GB1601974A - Hydraulic fluids and vehicle suspension units using the fluids - Google Patents
Hydraulic fluids and vehicle suspension units using the fluids Download PDFInfo
- Publication number
- GB1601974A GB1601974A GB22965/78A GB2296578A GB1601974A GB 1601974 A GB1601974 A GB 1601974A GB 22965/78 A GB22965/78 A GB 22965/78A GB 2296578 A GB2296578 A GB 2296578A GB 1601974 A GB1601974 A GB 1601974A
- Authority
- GB
- United Kingdom
- Prior art keywords
- hydraulic fluid
- fluid composition
- cylinder member
- vehicle suspension
- piston assembly
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000012530 fluid Substances 0.000 title claims description 99
- 239000000725 suspension Substances 0.000 title claims description 17
- 239000000203 mixture Substances 0.000 claims description 69
- 238000007906 compression Methods 0.000 claims description 40
- 230000006835 compression Effects 0.000 claims description 40
- 230000035939 shock Effects 0.000 claims description 37
- 239000006096 absorbing agent Substances 0.000 claims description 36
- 229920000642 polymer Polymers 0.000 claims description 18
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 14
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 claims description 12
- 125000004181 carboxyalkyl group Chemical group 0.000 claims description 11
- 125000003118 aryl group Chemical group 0.000 claims description 10
- 239000004215 Carbon black (E152) Substances 0.000 claims description 7
- -1 carboxy imide Chemical class 0.000 claims description 7
- 229930195733 hydrocarbon Natural products 0.000 claims description 7
- 150000002430 hydrocarbons Chemical class 0.000 claims description 7
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 6
- 125000005462 imide group Chemical group 0.000 claims description 6
- 239000012188 paraffin wax Substances 0.000 claims description 5
- 125000005250 alkyl acrylate group Chemical group 0.000 claims description 4
- 229920001897 terpolymer Polymers 0.000 claims description 4
- 230000001629 suppression Effects 0.000 description 6
- 239000003921 oil Substances 0.000 description 5
- 238000010276 construction Methods 0.000 description 4
- 239000004034 viscosity adjusting agent Substances 0.000 description 4
- PAYRUJLWNCNPSJ-UHFFFAOYSA-N Aniline Chemical compound NC1=CC=CC=C1 PAYRUJLWNCNPSJ-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000013016 damping Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 239000003112 inhibitor Substances 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 229920002367 Polyisobutene Polymers 0.000 description 1
- YSMRWXYRXBRSND-UHFFFAOYSA-N TOTP Chemical compound CC1=CC=CC=C1OP(=O)(OC=1C(=CC=CC=1)C)OC1=CC=CC=C1C YSMRWXYRXBRSND-UHFFFAOYSA-N 0.000 description 1
- QCJQWJKKTGJDCM-UHFFFAOYSA-N [P].[S] Chemical compound [P].[S] QCJQWJKKTGJDCM-UHFFFAOYSA-N 0.000 description 1
- 239000002518 antifoaming agent Substances 0.000 description 1
- 239000002199 base oil Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- HQQADJVZYDDRJT-UHFFFAOYSA-N ethene;prop-1-ene Chemical group C=C.CC=C HQQADJVZYDDRJT-UHFFFAOYSA-N 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000010699 lard oil Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002480 mineral oil Substances 0.000 description 1
- 235000010446 mineral oil Nutrition 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229920000193 polymethacrylate Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 239000000276 potassium ferrocyanide Substances 0.000 description 1
- PDEDQSAFHNADLV-UHFFFAOYSA-M potassium;disodium;dinitrate;nitrite Chemical compound [Na+].[Na+].[K+].[O-]N=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O PDEDQSAFHNADLV-UHFFFAOYSA-M 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/006—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium characterised by the nature of the damping medium, e.g. biodegradable
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M149/00—Lubricating compositions characterised by the additive being a macromolecular compound containing nitrogen
- C10M149/02—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C10M149/06—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing monomers having an unsaturated radical bound to an amido or imido group
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
- C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
- C10M2205/04—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing aromatic monomers, e.g. styrene
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
- C10M2207/40—Fatty vegetable or animal oils
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
- C10M2207/40—Fatty vegetable or animal oils
- C10M2207/404—Fatty vegetable or animal oils obtained from genetically modified species
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2217/00—Organic macromolecular compounds containing nitrogen as ingredients in lubricant compositions
- C10M2217/02—Macromolecular compounds obtained from nitrogen containing monomers by reactions only involving carbon-to-carbon unsaturated bonds
- C10M2217/024—Macromolecular compounds obtained from nitrogen containing monomers by reactions only involving carbon-to-carbon unsaturated bonds containing monomers having an unsaturated radical bound to an amido or imido group
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2217/00—Organic macromolecular compounds containing nitrogen as ingredients in lubricant compositions
- C10M2217/02—Macromolecular compounds obtained from nitrogen containing monomers by reactions only involving carbon-to-carbon unsaturated bonds
- C10M2217/028—Macromolecular compounds obtained from nitrogen containing monomers by reactions only involving carbon-to-carbon unsaturated bonds containing monomers having an unsaturated radical bound to a nitrogen-containing hetero ring
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2217/00—Organic macromolecular compounds containing nitrogen as ingredients in lubricant compositions
- C10M2217/06—Macromolecular compounds obtained by functionalisation op polymers with a nitrogen containing compound
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2223/00—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions
- C10M2223/02—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions having no phosphorus-to-carbon bonds
- C10M2223/04—Phosphate esters
- C10M2223/041—Triaryl phosphates
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2223/00—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions
- C10M2223/02—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions having no phosphorus-to-carbon bonds
- C10M2223/04—Phosphate esters
- C10M2223/045—Metal containing thio derivatives
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
- C10N2010/00—Metal present as such or in compounds
- C10N2010/04—Groups 2 or 12
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
- C10N2040/00—Specified use or application for which the lubricating composition is intended
- C10N2040/08—Hydraulic fluids, e.g. brake-fluids
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Fluid-Damping Devices (AREA)
Description
(54) IMPROVED HYDRAULIC FLUIDS,
AND VEHICLE SUSPENSION UNITS USING THE FLUIDS
(71) We, MAREMONT CORPORATION, a corporation organised under the laws of the State of Delaware, U.S.A., of 200 East Randolph Drive, Chicago, State of Illinois,
United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:
This invention relates to hydraulic fluids, and to vehicle suspension units such as shock absorber units using the fluids for noise suppressant purposes.
Shock absorber units of a vehicle have an important role in relation to safety of driving (road holding) and to comfort of passengers. Car manufacturers are more and more conscious of this aspect and are tightening their quality requirements for shock absorbers.
Some of these requirements have appeared rather recently: for instance, the reduction of the noise emission of the shock absorber in service. They are due to new car designs which install the shock absorber in such a way that its noise may be "amplified" by the car body, making motoring uncomfortable for passengers. Oil is an important component in a shock absorber. It works in conjunction with mechanical parts to insure the damping function.
Among the more difficult problems of shock absorbers to handle are those related to noise generation.
Dalibert "Progress in Shock Absorber Oil Technology" in Society of Automotive
Engineers paper 770850, delivered at the S.A.E Passenger Car Meeting held in Detroit,
Michigan on September 26-30, 1977, discusses these various problems, including those involved in noise generation including both low frequency noise (grunching) and high frequency noise (hissing). Dalibert states that "It has been shown that friction characteristics have an influence on low frequency noise; friction modification is therefore a means of controlling this typical noise (grunching). The case of high frequency noise generation is more difficult to suppress.
In regard to high frequency noise emission Dalibert reached the conclusion: "The key to high frequency noise emission is in the mechanical design of the shock absorber; the oil manufacture cannot improve this characteristic by modifying the oil composition"; and further stated: "The shock absorber oil can entirely suppress the low frequency noise but an improvement of the shock absorbed design is necessary to reduce the high frequency noise".
Accordingly it is an object of the present invention to provide a hydraulic fluid with good noise suppression properties.
Another object of the present invention is to provide a vehicle suspension unit or a shock absorber unit containing a hydraulic fluid for suppression of high frequency noise by the inclusion of a specific type of viscosity improver in the hydraulic fluid.
According to one aspect thereof, the invention provides a hydraulic fluid composition including 1 to 10% based on the total weight of the hydraulic fluid composition, of a viscosity index improver which is a carbon chain polymer containing aromatic, carboxy alkyl and carboxy imide groups in the side chains.
Preferably the hydraulic fluid composition has a maximum viscosity of 7000 centistokes, preferably not over 3000 centistokes at - 400F.
According to another aspect thereof, the invention provides a vehicle suspension unit, for example, a shock absorber unit, comprising telescopic parts adapted to be mounted between the sprung and unsprung masses for extending and retracting telescopic movements with respect to one another in response to vertical relative movements between said sprung and unsprung masses, said telescoptic parts defining a plurality of chambers at least one of which varies in volume in response to the telescoptic movement of said parts, hydraulic fluid composition within said chambers movable therebetween in response to the telescoptic movement of said parts and flow restriction means for controlling the flow of the hydraulic fluid composition between said chambers, said hydraulic fluid composition including 1 to 10%, based on the total weight of the hydraulic fluid composition, of a viscosity index improver which is a carbon chain polymer containing aromatic, carboxy alkyl and carboxy imide groups in the side chains.
According to yet another aspect thereof, the invention provides a vehicle suspension unit, for example a shock absorber unit, comprising:
a cylinder member,
a piston assembly having an axis aligned with the axis of said cylinder member and
a piston rod fixed to said piston assembly and extending axially therefrom outwardly of one end of said cylinder member disposed upwardly when said shock absorber is operatively mounted,
a tube surrounding said cylinder member the interior of which defines with the exterior of said cylinder member an annular reservoir chamber,
a seal assembly fixedly connecting the upper end of said cylinder member to the upper end of said intermediate tube and slidably sealingly receiving said piston rod therethrough so as to define the upper end of a rebound chamber within said cylinder member the lower end of which is defined by the piston assembly and the volume of which is variable depending upon the position of sliding movement of said piston assembly within said cylinder member,
a base and end cap assembly fixedly connecting the lower end of said cylinder member and said tube so as to define the lower end of a compression chamber within said cylinder member the upper end of which is defined by the piston assembly and the volume of which is variable depending upon the position of sliding movement of said piston assembly within said cylinder member, said base and end cap assembly including a fixed base member,
a hydraulic fluid composition filling said rebound and compression chambers and partially filling said reservoir chamber,
means on said piston assembly providing for the controlled restricted flow of hydraulic fluid composition from said compression chamber to said rebound chamber during the compression movement of said piston member toward said other end of said cylinder member and from said rebound chamber to said compression chamber during the rebound movement of said piston member toward said seal assembly,
compression valve means in said base member providing for controlled flow of hydraulic fluid composition from said compression chamber to said reservoir chamber during said compression movement and
replenishing valve means in said base member for enabling hydraulic fluid composition to flow from said reservoir chamber to said compression chamber during a rebound movement of said piston assembly toward said seal assembly,
said hydraulic fluid composition including 1 to 10% based on the total weight of the hydraulic fluid composition of a viscosity index improver which is a carbon chain polymer containing aromatic, carboxy alkyl and carboxy imide side chairs.
A specific embodiment of the invention will now be described by way of example, with reference to the accompanying drawing in which the sole figure is a vertical sectional view of one form of a shock absorber unit using the hydraulic fluid composition of the present invention.
Referring to the drawing, the shock absorber unit shown therein is generally indicated by the reference numeral 10. The shock absorber unit 10 is an exemplary structure of the twin tube type to which the improvements of the present invention have been applied. It will be understood that the improvements of the present invention are equally applicable to twin tube shock absorber units of other specific constructions, single tube shock absorber units as well as spring units having damping function, as for example, hydropneumatic struts, combined shock absorber and spring units of the coil, pneumatic. or liquid type.
The shock absorber unit 10 which is illustrated in the drawing for purpose of providing a specific exemplary embodiment of the present invention includes the usual inner tube or cvlinder member 12 within which is slidably mounted a piston assembly, generally indicated at 14. A piston rod 16 is fixedly connected with the piston assembly 14 and extends axially therefrom outwardly through one end of the cylinder member. An intermediate tube 18 is disposed in surrounding relation with the cylinder member 12. The interior of the intermediate tube defines with the exterior of the cylinder member an annular reservoir chamber 20.
Fixedly connected with the upper end of the cylinder member 12 and the upper end of the intermediate tube 18 is a seal assembly, generally indicated at 22, which serves to slidably receive the piston rod 16 therethrough. The seal assembly is of conventional construction and serves to enclose the upper end of the reservoir chamber 20 and to define the upper end of a rebound chamber 24 within the cylinder member 12, the lower end of which is defined by the piston assembly 14. The volume of the rebound chamber 24 is thus variable depending upon the position of the sliding movement of the piston assembly 14 within the cylinder member 12, as is well known in the art.
The base and end cap assembly, generally indicated at 26, is fixedly connected with the lower end of the cylinder 12 and intermediate tube 18. The base and end cap assembly 26 serves to partially enclose the lower end of the reservoir chamber 20 and to provide for controlled communication thereof with the lower end of a compression chamber 28 within the cylinder member 12, the lower end of which is defined by the base and end cap assembly and the upper end of which is defined by the piston assembly 14. The compression chamber 28 is variable in volume, depending upon the position of sliding movement of the piston assembly 14 within the cylinder member 12.
The shock absorber unit 10 also includes the usual outer dust tube 30, the upper end of which is suitably connected with the outer end of the piston rod 16. It will be understood, however, that in accordance with conventional procedure the dust tube may be eliminated where required to suit the particular installation. As shown, this connection is effected by an end cap 32 to which is rigidly secured a mounting connector 34. The connector 34 may be of any conventional configuration, such as the ring, as shown, or a stud. A similar mounting connector 36 is fixedly secured to the exterior of the base and end cap assembly 26. Other mounting arrangement rendering the shock absorber unit suitable for use in a McPherson strut assembly may be employed. In accordance with conventional practice, the shock absorber unit 10, when mounted in operative relation on a vehicle, is generally oriented so that the connector 34 secured to the outer end of the piston rod 16 is disposed upwardly while the other connector is oriented in a downward position with respect thereto.
It will be understood that the shock absorber unit 10 is also provided with hydraulic fluid composition formulated in accordance with the principles of the present invention which fills both the rebound and compression chamber 24 and 28 and partially fills the replenishing or reservoir chamber 20. In accordance with conventional practice, the riding characteristics of the shock absorber unit are determined by controlling the flow of hydraulic fluid composition between the various chambers during the telescopic movements of the shock absorber unit occasioned by the relative movement of the sprung and unsprung masses of the vehicle. Compression control of the hydraulic fluid composition is accomplished when the piston assembly 14 is moved in a downward direction causing the compression chamber 28 to reduce the volume and the rebound chamber 24 to increase in volume. Control of the flow of hydraulic fluid composition from the reducing volume compression chamber to the increasing volume rebound chamber is provided by an annular valve assembly 38 mounted on the periphery of the piston assembly 14 and disposed in flow control relation with the interior of the cylinder member 12. Here again, the construction of the piston compression valve assembly 38 is of a conventional nature. Since the rebound chamber 24 contains the piston rod and the compression chamber does not, the differential volume of hydraulic fluid composition in decreasing volume compression chamber 28 must pass to the reservoir chamber 0. Control of this flow is accomplished by a compression valve assembly 40 mounted in the base and end cap assembly 26.
Rebound control is accomplished when the piston assembly 14 moves upwardly within the cylinder member 12. Under these circumstances hydraulic fluid composition must pass from the decreasing volume rebound chamber 24 into the increasing volume compression chamber 28. Here again, because of the piston rod displacement, additional hydraulic fluid composition must be introduced into the increasing volume compression chamber and such hydraulic fluid composition comes from the replenishing or reservoir chamber 20. Control of the latter flow is accomplished by means of a replenishing valve 42 mounted in the base and end cap assembly 26. Replenishing valve 42 is of conventional construction and its seat may be provided with bleed passages in accordance with known practice for providing fixed compression control bleed openings.
It has now been found that these objects can be attained by the inclusion in the hydraulic fluid composition employed in the shock absorber of a specific type of viscosity modifying agent. namely a carbon chain polymer containing aromatic, carboxy alkyl and carboxy imide groups in the side chains. Such materials are available from The Lubrizol Corp. under the name Lubrizol (Registered Trade Mark) 3700 Series and apparently are terpolymers of styrene, alkyl acrylate and a carboxy imide supplying component. A particularly preferred viscosity modifying agent is Lubrizol 3702 which is a mineral oil sulution of such a carbon chain polymer containing styrene. carboxy alkyl and carboxy imide groups in the side chains. According to trade literature Lubrizol 3702 has a viscosity of 20"F. of 3800 SUS and a nitrogen content of 0.20% by weight.
The viscosity modifier, e.g. Lubrizol 3702, should be employed in an amount of 1 to 10%, preferably 4% based on the weight of the hydraulic fluid composition. Below 1% there is not sufficient improvement in reduction of high frequency noises and above 10% there is the problem that the viscosity of the composition is too high at low temperatures resulting in a ride that is too harsh or stiff at low temperatures. The viscosity of a fluid is a function of the viscosity of each of its constituents. A fluid composition with more than 10% of such a viscosity index improver could, with sufficiently low viscosity base fluids, perform well at low temperatures. Such a fluid, however, would be subject to evaporation at high operating temperatures. Where low temperature or high temperature characteristics are not a major concern, compositions with more than 10% can be used and provide greater noise suppression. Additionally, there is the problem of increased expense as the amount of viscosity modifier is increased. The viscosity at -400F should preferably not be over 7000 centistokes or more preferably not over 3000 centistokes.
There can be employed any of the conventional hydraulic fluids, e.g. paraffin base or solvent refined or mixed base hydraulic fluids. Also there can be included conventional additives such as rust inhibitors, wear improvers and the like.
The presently preferred composition is a blend of:
(a) base fluid which is a paraffin base oil
(b) Hitec (Registered Trade Mark) E536, rust inhibitor, 0.1% by weight
(c) Lard Oil, 2.5% by weight
(d) Tritolyl phosphate, 1.5% by weight
(e) Lubrizol 3702, 4% by weight
(f) Zinc dialkyl dithiophate (wear improver), 0.5% by weight.
The above homogeneous fluid blend also has the following specifications:
1. Flash point 295"F min.
2. Fire point 335"F min.
3. Pour point -850F max.
4. Aniline point 155 - 178"F 5. Suponification number 6
6. Viscosity -400F 3000 centistokes (max.) 100cm 9.7 centistokes (Ref.) 210 F 2.7 centistokes (min.)
7. Gravity A.P.I. 26 - 30
The high frequency noises which are suppressed generally have a frequency of at least 500() Herz.. e.g. 5,000 - 10,000.
Various formulations were tested as additives to hydraulic fluids in addition to the viscosity modifiers of the Lubrizol 3700 series. Thus, there were tried other viscosity modifiers. i.e., viscosity index improvers, e.g. styrene based copolymers, polyisobutylenes, ethylene-propylene polymers and polymethacrylates.
While shock absorber fluid noise is related to fluid turbulence and fluid turbulence is inversely related to fluid visocity, it was found that the effect of viscosity increase plays only a small part in fluid noise suppression. While the viscosity index improvers in general showed some measure of noise suppressions, the performance of Lubrizol 3702 was significantly better than the other viscosity index improvers tested.
These were also tested
1. sulfur-phosphorus friction modifiers,
2. zinc dialkyl dithiophosphate,
3. silicone fluid,
4. anti-foaming agents,
5. other shock absorber fluids,
6. various combinations of the above.
None of these showed any significant noise suppression.
The hydraulic fluid composition can comprise the stated materials. Unless otherwise indicated, all parts and percentages are by weight.
WHAT WE CLAIM IS:
1. A hydraulic fluid composition 1 to 10%, based on the total weight of the hydraulic fluid composition, of a viscosity index improver which is a carbon chain polymer containing aromatic, carboxy alkyl and carboxy imide groups in the side chains.
2. A hydraulic fluid composition according to claim 1, containing about 4% of said polymer.
3. A hydraulic fluid composition according to claim 1, wherein the base hydraulic fluid is a hydrocarbon fluid.
4. A hydraulic fluid composition according to claim 3 wherein the hydrocarbon fluid is a paraffin hydrcarbon fluid.
5. A hydraulic fluid composition according to claim 1, wherein the carbon chain polymer is a terpolymer of styrene, alkyl acrylate and a carboxy imide supplying component.
6. A hydrulic fluid composition according to any one of claims 1 to 5 having a maximum viscosity of 7000 centistokes, preferably not over 3000 centistokes, at - 40"F.
7. A vehicle suspension unit, for example a shock absorber unit, comprising telescopic parts adapted to be mounted between the sprung and unsprung masses for extending and retracting telescopic movements with respect to one another in response to relative vertical movements between said sprung and unsprung masses, said telescopic parts defining a plurality of chambers at least one of which varies in volume in response to the telescopic movement of said parts, hydraulic fluid composition within said chambers movable therebetween in response to the telescopic movement of said parts and flow restriction means for controlling the flow of the hydraulic fluid composition between said chambers, said hydraulic fluid composition including 1 to 10%, based on the total weight of the hydraulic fluid composition, of a viscosity index improver which is a carbon chain polymer containing aromatic, carboxy alkyl and carboxy imide groups- in the side chains.
8. A vehicle suspension unit, for example a shock absorber unit, comprising:
a cylinder member,
a piston assembly having an axis aligned with the axis of said cylinder member and
a piston rod fixed to said piston assembly and extending axially therefrom outwardly of one end of said cylinder member disposed upwardly when said shock absorber is operatively mounted,
a tube surrounding said cylinder member the interior of which defines with the exterior of said cylinder member an annular reservoir chamber,
a seal assembly fixedly connecting the upper end of said cylinder member to the upper end of said intermediate tube and slidably sealingly receiving said piston rod therethrough so as to define the upper end of a rebound chamber within said cylinder member the lower end of which is defined by the piston assembly and the volume of which is variable depending upon the position of sliding movement of said piston assembly within said cylinder member,
a base and end cap assembly fixedly connecting the lower end of said cylinder member and said tube so as to define the lower end of a compression chamber within said cylinder member the upper end of which is defined by the piston assembly and the volume of which is variable depending upon the position of sliding movement of said piston assembly within said cylinder member, said base and end cap assembly including a fixed base member,
a hydraulic fluid composition filling said rebound and compression chambers and partially filling said reservoir chamber,
means on said piston assembly providing for the controlled restricted flow of hydraulic fluid composition from said compression chamber to said rebound chamber during the compression movement of said piston member toward said other end of said cylinder member and from said rebound chamber to said compression chamber during the rebound movement of said piston member toward said seal assembly,
compression valve means in said base member providing for controlled flow of hydraulic fluid composition from said compression chamber to said reservoir chamber during said compression movement and
replenishing valve means in said base member for enabling hydraulic fluid composition to flow from said reservoir chamber to said compression chamber during a rebound movement of said piston assembly toward said seal assembly,
said hydraulic fluid composition including 1 to 10% based on the total weight of the hydraulic fluid composition of a viscosity index improver which is a carbon chain polymer containing aromatic, carboxy alkyl and carboxy imide side chains.
9. A vehicle suspension unit according to claim 7 or claim 8, where the hydraulic fluid composition contains about 4% of said polymer.
10. A vehicle suspension unit according to claim 7 or claim 8, wherein the base
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (14)
1. A hydraulic fluid composition 1 to 10%, based on the total weight of the hydraulic fluid composition, of a viscosity index improver which is a carbon chain polymer containing aromatic, carboxy alkyl and carboxy imide groups in the side chains.
2. A hydraulic fluid composition according to claim 1, containing about 4% of said polymer.
3. A hydraulic fluid composition according to claim 1, wherein the base hydraulic fluid is a hydrocarbon fluid.
4. A hydraulic fluid composition according to claim 3 wherein the hydrocarbon fluid is a paraffin hydrcarbon fluid.
5. A hydraulic fluid composition according to claim 1, wherein the carbon chain polymer is a terpolymer of styrene, alkyl acrylate and a carboxy imide supplying component.
6. A hydrulic fluid composition according to any one of claims 1 to 5 having a maximum viscosity of 7000 centistokes, preferably not over 3000 centistokes, at - 40"F.
7. A vehicle suspension unit, for example a shock absorber unit, comprising telescopic parts adapted to be mounted between the sprung and unsprung masses for extending and retracting telescopic movements with respect to one another in response to relative vertical movements between said sprung and unsprung masses, said telescopic parts defining a plurality of chambers at least one of which varies in volume in response to the telescopic movement of said parts, hydraulic fluid composition within said chambers movable therebetween in response to the telescopic movement of said parts and flow restriction means for controlling the flow of the hydraulic fluid composition between said chambers, said hydraulic fluid composition including 1 to 10%, based on the total weight of the hydraulic fluid composition, of a viscosity index improver which is a carbon chain polymer containing aromatic, carboxy alkyl and carboxy imide groups- in the side chains.
8. A vehicle suspension unit, for example a shock absorber unit, comprising:
a cylinder member,
a piston assembly having an axis aligned with the axis of said cylinder member and
a piston rod fixed to said piston assembly and extending axially therefrom outwardly of one end of said cylinder member disposed upwardly when said shock absorber is operatively mounted,
a tube surrounding said cylinder member the interior of which defines with the exterior of said cylinder member an annular reservoir chamber,
a seal assembly fixedly connecting the upper end of said cylinder member to the upper end of said intermediate tube and slidably sealingly receiving said piston rod therethrough so as to define the upper end of a rebound chamber within said cylinder member the lower end of which is defined by the piston assembly and the volume of which is variable depending upon the position of sliding movement of said piston assembly within said cylinder member,
a base and end cap assembly fixedly connecting the lower end of said cylinder member and said tube so as to define the lower end of a compression chamber within said cylinder member the upper end of which is defined by the piston assembly and the volume of which is variable depending upon the position of sliding movement of said piston assembly within said cylinder member, said base and end cap assembly including a fixed base member,
a hydraulic fluid composition filling said rebound and compression chambers and partially filling said reservoir chamber,
means on said piston assembly providing for the controlled restricted flow of hydraulic fluid composition from said compression chamber to said rebound chamber during the compression movement of said piston member toward said other end of said cylinder member and from said rebound chamber to said compression chamber during the rebound movement of said piston member toward said seal assembly,
compression valve means in said base member providing for controlled flow of hydraulic fluid composition from said compression chamber to said reservoir chamber during said compression movement and
replenishing valve means in said base member for enabling hydraulic fluid composition to flow from said reservoir chamber to said compression chamber during a rebound movement of said piston assembly toward said seal assembly,
said hydraulic fluid composition including 1 to 10% based on the total weight of the hydraulic fluid composition of a viscosity index improver which is a carbon chain polymer containing aromatic, carboxy alkyl and carboxy imide side chains.
9. A vehicle suspension unit according to claim 7 or claim 8, where the hydraulic fluid composition contains about 4% of said polymer.
10. A vehicle suspension unit according to claim 7 or claim 8, wherein the base
hydraulic fluid is a hydrocarbon fluid.
11. A vehicle suspension unit according to calim 10, wherein the hydrocarbon fluid is a paraffin hydrocarbon fluid.
12. A vehicle suspension unit according to claim 7 or claim 8, wherein the carbon chain polymer is a terpolymer of a styrene, alkyl acrylate and a carboxy imide supplying component.
13. A hydraulic fluid according to any one of claims 1 to 6 substantially as hereinbefore described.
14. A vehicle suspension unit according to any one of claims 7 to 12 substantially as hereinbefore described with reference to, and as illustrated in the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US90761778A | 1978-05-19 | 1978-05-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1601974A true GB1601974A (en) | 1981-11-04 |
Family
ID=25424389
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB22965/78A Expired GB1601974A (en) | 1978-05-19 | 1978-05-26 | Hydraulic fluids and vehicle suspension units using the fluids |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS54152762A (en) |
| BE (1) | BE868356A (en) |
| DE (1) | DE2824134A1 (en) |
| GB (1) | GB1601974A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1043474A (en) * | 1996-05-29 | 1998-02-17 | Samsung Electron Co Ltd | Ball balancer |
-
1978
- 1978-05-26 GB GB22965/78A patent/GB1601974A/en not_active Expired
- 1978-06-01 DE DE19782824134 patent/DE2824134A1/en not_active Withdrawn
- 1978-06-22 BE BE188766A patent/BE868356A/en unknown
- 1978-06-29 JP JP7813378A patent/JPS54152762A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| BE868356A (en) | 1978-12-22 |
| JPS54152762A (en) | 1979-12-01 |
| DE2824134A1 (en) | 1979-11-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6390258B1 (en) | Floating rod guide for monotube strut | |
| US4828232A (en) | Vehicle air suspension strut with compliant cover plate assembly | |
| US7950506B2 (en) | Semi third tube design | |
| US6918473B2 (en) | Stroke dependent bypass | |
| US6220409B1 (en) | Stroke dependent bypass | |
| US5984060A (en) | Monotube strut assembly | |
| US7011193B2 (en) | Rod guide and seal system for gas filled shock absorbers | |
| EP1231403B1 (en) | Frequency dependent damper | |
| US6161821A (en) | Hydropneumatic spring strut | |
| GB2402990A (en) | Twin piston shock absorber | |
| CN102307738A (en) | A triple tube shock absorber having a shortened intermediate tube | |
| WO2014149527A1 (en) | Rod guide arrangement for electronically controlled valve applications | |
| US7073643B2 (en) | Compensated rod for a frequency dependent damper shock absorber | |
| US4105193A (en) | Shock absorber and leveling unit with auxiliary damping device for vehicle suspensions | |
| GB2199118A (en) | Hydraulic damper | |
| US12331806B2 (en) | Telescopic passive damper | |
| GB1601974A (en) | Hydraulic fluids and vehicle suspension units using the fluids | |
| JP3351826B2 (en) | Front fork hydraulic shock absorber | |
| US5893436A (en) | One piece aluminum pressure tube with rod guide for shock absorbers | |
| US6364075B1 (en) | Frequency dependent damper | |
| GB2341909A (en) | A frequency dependent fluid damper for a vehicle suspension. | |
| CA2272268A1 (en) | Shock absorber containing biodegradable fluid | |
| US20240288044A1 (en) | Sequential telescopic passive damper | |
| EP4421346A1 (en) | Sequential telescopic passive damper | |
| CN211231399U (en) | Cylinder type shock absorber |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed |