate, 2,5-dimethyl-1,6-hexanediol
(meth)acrylate, 1,10-decanediol (meth)acrylate;
[0118] aminoalkyl (meth)acrylates and aminoalkyl (meth)acrylamides
like N-(3-dimethylaminopropyl)methacrylamide, 3-diethylaminopentyl
(meth)acrylate, 3-dibutylaminohexadecyl (meth)acrylate;
[0119] nitriles of (meth)acrylic acid and other nitrogen-containing
(meth)acrylates like N-(methacryloyloxyethyl)diisobutylketimine,
N-(methacryloyloxyethyl)dihexadecylketimine,
(meth)acryloylamidoacetonitrile,
2-methacryloyloxyethylmethylcyanamide, cyanomethyl
(meth)acrylate;
[0120] aryl (meth)acrylates like benzyl (meth)acrylate or phenyl
(meth)acrylate, where the acryl residue in each case can be
unsubstituted or substituted up to four times;
[0121] carbonyl-containing (meth)acrylates like 2-carboxyethyl
(meth)acrylate, carboxymethyl (meth)acrylate, oxazolidinylethyl
(meth)acrylate,
[0122] N-methyacryloyloxy)formamide, acetonyl (meth)acrylate,
N-methacryloylmorpholine, N-methacryloyl-2-pyrrolidinone,
N-(2-methyacryloxyoxyethyl)-2-pyrrolidinone,
N-(3-methacryloyloxypropyl)-2-pyrrolidinone,
N-(2-methyacryloyloxypentadecyl(-2-pyrrolidinone,
N-(3-methacryloyloxyheptadecyl-2-pyrrolidinone;
[0123] (meth)acrylates of ether alcohols like tetrahydrofurfuryl
(meth)acrylate, vinyloxyethoxyethyl (meth)acrylate,
methoxyethoxyethyl (meth)acrylate, 1-butoxypropyl (meth)acrylate,
1-methyl-(2-vinyloxy)ethyl (meth)acrylate, cyclohexyloxymethyl
(meth)acrylate, methoxymethoxyethyl (meth)acrylate, benzyloxyl
methyl (meth)acrylate, furfuryl (meth)acrylate, 2-butoxyethyl
(meth)acrylate, 2-ethoxyethoxymethyl (meth)acrylate, 2-ethoxyethyl
(meth)acrylate, ethoxylated (meth)acrylates, allyloxymethyl
(meth)acrylate, 1-ethoxybutyl (meth)acrylate, methoxymethyl
(meth)acrylate, 1-ethoxyethyl (meth)acrylate, ethoxymethyl
(meth)acrylate;
[0124] (meth)acrylates of halogenated alcohols like
2,3-dibromopropyl (meth)acrylate, 4-bromophenyl (meth)acrylate,
1,3-dichloro-2-propyl (meth)acrylate, 2-bromoethyl (meth)acrylate,
2-iodoethyl(meth)acrylate, chloromethyl(meth)acrylate;
[0125] oxiranyl (meth)acrylate like 2,3-epoxybutyl (meth)acrylate,
3,4-epoxybutyl (meth)acrylate, 10,11 epoxyundecyl (meth)acrylate,
2,3-epoxycyclohexyl (meth)acrylate, oxiranyl (meth)acrylates such
as 10,11-epoxyhexadecyl(meth)acrylate, glycidyl (meth)acrylate;
[0126] phosphorus-, boron- and/or silicon-containing
(meth)acrylates like 2-(dimethylphosphato)propyl (meth)acrylate,
2-(ethylphosphito) propyl (meth)acrylate, 2-dimethylphosphinomethyl
(meth)acrylate, dimethylphosphonoethyl (meth)acrylate,
diethylmethacryloyl phosphonate, dipropylmethacryloyl phosphate, 2
(dibutylphosphono)ethyl(meth)acrylate,
2,3-butylenemethacryloylethyl borate,
methyldiethoxymethacryloylethoxysiliane, diethylphosphatoethyl
(meth)acrylate;
[0127] sulfur-containing (meth)acrylates like
ethylsulfinylethyl(meth)acrylate, 4-thiocyanatobutyl(meth)acrylate,
ethylsulfonylethyl(meth)acrylate, thiocyanatomethyl (meth)acrylate,
methylsulfinylmethyl (meth)acrylate, bis(methacryloyloxyethyl)
sulfide;
[0128] heterocyclic (meth)acrylates like
2-(1-imidazolyl)ethyl(meth)acrylate,
2-(4-morpholinyl)ethyl(meth)acrylate and
1-(2-methacryloyloxyethyl)-2-pyrrolidone;
[0129] vinyl halides such as, for example, vinyl chloride, vinyl
fluoride, vinylidene chloride and vinylidene fluoride;
[0130] vinyl esters like vinyl acetate;
[0131] vinyl monomers containing aromatic groups like styrene,
substituted styrenes with an alkyl substituent in the side chain,
such as .alpha.-methylstyrene and .alpha.-ethylstyrene, substituted
styrenes with an alkyl substituent on the ring such as vinyltoluene
and .alpha.-methylstyrene, halogenated styrenes such as
monochlorostyrenes, dichlorostyrenes, tribromostyrenes and
tetrabromostyrenes;
[0132] heterocyclic vinyl compounds like 2-vinylpyridine,
3-vinylpyridine, 2-methyl-5-vinylpyridine, 3-ethyl-4-vinylpyridine,
2,3-dimethyl-5-vinylpyridine, vinylpyrimidine, vinylpiperidine,
9-vinylcarbazole, 3-vinylcarbazole, 4-vinylcarbazole,
1-vinylimidazole, 2-methyl-1-vinylimidazole, N-vinylpyrrolidone,
2-vinylpyrrolidone, N-vinylpyrrolidine, 3-vinylpyrrolidine,
N-vinylcaprolactam, N-vinylbutyrolactam, vinyloxolane, vinylfuran,
vinylthiophene, vinylthiolane, vinylthiazoles and hydrogenated
vinylthiazoles, vinyloxazoles and hydrogenated vinyloxazoles;
[0133] vinyl and isoprenyl ethers;
[0134] maleic acid derivatives such as maleic anhydride,
methylmaleic anhydride, maleinimide, methylmaleinimide;
[0135] fumaric acid and fumaric acid derivatives such as, for
example, mono- and diesters of fumaric acid.
[0136] Monomers that have dispersing functionality can also be used
as comonomers. These monomers contain usually hetero atoms such as
oxygen and/or nitrogen. For example the previously mentioned
hydroxyalkyl(meth)acrylates, aminoalkyl (meth)acrylates and
aminoalkyl (meth)acrylamides, (meth)acrylates of ether alcohols,
heterocyclic (meth)acrylates and heterocyclic vinyl compounds are
considered as dispersing comononers.
[0137] Especially preferred mixtures contain methyl methacrylate,
lauryl methacrylate and/or stearyl methacrylate.
[0138] The components can be used individually or as mixtures.
[0139] The hydraulic fluid of the present invention preferably
comprises polyalkylmethacrylate polymers. These polymers are
obtainable by polymerizing compositions comprising
alkyl-methacrylate monomers. Preferably, these
polyalkylmethacrylate polymers comprise at least 40% by weight,
especially at least 50% by weight, more preferably at least 60% by
weight and most preferably at least 80% by weight methacrylate
repeating units. Preferably, these polyalkylmethacrylate polymers
comprise C.sub.9-C.sub.24 methacrylate repeating units and
C.sub.1-C.sub.8 methacrylate repeating units.
[0140] The molecular weight of the polymers derived from alkyl
esters is not critical. Usually the polymers derived from alkyl
esters have a molecular weight in the range of 300 to 1,000,000
g/mol, preferably in the range of range of 10000 to 200,000 g/mol
and more preferably in the range of 25000 to 100,000 g/mol, without
any limitation intended by this. These values refer to the weight
average molecular weight of the polymers.
[0141] Without intending any limitation by this, the
alkyl(meth)acrylate polymers exhibit a polydispersity, given by the
ratio of the weight average molecular weight to the number average
molecular weight Mw/Mn, in the range of 1 to 15, preferably 1.1 to
10, especially preferably 1.2 to 5. The polydispersity may be
determined by gel permeation chromatography (GPC). The preferred
polydipersity includes all values and subvalues therebetween,
especially including 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1,
2.5, 3, 3.5, 4 and 4.5.
[0142] The monomer mixtures described above can be polymerized by
any known method. Conventional radical initiators can be used to
perform a classic radical polymerization. Examples for these
radical initiators are azo initiators like
2,2'-azodiisobutyronitrile (AIBN),
2,2'-azobis(2-methylbutyronitrile) and 1,1 azo-biscyclohexane
carbonitrile; peroxide compounds, e.g. methyl ethyl ketone
peroxide, acetyl acetone peroxide, dilauryl peroxide, tert.-butyl
per-2-ethyl hexanoate, ketone peroxide, methyl isobutyl ketone
peroxide, cyclohexanone peroxide, dibenzoyl peroxide, tert.-butyl
perbenzoate, tert.-butyl peroxy isopropyl carbonate,
2,5-bis(2-ethylhexanoyl-peroxy)-2,5-dimethyl hexane, tert.-butyl
peroxy 2-ethyl hexanoate, tert.-butyl peroxy-3,5,5-trimethyl
hexanoate, dicumene peroxide, 1,1 bis(tert. butyl
peroxy)cyclohexane, 1,1 bis(tert. butyl peroxy) 3,3,5-trimethyl
cyclohexane, cumene hydroperoxide and tert.-butyl
hydroperoxide.
[0143] Low weight average molecular weight poly(meth)acrylates can
be obtained by using chain transfer agents. This technology is
ubiquitously known and practiced in the polymer industry and is
described in Odian, Principles of Polymerization, 1991. Examples of
chain transfer agents are sulfur containing compounds such as
thiols, e.g. n- and t-dodecanethiol, 2-mercaptoethanol, and
mercapto carboxylic acid esters, e.g. methyl-3-mercaptopropionate
Preferred chain transfer agents contain up to 20, especially up to
15 and more preferably up to 12 carbon atoms. Furthermore, chain
transfer agents may contain at least 1, especially at least 2
oxygen atoms.
[0144] Furthermore, the low weight average molecular weight
poly(meth)acrylates can be obtained by using transition metal
complexes, such as low spin cobalt complexes. These technologies
are well known and for example described in USSR patent 940,487-A
and by Heuts, et al., Macro-molecules 1999, pp 2511-2519 and
3907-3912.
[0145] Furthermore, polymerization techniques such as ATRP (Atom
Transfer Radical Polymerization) and or RAFT (Reversible Addition
Fragmentation Chain Transfer) can be applied to obtain useful
polymers derived from alkyl esters. The ATRP reaction method is
described, for example, by J- S. Wang, et al., J. Am. Chem. Soc.,
Vol. 117, pp. 5614-5615 (1995), and by Matyjaszewski,
Macromolecules, Vol. 28, pp. 7901-7910 (1995). Moreover, the patent
applications WO 96/30421, WO 97/47661, WO 97/18247, WO 98/40415 and
WO 99/10387 disclose variations of the ATRP explained above to
which reference is expressly made for purposes of the disclosure.
The RAFT method is extensively presented in WO 98/01478, for
example, to which reference is expressly made for purposes of the
disclosure.
[0146] The polymerization can be carried out at normal pressure,
reduced pressure or elevated pressure. The polymerization
temperature is also not critical. However, in general it lies in
the range of -20-200.degree. C., preferably 0-130.degree. C. and
especially preferably 60-120.degree. C., without any limitation
intended by this.
[0147] The polymerization can be carried out with or without
solvents. The term solvent is to be broadly understood here.
[0148] According to a preferred embodiment, the polymer is
obtainable by a polymerization in API Group II or Group III mineral
oil. These solvents are disclosed above.
[0149] Furthermore, polymers obtainable by polymerization in a
polyalphaolefin (PAO) are preferred. More preferably, the PAO has a
number average molecular weight in the range of 200 to 10000, more
preferably 500 to 5000 g/mol. This solvent is disclosed above.
[0150] The hydraulic fluid may comprise 0.5 to 50% by weight,
especially 1 to 30% by weight, and preferably 3 to 20% by weight,
based on the total weight of the fluid, of one or more polymers
derived from alkyl esters. According to a preferred embodiment of
the present invention, the hydraulic fluid comprises at least 5% by
weight of one or more polymers derived from alkyl esters. The
amount of one or more polymers derived from alkyl esters includes
all values and subvalues therebetween, especially including 5, 10,
15, 20, 25, 30, 35, 40 and 45% by weight.
[0151] According to a preferred aspect of the present invention,
the fluid may comprise at least two polymers having a different
monomer composition. Preferably at least one of the polymers is
derived from alkyl esters. In another embodiment, at least one of
the polymers is a polyolefin. A preferred combination is the use of
a polymer derived from an alkyl ester, and a polymer derived from
polyolefins. Preferably, the polyolefin is useful as a viscosity
index improver.
[0152] These polyolefins include in particular polyolefin
copolymers (OCP) and hydrogenated styrene/diene copolymers (HSD).
The polyolefin copolymers (OCP) to be used according to the present
invention are primarily polymers synthesized from ethylene,
propylene, isoprene, butylene and/or further olefins having 5 to 20
carbon atoms. Systems which have been grafted with small amounts of
oxygen- or nitrogen-containing monomers (e.g. from 0.05 to 5% by
weight of maleic anhydride) may also be used. The copolymers which
contain diene components are generally hydrogenated in order to
reduce the oxidation sensitivity and the crosslinking tendency of
the viscosity index improvers.
[0153] The weight average molecular weight Mw is in general from 10
000 to 300 000, preferably between 50 000 and 150 000. Such olefin
copolymers are described, for example, in the German Laid-Open
Applications DE-A 16 44 941, DE-A 17 69 834, DE-A 19 39 037, DE-A
19 63 039, and DEA 20 59 981.
[0154] Ethylene/propylene copolymers are particularly useful and
terpolymers having ternary components, such as
ethylidene-norbornene (cf. Macromolecular Reviews, Vol. 10 (1975))
are also possible, but their tendency to crosslink must also be
taken into account in the aging process. The distribution may be
substantially random, but sequential polymers comprising ethylene
blocks can also advantageously be used. The ratio of the monomers
ethylene/propylene is variable within certain limits, which can be
set to about 75% for ethylene and about 80% for propylene as an
upper limit. Owing to its reduced tendency to dissolve in oil,
polypropylene is less suitable than ethylene/propylene copolymers.
In addition to polymers having a predominantly atactic propylene
incorporation, those having a more pronounced isotactic or
syndiotactic propylene incorporation may also be used.
[0155] Such products are commercially available, for example under
the trade names Dutral.RTM. CO 034, Dutral.RTM. CO 038, Dutral.RTM.
CO 043, Dutral.RTM. CO 058, Buna.RTM. EPG 2050 or Buna.RTM. EPG
5050.
[0156] The hydrogenated styrene/diene copolymers (HSD) are being
described, for example, in DE 21 56 122. They are in general
hydrogenated isoprene/styrene or butadiene/styrene copolymers. The
ratio of diene to styrene is preferably in the range from 2:1 to
1:2, particularly preferably about 55:45. The weight average
molecular weight Mw is in general from 10000 to 300 000, preferably
between 50000 and 150000 g/mol. According to a particular aspect of
the present invention, the proportion of double bonds after the
hydrogenation is not more than 15%, particularly preferably not
more than 5%, based on the number of double bonds before the
hydrogenation.
[0157] Hydrogenated styrene/diene copolymers can be commercially
obtained under the trade name SHELLVIS.RTM. 50, 150, 200, 250 or
260.
[0158] Preferably, at least one of the polymers of the mixture
comprises units derived from monomers selected from acrylate
monomers, methacrylate monomers, fumarate monomers and/or maleate
monomers. These polymers are described above.
[0159] The weight ratio of the polyolefin and the polymer comprises
units derived from monomers selected from acrylate monomers,
methacrylate monomers, fumarate monomers and/or maleate monomers
may be in the range of 1:10 to 10:1, especially 1:5 to 5:1.
[0160] The hydraulic fluid may comprise usual additives. These
additive include e.g. antioxidants, antiwear agents, corrosion
inhibitors and/or defoamers, often purchased as a commercial
additive package.
[0161] Preferably, the hydraulic fluid has a viscosity according to
ASTM D 445 at 40.degree. C. in the range of 10 to 150 mm.sup.2/s,
more preferably 22 to 100 mm.sup.2/s.
[0162] Preferably, the hydraulic system includes the following
components: [0163] 1. A unit creating mechanical energy, e.g. a
combustion engine or an electrical motor. [0164] 2. A fluid flow or
force-generating unit that converts mechanical energy into
hydraulic power, such as a pump. [0165] 3. Piping for transmitting
fluid under pressure. [0166] 4. A unit that converts the hydraulic
power of the fluid into mechanical work or motion, such as an
actuator or fluid motor. There are two types of motors, cylindrical
and rotary. [0167] 5. A control circuit with valves that regulate
flow, pressure, direction of movement, and applied forces. [0168]
6. A fluid reservoir that allows for separation of water, foam,
entrained air, or debris before the clean fluid is returned to the
system through a filter. [0169] 7. A liquid with low
compressibility capable of operating without degradation under the
conditions of the application (temperature, pressure,
radiation).
[0170] Most complex systems will make use of multiple pumps, rotary
motors, cylinders, electronically controlled with valves and
regulators.
[0171] According to a preferred embodiment of the present
invention, a vane pump or a piston pump can be used in order to
create hydraulic power.
[0172] The system may be operated at high pressures. The
improvement of the present invention can be achieved at pressures
in the range of 50 to 700 bars, preferably 100 to 400 bars and more
preferably 150 to 350 bars.
[0173] The unit creating mechanical energy, e.g. a motor can be
operated at a speed of 500 to 5000 rpm, preferably 1000 to 3000 rpm
and more preferably 1400 to 2000 rpm.
[0174] The hydraulic fluid can be used over a wide temperature
window. Preferably, the fluid can be used at a temperature in the
range of -30.degree. C. to 200.degree. C., more preferably
10.degree. C. to 150.degree. C., even more preferably 20-00.degree.
C., and most preferably 20-50.degree. C. Usually, the operating
temperature depends on the base fluid used to manufacture the
hydraulic fluid.
[0175] Preferably, the fluid is used in military hydraulic systems,
in hydraulic launch assist systems for hybrid propulsion vehicles,
in industrial, marine, mining and/or mobile equipment hydraulic
systems.
[0176] Furthermore, the present invention provides a hydraulic
system comprising a hydraulic fluid having a VI of at least 130, a
unit for creating mechanical power, a unit that converts mechanical
power into hydraulic power, and a unit that converts hydraulic
power into mechanical work or motion.
[0177] Preferentially, engine speed can be maintained at a constant
level to deliver higher amounts of hydraulic power. Preferably, the
mechanical power output of the engine or electrical motor can be
operated at its full power capacity to deliver higher amounts of
hydraulic power compared to the hydraulic system utilizing a
standard HM grade fluid with a viscosity index less than 120.
[0178] Moreover, the increase in power output from a hydraulic
system can be magnified when a pump and rotary motor are combined.
In such a system, the use of a hydraulic fluid with high viscosity
index according to the present invention will increase the volume
flow rate and power output of the pump, which then flows to one or
more rotary motors. This effect is repeated in the rotary motor and
thus multiplies the increase in total power output from the system.
As a simple example, a high viscosity index fluid is substituted
for an HM fluid to increase the power output of a pump by 5%. That
fluid then flows into a rotary motor which also experiences a 5%
increase in power output as it provides mechanical work. The total
power output of the pump and motor system is thus improved by over
10%, as described in the following simple example.
[0179] System A with HM oil-10.0 kW into the pump from the engine,
9.0 kW out of the pump into the rotary motor, 8.1 kW out of the
motor as mechanical work.
[0180] System B with HVI oil-10.0 kW into the pump from the engine,
9.45 kW out of the pump into the rotary motor, 8.93 kW out of the
motor as mechanical work.
[0181] The hydraulic pump from System B delivers 5% more power than
the pump from System A [(9.45-9.0)/9.0=0.05.times.100=5%].
[0182] The hydraulic system System B delivers 10.2% more power than
System A [(8.93-8.1)/8.1=0.102.times.100=10.2%].
[0183] Having generally described this invention, a further
understanding can be obtained by reference to certain specific
examples which are provided herein for purposes of illustration
only, and are not intended to be limiting unless otherwise
specified.
EXAMPLES
Examples 1 and 2 and Comparative Example 1
[0184] A Denison T6C mobile vane pump was operated under the
following controlled conditions:
[0185] Speed=1500 rpm, Pressure=200 bars, Fluid
Temperature=80.degree. C. An ISO VG 46 HM oil was run as a
reference fluid, generated 6.97 kW of hydraulic power.
[0186] By comparison, several ISO VG 46 HV oils were run under the
same conditions, and generated 6 to 11% higher levels of hydraulic
power output, as shown in Table 1.
TABLE-US-00003 TABLE 1 Denison T6C Mobile Vane Pump Power Output
Comparative Example 1 Example 1 Example 2 Fluid Type ISO 46 HM ISO
46 HV ISO 46 HV Viscosity Index 100 150 200 Hydraulic 6.97 7.42
7.74 Power Output, kW Power Output 6.6% 11.1% Increase, % Operating
Conditions: 1500 rpm, 200 bars, 80.degree. C.
Examples 3 to 5 and Comparative Example 2
[0187] An Eaton-Vickers V20 vane pump was operated under the
following controlled conditions: Speed=1200 rpm, Pressure=138 bars,
Fluid Temperature=80.degree. C.
[0188] An ISO VG 46 HM oil was run as a reference fluid, generated
8.69 kW of hydraulic power.
[0189] By comparison, several ISO VG 46 HV oils were run under the
same conditions, and generated 3 to 6% higher levels of hydraulic
power output, as shown in Table 2.
TABLE-US-00004 TABLE 2 Eaton-Vickers V20 Vane Pump Power Output
Comparative Example 2 Example 3 Example 4 Example 5 Fluid Type ISO
46 HM ISO 46 HV ISO 46 HV ISO 46 HV Viscosity Index 100 160 180 200
Hydraulic 8.69 9.01 9.09 9.16 Power Output, kW Power Output 3.8%
4.6% 5.5% Increase, % Operating Conditions: 1200 rpm, 138 bars,
80.degree. C.
Examples 6 to 8 and Comparative Example 3
[0190] An Eaton-Vickers V104C vane pump was operated under the
following controlled conditions:
[0191] Speed=1200 rpm, Pressure=138 bars, Fluid
Temperature=80.degree. C. An ISO VG 46 HM oil was run as a
reference fluid, generated 8.35 kW of hydraulic power.
[0192] By comparison, several ISO VG 46 HV oils were run under the
same conditions, and generated 5 to 7% higher levels of hydraulic
power output, as shown in Table 3.
TABLE-US-00005 TABLE 3 Eaton-Vickers V104C Vane Pump Power Output
Comparative Example 3 Example 6 Example 7 Example 8 Fluid Type ISO
46 HM ISO 46 HV ISO 46 HV ISO 46 HV Viscosity Index 100 160 180 200
Hydraulic 8.35 8.76 8.86 8.95 Power Output, kW Power Output 4.9%
6.0% 7.2% Increase, % Operating Conditions: 1200 rpm, 138 bars,
80.degree. C.
Examples 9 to 11 and Comparative Example 4
[0193] A Komatsu 35+35 dual piston pump was operated under the
following controlled conditions:
[0194] Speed=2100 rpm, Pressure=350 bars, Fluid
Temperature=100.degree. C. An ISO VG 46 HM oil was run as a
reference fluid, generated 5.83 kW of hydraulic power.
[0195] By comparison, several ISO VG 46 HV oils were run under the
same conditions, and generated 4 to 6% higher levels of hydraulic
power output, as shown in Table 4.
TABLE-US-00006 TABLE 4 Komatsu 35 + 35 Dual Piston Pump Power
Output Comparative Example 4 Example 9 Example 10 Example 11 Fluid
Type ISO 46 HM ISO 46 HV ISO 46 HV ISO 46 HV Viscosity Index 100
160 180 200 Hydraulic 5.83 6.07 6.13 6.18 Power Output, kW Power
Output 4.0% 5.0% 6.0% Increase, % Operating Conditions: 2100 rpm,
350 bars, 100.degree. C.
Examples 12 to 14 and Comparative Example 5
[0196] An Eaton L2 gear pump was operated under the following
controlled conditions:
[0197] Speed=2750 rpm, Pressure=207 bars, Fluid
Temperature=80.degree. C. An ISO VG 46 HM oil was run as a
reference fluid, generated 21.5 kW of hydraulic power.
[0198] By comparison, several ISO VG 46 HV oils were run under the
same conditions, and generated 6 to 8.8% higher levels of hydraulic
power output, as shown in Table 5. The pump flow rate and the power
output data were provided by the manufacturer and the increase in
power output was calculated compared to Comparative Example 5.
TABLE-US-00007 TABLE 5 Eaton L2 Gear Pump Power Output Comparative
Example 5 Example 12 Example 13 Example 14 Fluid Type ISO 46 HM ISO
46 HV ISO 46 HV ISO 46 HV Viscosity Index 100 160 180 200 Hydraulic
21.5 22.8 23.2 23.4 Power Output, kW Power Output 6.0% 7.5% 8.8%
Increase, % Operating Conditions: 2750 rpm, 207 bars, 80.degree.
C.
[0199] The data gathered in the examples demonstrate that the "HV"
multigrade oil formulated with Group II PAMA was responsible for
increased hydraulic power output from the hydraulic pumps. The
increased work output allowed the excavator to complete the work
cycle in a shorter period of time, and thus complete higher levels
of work output in equivalent periods of time.
Examples 15 to 18 and Comparative Example 6
[0200] A further advantage of the present invention is to design a
hydraulic system that operates at a lower pressure level and
delivers an equivalent amount of hydraulic power output. Table 6
contains data comparing the relative power input and hydraulic
power output in a Denison P09 piston pump at about 5000 psi (345
bar). The pump flow rate and the power output data were provided by
the manufacturer and the increase in power output was calculated
compared to Comparative Example 6.
TABLE-US-00008 TABLE 6 Comparison of Piston Pump Power Output at
Lower Pressure % Change % Change Flow Rate, Power Overall Power
Overall Pressure, psi gpm In, kW Efficiency In Efficiency
Comparative 5000, 46.76 156.2 79.5 Example 6 Monograde Example 15
5000 psi, 48.87 149.9 82.9 -4.1 4.3 MEHF Example 16 4950 psi, 48.96
148.2 83 -5.2 4.4 MEHF Example 17 4750 psi, 49.31 141.2 83.5 -9.6
5.0 MEHF Example 18 4500 psi, 49.75 132.8 84.2 -15.0 5.9 MEHF
Hydraulic % Change Power % Change in power power (kW) power out
out/power in out/power in Comparative 101.72 0.651 Example 6
Example 15 106.31 4.5 0.709 8.9 Example 16 105.44 3.7 0.712 9.3
Example 17 101.90 0.2 0.722 10.8 Example 18 97.40 -4.2 0.733
12.6
[0201] The data was also expressed graphically in FIG. 1, and
demonstrated that a system can be designed to operate at a 5% lower
pressure level which delivers an equivalent level of hydraulic
power output.
Examples 19 to 22 and Comparative Example 7
[0202] A further experiment showed the improvement of the relative
power input and hydraulic power output in a Denison T6C vane pump
at about 3000 psi. (207 bar) being achieved by the present
invention. The results achieved are shown in Table 7. Additionally,
the data is also expressed graphically in FIG. 2, and demonstrated
that a system can be designed to operate at a 6% lower pressure
level which delivers an equivalent level of hydraulic power
output.
TABLE-US-00009 TABLE 7 Comparison of Vane Pump Power Output at
Lower Pressure % Change % Change Flow Rate, Power Overall Power
Overall Pressure, psi lpm In, kW Efficiency In Efficiency
Comparative 3000, 50.45 24.86 70.01 Example 7 Monograde Example 19
3000 psi, 52.56 24.95 72.68 0.4 3.8 MEHF Example 20 2970 psi, 52.72
24.71 72.88 -0.6 4.1 MEHF Example 21 2850 psi, 53.32 23.78 73.61
-4.3 5.1 MEHF Example 22 2700 psi, 54.15 22.49 74.63 -9.5 6.6 MEHF
% Change Hydraulic Power % Change in power power (kW) power out
out/power in out/power in Comparative 16.82 0.676 Example 7 Example
19 17.52 4.2 0.702 3.8 Example 20 17.40 3.5 0.704 4.1 Example 21
16.88 0.4 0.710 5.0 Example 22 16.25 -3.4 0.722 6.8
* * * * *