Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
  • F15B15/20—Other details, e.g. assembly with regulating devices
  • F15B15/22—Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke

Definitions

• This invention relates to a fluid jack, and more particularly to a self-contained cushioning device floatingly positioned within a cylinder of the fluid jack between a closed end of the cylinder and a piston.
• the components of the heretofore known cushioning devices have been included as integral por ⁇ tions of existing major components of the fluid jacks.
• providing a cushioning device for a specific fluid jack required redesigning some of the major components of the fluid jack.
• to insure proper alignment of the mating parts requires exacting machining toleran ⁇ ces .and consequently more precise machining of the components.
• replacing a damaged component of the cushioning device also requires replacing one of the major components of the fluid jack.
• the invention solves the problem of having to redesign some of the major components of a fluid jack to provide a cushioning device therefor by constructing th cushioning device as a self-contained unit which can be floatingly positioned within a cylinder of the fluid jack between a closed end thereof and the piston.
• a fluid jack has a piston reciprocatably positioned within a cylinder and movable toward and away from a closed end of the cylinder and a cushioning device floatingly positioned within the cylinder between the piston and the closed end of the cylinder, said- cushion ing device has a first member slidably positioned withi the cylinder and has a bore therein, a second member is slidably positioned within said bore, means forms a variable volume chamber between said first and ' second members, and means meters fluid from said chamber in response to relative movement between said first and second members in a direction for decreasing the volume of said variable volume chamber.
• a fluid jack 10 has a cylinder 11 and piston means 12 reciprocatably positioned within the cylinder and movable toward and away from a closed end 13 of the cylinder.
• The-piston means 12 includes a piston 14 separating the cylinder into first and second chambers 16,17 and a piston rod 18 slidably extending through an end cap 19 and having an end connected to the piston.
• a cushioning device 21 is floatingly posi ⁇ tioned within the first chamber 16 of cylinder 11 between the closed end 13 and piston means 12.
• the cushioning device includes first and second members
• variable volume chamber between the first and second members
• means 27 for metering fluid from the variable volume chamber in response to relative movement between the first and second members in a direction for decreasing the volume of the variable volume chamber.
• the first member 22 has an axially extending bore 28 and a pair of axially spaced annular grooves 29 in the outer peripheral surface thereof.
• a pair of wear rings 31 are individually seated in the grooves for sliding engagement with the inner surface of cylinder 11.
• a plurality of transverse grooves 32 in an end surface 33 connect with an axially extending passage 34.
• the second member 23 is slidably positioned within bore 28 and is retained therein by a ring 36 seated in an annular groove in the bore 28.
• a spring 37 resiliently urges the second member against ring 36.
• a transverse groove 38 in an end surface 39 of the second member communicates with an axially extending passage 41.
• the means 26 includes third and fourth elon ⁇ gate tubular members 42,43.
• the third member has a flanged end 44 sealingly seated within a counterbdre of the second member 23.
• a bore 46 extends through the third member in axial alignment with the passage 41.
• the fourth member 43 is telescopically positioned within bore 46 of third member 42 and has a flanged end 47 sealingly seated within a counterbore in first member 22.
• a bore 48 in the fourth member is in axial align ⁇ ment with passage 34.
• a spring 49 resiliently maintains the flanged ends 44,47 seated within the counterbores of the first and second members respectively.
• the means 27 includes a plurality of axially spaced orifices 51 extending through the wall of fourth member 43 and communicates the variable volume chamber 24 with the bore 48.
• the orifices are positioned to be sequentially closed by fourth member 43 in response to movement of first and second members 22,23 in a direc ⁇ tion for decreasing the volume of the variable volume chamber. The sequential closing of the orifices thereby progressively restricts the escape of fluid from the variable volume chamber.
• a passage means 52 for passing fluid through the cushioning device 21 from one end to the other includes grooves 32, passage 34, bores 48,46, passage 41, and groove 38.
• first chamber 16 is vented"to tank while fluid under pressure is directed to second chamber 17 in any suitable manner, not shown, which causes piston means 12 to move downwardly toward closed end 13.
• gravitational or other forces acting on the piston rod 18 can cause the piston means 12 to descend quite rapidly, generating high inertia forces.
• Such movement of the second and third members 23,42 is dependent upon the rate at which fluid is expelled from the variable volume chamber 24.
• third member 42 moves downwardly, the lower end thereof sequentially blocks the axial spaced orifices 51 so as to cause the escape path of fluid from the variable volume chamber to be progressively restricted.
• a counteracting force is developed within the chamber which is effective in decelerating the movement of the piston means 12 in the last stages of the retracting stroke for stopping the piston means in a smooth controlled manner so as to

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Actuator (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (3)

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Citations (7)

• 1978
  • 1978-11-20 GB GB8016178A patent/GB2049051B/en not_active Expired
  • 1978-11-20 WO PCT/US1978/000169 patent/WO1980001097A1/en not_active Ceased
  • 1978-11-20 JP JP50123778A patent/JPS55500916A/ja active Pending

Patent Citations (7)

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