GB2067710A - Vehicle suspension unit containing gas in permeable envelope - Google Patents

Vehicle suspension unit containing gas in permeable envelope Download PDF

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Publication number
GB2067710A
GB2067710A GB8001681A GB8001681A GB2067710A GB 2067710 A GB2067710 A GB 2067710A GB 8001681 A GB8001681 A GB 8001681A GB 8001681 A GB8001681 A GB 8001681A GB 2067710 A GB2067710 A GB 2067710A
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GB
United Kingdom
Prior art keywords
envelope
cylinder
gas
nitrogen
suspension unit
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.)
Withdrawn
Application number
GB8001681A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ZF International UK Ltd
Original Assignee
Lucas Industries Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Lucas Industries Ltd filed Critical Lucas Industries Ltd
Priority to GB8001681A priority Critical patent/GB2067710A/en
Publication of GB2067710A publication Critical patent/GB2067710A/en
Withdrawn legal-status Critical Current

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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
    • F16F9/06—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium using both gas and liquid
    • F16F9/08—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium using both gas and liquid where gas is in a chamber with a flexible wall
    • F16F9/088—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium using both gas and liquid where gas is in a chamber with a flexible wall comprising a gas spring with a flexible wall provided within the cylinder on the piston rod of a monotubular damper or within the inner tube of a bitubular damper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G15/00—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type
    • B60G15/08—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type having fluid spring
    • B60G15/12—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type having fluid spring and fluid damper

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Fluid-Damping Devices (AREA)
  • Vehicle Body Suspensions (AREA)

Abstract

A suspension unit comprises a cylinder 1 having a piston 2 working therein, the piston having a piston rod 3 extending sealingly through one end of the cylinder. The cylinder contains a mixture of liquid and gas, usually nitrogen, under pressure. In order to reduce leakage of nitrogen past the piston rod seal, the cylinder contains an envelope 8 of gas-permeable material which initially contains a large-molecule gas, for example trichloro-fluoro-methane. The nitrogen migrates into the envelope until most of the nitrogen is held therein. Thus, the amount of nitrogen able to leak past the piston rod seal is reduced by the amount within the envelope. <IMAGE>

Description

SPECIFICATION Vehicle suspension unit This invention relates to suspension units for vehicles.
Suspension units commonly comprise a cylinder having one end closed and within which works a damping piston carried by a piston rod.
The piston rod extends through a rod guide and seal at the other end of the cylinder. The unit is commonly filled with pressurised gas, usually nitrogen, and liquid which mix together to form an "emulsion" during use of the unit on a vehicle.
When the vehicle is stationary the liquid and gas tend to separate.
It has been found with such units that after a period of use the pressure within the cylinder reduces. It is believed that such pressure reduction is caused by the leakage of nitrogen molecules between the seal and the piston rod. The migration is possibly caused by slight imperfections in the surface of the piston rod which imperfections permit nitrogen molecules to be carried past the seal by the piston rod.
The aim of the present invention is to reduce such leakage.
In accordance with the present invention, there is provided a suspension unit for a vehicle, comprising a cylinder which is closed at one end and through the other end of which extends a piston rod carrying a damping piston working in the cylinder, and a sealed envelope within the cylinder, the envelope containing gas.
Preferably the envelope initially contains a first, relatively large-molecule gas, such as Arcton, for example trichloro fluoro methane, and the cylinder contains liquid and a second gas, preferably nitrogen, under pressure. The second gas migrates through the envelope, which is a permeable membrane for example of Nylon 11, until all the second gas is either mixed with the liquid or contained within the envelope.
The invention also provides a method of making the suspension unit comprising the steps of partially filling the unit with liquid, locating the envelope containing the large molecuie gas within the cylinder and pressurising the unit with the second gas.
The pressure of the unit is preferably of the order of 300 p.s.i.
A vehicle suspension unit in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is an axial cross-sectional view of the unit upon assembly, and Figure 2 is a view similar to Figure 1 of the unit after a period of time.
The suspension unit comprises a cylinder 1 within which works a valved damping piston 2 carried by a piston rod 3 extending through a rod guide 4 and seal 5. The outer end (not shown) of the rod and the lower end 6 of the cylinder 1 have mounting eyes 7 for mounting the unit on a vehicle.
Located in the cylinder 1 above the piston 2 is a sealed envelope 8 which contains a gas, such as Arcton, e.g. trichloro fluoro methane, having a molecule size greater than that of nitrogen. The envelope is made of gas-permeable material such as Nylon 11 and is annular in transverse crosssection and surrounds the piston rod 3. Between the piston rod 3 and the envelope 8 is a cylindrical member 9 which serves both to protect the envelope and as a rebound stop for the piston 2.
To assemble the unit, liquid is placed in the cylinder 1 and the piston 2 and piston rod 3 inserted, the gas-filled envelope 8 and member 9 are positioned around the rod 3 and the seal 5 and rod guide 4 secured in the end of the cylinder.
Nitrogen is inserted through an injection aperture 10 at high pressure until the pressure within the cylinder is about 300 p.s.i., the aperture 10 then being closed by a plug 11 (Figure 2).
Because of the pressure differential across the envelope, nitrogen migrates into the envelope until eventually, preferably within the storage period of the unit before it is fitted to the vehicle, most of the nitrogen is within the envelope. In use of the unit, any nitrogen not within the envelope will mix with the liquid to form an "emulsion".
Thus, little nitrogen is outside the envelope and the possibility of leakage Dast the seal is considerably reduced.
In order to reduce the risk of liquefaction of the Arcton and collapsing of the envelope when the working pressure in the cylinder is very high during use, the envelope 8 is preferably provided with a non-collapsible structure 12 which may, as shown, take the form of a rigid member in the form of a sphere and some other shape.
Alternatively, the envelope could be supported by, for example, a mesh structure to prevent collapsing.
1. A suspension unit for a vehicle, comprising a cylinder which is closed at one end and through the other end of which sealingly extends a piston rod carrying a piston working in the cylinder, and a sealed envelope within the cylinder, the envelope containing gas.
2. A suspension unit according to claim 1, wherein the envelope contains a large-molecule gas.
3. A suspension unit according to claim 2, wherein the gas is Arcton.
4. A suspension unit according to claim 3, wherein the gas is trichloro-fluoro-methane.
5. A suspension unit according to any of claims 1 to 4, wherein the cylinder contains a pressurised liquid and gas mixture.
6. A suspension unit according to claim 5, wherein the gas of the mixture is nitrogen.
7. A suspension unit according to claim 5 or 6, wherein the envelope is made of a material which is permeable by the gas of the mixture.
8. A method of making a suspension unit according to claim 1, comprising the steps of partially filling the cylinder with liquid, locating the
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Vehicle suspension unit This invention relates to suspension units for vehicles. Suspension units commonly comprise a cylinder having one end closed and within which works a damping piston carried by a piston rod. The piston rod extends through a rod guide and seal at the other end of the cylinder. The unit is commonly filled with pressurised gas, usually nitrogen, and liquid which mix together to form an "emulsion" during use of the unit on a vehicle. When the vehicle is stationary the liquid and gas tend to separate. It has been found with such units that after a period of use the pressure within the cylinder reduces. It is believed that such pressure reduction is caused by the leakage of nitrogen molecules between the seal and the piston rod. The migration is possibly caused by slight imperfections in the surface of the piston rod which imperfections permit nitrogen molecules to be carried past the seal by the piston rod. The aim of the present invention is to reduce such leakage. In accordance with the present invention, there is provided a suspension unit for a vehicle, comprising a cylinder which is closed at one end and through the other end of which extends a piston rod carrying a damping piston working in the cylinder, and a sealed envelope within the cylinder, the envelope containing gas. Preferably the envelope initially contains a first, relatively large-molecule gas, such as Arcton, for example trichloro fluoro methane, and the cylinder contains liquid and a second gas, preferably nitrogen, under pressure. The second gas migrates through the envelope, which is a permeable membrane for example of Nylon 11, until all the second gas is either mixed with the liquid or contained within the envelope. The invention also provides a method of making the suspension unit comprising the steps of partially filling the unit with liquid, locating the envelope containing the large molecuie gas within the cylinder and pressurising the unit with the second gas. The pressure of the unit is preferably of the order of 300 p.s.i. A vehicle suspension unit in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is an axial cross-sectional view of the unit upon assembly, and Figure 2 is a view similar to Figure 1 of the unit after a period of time. The suspension unit comprises a cylinder 1 within which works a valved damping piston 2 carried by a piston rod 3 extending through a rod guide 4 and seal 5. The outer end (not shown) of the rod and the lower end 6 of the cylinder 1 have mounting eyes 7 for mounting the unit on a vehicle. Located in the cylinder 1 above the piston 2 is a sealed envelope 8 which contains a gas, such as Arcton, e.g. trichloro fluoro methane, having a molecule size greater than that of nitrogen. The envelope is made of gas-permeable material such as Nylon 11 and is annular in transverse crosssection and surrounds the piston rod 3. Between the piston rod 3 and the envelope 8 is a cylindrical member 9 which serves both to protect the envelope and as a rebound stop for the piston 2. To assemble the unit, liquid is placed in the cylinder 1 and the piston 2 and piston rod 3 inserted, the gas-filled envelope 8 and member 9 are positioned around the rod 3 and the seal 5 and rod guide 4 secured in the end of the cylinder. Nitrogen is inserted through an injection aperture 10 at high pressure until the pressure within the cylinder is about 300 p.s.i., the aperture 10 then being closed by a plug 11 (Figure 2). Because of the pressure differential across the envelope, nitrogen migrates into the envelope until eventually, preferably within the storage period of the unit before it is fitted to the vehicle, most of the nitrogen is within the envelope. In use of the unit, any nitrogen not within the envelope will mix with the liquid to form an "emulsion". Thus, little nitrogen is outside the envelope and the possibility of leakage Dast the seal is considerably reduced. In order to reduce the risk of liquefaction of the Arcton and collapsing of the envelope when the working pressure in the cylinder is very high during use, the envelope 8 is preferably provided with a non-collapsible structure 12 which may, as shown, take the form of a rigid member in the form of a sphere and some other shape. Alternatively, the envelope could be supported by, for example, a mesh structure to prevent collapsing. CLAIMS
1. A suspension unit for a vehicle, comprising a cylinder which is closed at one end and through the other end of which sealingly extends a piston rod carrying a piston working in the cylinder, and a sealed envelope within the cylinder, the envelope containing gas.
2. A suspension unit according to claim 1, wherein the envelope contains a large-molecule gas.
3. A suspension unit according to claim 2, wherein the gas is Arcton.
4. A suspension unit according to claim 3, wherein the gas is trichloro-fluoro-methane.
5. A suspension unit according to any of claims 1 to 4, wherein the cylinder contains a pressurised liquid and gas mixture.
6. A suspension unit according to claim 5, wherein the gas of the mixture is nitrogen.
7. A suspension unit according to claim 5 or 6, wherein the envelope is made of a material which is permeable by the gas of the mixture.
8. A method of making a suspension unit according to claim 1, comprising the steps of partially filling the cylinder with liquid, locating the envelope containing a large-molecule gas within the cylinder and pressurising the unit with another gas.
9. A suspension unit constructed and arranged substantially as herein described with reference to the accompanying drawings.
10. A method of making a suspension unit according to claim 8 and substantially as herein described.
GB8001681A 1980-01-18 1980-01-18 Vehicle suspension unit containing gas in permeable envelope Withdrawn GB2067710A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8001681A GB2067710A (en) 1980-01-18 1980-01-18 Vehicle suspension unit containing gas in permeable envelope

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8001681A GB2067710A (en) 1980-01-18 1980-01-18 Vehicle suspension unit containing gas in permeable envelope

Publications (1)

Publication Number Publication Date
GB2067710A true GB2067710A (en) 1981-07-30

Family

ID=10510719

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8001681A Withdrawn GB2067710A (en) 1980-01-18 1980-01-18 Vehicle suspension unit containing gas in permeable envelope

Country Status (1)

Country Link
GB (1) GB2067710A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2508581A1 (en) * 1981-06-27 1982-12-31 Stabilus Gmbh PNEUMATIC OR HYDRO PNEUMATIC CYLINDER PISTON ASSEMBLY, SUCH AS A DAMPER, COMPONENT OF AN ELASTIC FORCE LEG FOR A VEHICLE OR GAS SPRING
GB2156944A (en) * 1984-04-03 1985-10-16 George Bertram Powell Monotube shock absorber
DE102009008336B3 (en) * 2009-02-10 2010-09-16 Zf Friedrichshafen Ag Vibration damper i.e. tubular damper, has sleeve provided with inner and outer rings, and elastomer part arranged between inner and outer rings, where flexible element is accommodated within elastomer part

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2508581A1 (en) * 1981-06-27 1982-12-31 Stabilus Gmbh PNEUMATIC OR HYDRO PNEUMATIC CYLINDER PISTON ASSEMBLY, SUCH AS A DAMPER, COMPONENT OF AN ELASTIC FORCE LEG FOR A VEHICLE OR GAS SPRING
GB2156944A (en) * 1984-04-03 1985-10-16 George Bertram Powell Monotube shock absorber
DE102009008336B3 (en) * 2009-02-10 2010-09-16 Zf Friedrichshafen Ag Vibration damper i.e. tubular damper, has sleeve provided with inner and outer rings, and elastomer part arranged between inner and outer rings, where flexible element is accommodated within elastomer part

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)