US3896707A - Filled piston retaining means with erosion protection - Google Patents

Filled piston retaining means with erosion protection Download PDF

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Publication number
US3896707A
US3896707A US391337A US39133773A US3896707A US 3896707 A US3896707 A US 3896707A US 391337 A US391337 A US 391337A US 39133773 A US39133773 A US 39133773A US 3896707 A US3896707 A US 3896707A
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US
United States
Prior art keywords
core
piston
retaining means
cavity
filler material
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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 - Lifetime
Application number
US391337A
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English (en)
Inventor
William L Holmstrom
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.)
Caterpillar Inc
Original Assignee
Caterpillar Tractor Co
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Filing date
Publication date
Application filed by Caterpillar Tractor Co filed Critical Caterpillar Tractor Co
Priority to US391337A priority Critical patent/US3896707A/en
Priority to GB3642474A priority patent/GB1457460A/en
Priority to JP49097478A priority patent/JPS5848750B2/ja
Application granted granted Critical
Publication of US3896707A publication Critical patent/US3896707A/en
Assigned to CATERPILLAR INC., A CORP. OF DE. reassignment CATERPILLAR INC., A CORP. OF DE. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: CATERPILLAR TRACTOR CO., A CORP. OF CALIF.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J1/00—Pistons; Trunk pistons; Plungers
    • F16J1/005—Pistons; Trunk pistons; Plungers obtained by assembling several pieces
    • F16J1/006—Pistons; Trunk pistons; Plungers obtained by assembling several pieces of different materials
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/122—Details or component parts, e.g. valves, sealings or lubrication means
    • F04B1/124—Pistons

Definitions

  • ABSTRACT A piston such as used in axial piston hydraulic translating units, comprising a hollowed-out skirt portion defining a cavity filled with a core of lightweight filler material, the material being retained in place against axial displacement by convex disc core-retaining means forceably insertable within said cavity. In position, the core-retaining means further protects the core filler material from erosion due to high ambient fluid pressure.
  • This invention relates to a reciprocating piston-type fluid translating device such as used for pumps or motors. More specifically, the invention relates to a lightweight core piston of the type used in these units having an improved means for retaining the core against axial displacement during operation of the piston, and for protecting the core material from erosion due to fluid pressure.
  • the weight of the pistons contained within these translating units is reduced by hollowing out the skirt portion of the pistons.
  • This increases the dead volume of fluid that must be moved within the translating unit, and can have the effect of decreasing the efficiency of these units. Consequently. it is usual to refill the hollowedout portion with a material of lighter weight than that of the piston, and which possesses a sufficiently high bulk modulus to resist compression under the high pressures encountered during operation.
  • Such filler material must be positively retained within the piston in some manner, so that it will not be displaced during operation of the translating units, thereby potentially causing severe damage to such units.
  • the core retaining means of this invention provides a relatively simple and economical method of retaining a lightweight core of filler material within the bore of a piston, while at the same time protecting this filler material from erosion resulting from exposure to fluid pressure.
  • FIG. 1 is a partially cut-away longitudinal crosssectional elevation of an axial piston hydraulic translating unit including a piston embodying the core-retaining means of this invention
  • FIG. 2 is a cross-sectional elevation of the piston of FIG. 1 illustrating the core filler material in conjunction with the core-retaining means of this invention.
  • FIG. 3 is a fragmented cross-sectional elevation of a piston illustrating an alternate embodiment of the coreretaining means of this invention.
  • FIGS. 1, 2 and 3 illustrate pistons useful in pistontype hydraulic translating units.
  • axial piston hydraulic pump or motor 10 hereinafter referred to as pump 10
  • pump 10 having rotatable drive shaft 11 extending through end wall 12 of cylindrical housing 13.
  • Circular head 14 closes end of housing 13 opposite from end wall 12, and a pair of bearings 16 support drive shaft 11 in end wall 12., and head 14, respectively.
  • annular barrel I8 is disposed in coaxial relationship to drive shaft 11, and has sleeve portion 19 extending towards end wall 12 and carrying first splines 20 which engage second splines 21 on drive shaft 11, so that barrel 18 and drive shaft 11 are con strained to rotate together.
  • Barrel 18 is provided with a plurality of cylindrical bores 22 (one shown) which extend in a direction parallel to drive shaft 11, and are in equally angularly spaced relationship thereto.
  • a cylindrical hollow-filled core piston 23 is disposed in each bore 22.
  • Each piston 23 is provided with a ball element forming a spherical base portion 24 thereof.
  • Piston 23 is further provided with core-retaining means 25 in the trailing end portion thereof.
  • a cam plate 30 is disposed within chamber 17 against end wall 12, having a flat surface 26 angled relative to the rotary axis of drive shaft 11 and barrel 18.
  • Spherical base portion 24 of piston 23 is received in conforming depression 27 of slipper pad 28 which rides against flat surface 26 of cam plate 30.
  • a circular port plate 29 is disposed between barrel 18 and head 14; a first passage 31 extends from bore 22 through port plate 29.
  • Port plate 29 is provided with a pair of arcuate slots 32 (one shown) having a radius equal to the spacing of first passage 31 from the rotary axis.
  • Head 14 has conventionally arranged inlet and outlet ports (not shown) formed therein which open to slots 32.
  • piston 23 In operation, rotation of drive shaft 11 rotates barrel 18, and piston 23 is reciprocated in bore 22 by cam plate 30. As barrel 18 rotates, piston 23 delivers high pressure fluid through first passage 31 as it passes over the outlet port and port plate 29, and receives inlet fluid through the inlet port as it passes over the inlet port, in a conventional manner.
  • piston 23 comprising generally spherical base portion 24 and hollow skirt portion 33 is shown filled with lightweight core filler material 34.
  • This core filler material may be any suitable lightweight material such as that described in the co-pending application of Bristow, et al., Ser. No. 371,666, Filed June 20, 1973, having the same assignee as the present invention.
  • inner wall 3 of hollow skirt portion 33 defines a stepped cavity 37 (shown filled with filler material 34 of a cured epoxy resin, or the like.
  • the cross-section of the cavity is substantially smaller at the end proximate to spherical base portion 24, and substantially larger proximate trailing end 38.
  • the wall connecting the two portions of the cavity may be angled to relieve stresses and suitably accommodate the lightweight filler.
  • Filler material 34 is held against axial displacement and protected from erosion due to fluid pressure by coreretaining means 25, generally comprising a concavo-convex circular dial having an inwardly converging outer periphery 39.
  • coreretaining means 25 generally comprising a concavo-convex circular dial having an inwardly converging outer periphery 39.
  • a protrusion 41 is provided in core filler material 34, for example by machining, and coreretaining means 25 is forceably inserted into trailing end 38 of piston 23 and abuts the protrusion 41.
  • core retaining means 25 provides point contact circumferentially around inner wall 36 of hollow skirt portion 33.
  • the forces exerted by core-retaining means 25 against inner wall 36 and filler material 34 retains both coreretaining means 25 and filler material 34 in position.
  • Core-retaining means 25 may be of any suitable material having sufficient durability to protect filler material 34 from erosion, and sufficient flexibility to permit insertion.
  • a resilient steel is excellent for this purpose.
  • Axial second passage 42 through core filler material 34 communicating with third passage 43 in spherical base portion 24 is provided as a channel for the flow of lubricant through piston 23.
  • a hole 44 in core-retaining means 25 is provided to permit lubricant to enter second and third passages 42 and 43.
  • second passage 42 is formed by placing a long rod extending the length of the piston 23 into third passage 43 prior to filling cavity 37, as described in the copending application of Hein, et al., Ser. No. 115,639, filed Feb. 16, 1971, now US. Pat. No. 3,707,l 13 having the same assignee as the present invention.
  • the core filler material 34 is then molded around the rod in the cavity 37, leaving a passage when the rod is removed.
  • the passage may be drilled through the filler material after it has hardened.
  • FIG. 3 an alternate embodiment of core-retaining means 25 having an outwardlyconverging outer periphery 45 is shown in position against filler material 34 in piston 23.
  • a piston of the type used in hydraulic translating units wherein said piston has a base portion for engaging said piston to said unit, and an attached skirt portion with a trailing end, said piston defining a hollowed out cavity extending axially from a plane rearward of said base to an opening in the trailing end, and a core of filler material within said cavity and essentially filling the same; means for retaining the core of filler material within said cavity including concavo-convex disc coreretaining means press-fitted within said cavity, said disc core-retaining means having a press-fit outer edge surface defining an acute angle with respect to said cavity, and said disc core-retaining means having its concave face in contact with an annular protrusion on an end portion of said core filler material positioned within said cavity.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Reciprocating Pumps (AREA)
  • Details Of Reciprocating Pumps (AREA)
  • Hydraulic Motors (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)
  • Soil Working Implements (AREA)
US391337A 1973-08-24 1973-08-24 Filled piston retaining means with erosion protection Expired - Lifetime US3896707A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US391337A US3896707A (en) 1973-08-24 1973-08-24 Filled piston retaining means with erosion protection
GB3642474A GB1457460A (en) 1973-08-24 1974-08-19 Pistons
JP49097478A JPS5848750B2 (ja) 1973-08-24 1974-08-24 液圧伝達ユニットに使用するピストン

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US391337A US3896707A (en) 1973-08-24 1973-08-24 Filled piston retaining means with erosion protection

Publications (1)

Publication Number Publication Date
US3896707A true US3896707A (en) 1975-07-29

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ID=23546200

Family Applications (1)

Application Number Title Priority Date Filing Date
US391337A Expired - Lifetime US3896707A (en) 1973-08-24 1973-08-24 Filled piston retaining means with erosion protection

Country Status (3)

Country Link
US (1) US3896707A (OSRAM)
JP (1) JPS5848750B2 (OSRAM)
GB (1) GB1457460A (OSRAM)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4191095A (en) * 1976-11-26 1980-03-04 Linde Ag Hollow piston for hydrostatic machines
EP0396898A1 (de) * 1989-04-13 1990-11-14 Hydromatik GmbH Kolben für Kolbenmaschinen
US5072655A (en) * 1988-02-12 1991-12-17 Hydromatik Gmbh Pistons for axial piston machines
US6250206B1 (en) 1999-02-10 2001-06-26 Sauer-Danfoss Inc. Hydraulic piston filling
US6293185B1 (en) 2000-02-28 2001-09-25 Sauer-Danfoss Inc. Piston for a hydrostatic cylinder block
US6314864B1 (en) 2000-07-20 2001-11-13 Sauer-Danfoss Inc. Closed cavity piston for hydrostatic units
US6318242B1 (en) 1999-10-26 2001-11-20 Sauer-Danfoss Inc. Filled hydraulic piston and method of making the same
US6338293B1 (en) 2000-06-30 2002-01-15 Sauer-Danfoss Inc. Reduced oil volume piston assembly for a hydrostatic unit
US6422130B1 (en) * 1999-06-04 2002-07-23 Valeo Piston and hydraulic control device for the clutch of an automobile provided with one such piston
US6431051B1 (en) 2000-03-31 2002-08-13 Sauer-Danfoss Inc. Closed cavity hydraulic piston and method of making the same
US6491206B2 (en) 2000-11-27 2002-12-10 Sauer-Danfoss, Inc. Method of making closed cavity pistons
US20090272260A1 (en) * 2008-05-05 2009-11-05 Alejandro Moreno Pressure attenuated pump piston
CN102818018A (zh) * 2012-08-03 2012-12-12 烟台艾迪精密机械股份有限公司 一种冲击活塞及采用该冲击活塞的液压破碎锤
WO2013082379A1 (en) * 2011-12-01 2013-06-06 Caterpillar Inc. Piston assembly for a fluid translating device
US9915248B2 (en) 2009-12-03 2018-03-13 Danfoss A/S Hydraulic piston machine, in particular water hydraulic machine
CN110043421A (zh) * 2016-03-18 2019-07-23 朱日明 液压装置用柱塞及液压装置

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5884453U (ja) * 1982-07-19 1983-06-08 三菱マテリアル株式会社 圧縮機の超硬プランジヤ
JPS59113558U (ja) * 1983-01-24 1984-07-31 イズミ工業株式会社 ピストンピン

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1167975A (en) * 1914-05-21 1916-01-11 Engineering Products Corp Pneumatic-tool piston.
US1881945A (en) * 1929-08-26 1932-10-11 Alemite Corp Centralized lubricating system
US2541250A (en) * 1947-06-19 1951-02-13 Girling Ltd Fluid-tight closure for a cylinder or other container
US3000304A (en) * 1955-09-30 1961-09-19 T W Hand Fireworks Co Ltd Container closure
US3325891A (en) * 1964-09-29 1967-06-20 Westinghouse Air Brake Co Method of closing core pin holes
US3633467A (en) * 1968-12-28 1972-01-11 Komatsu Mfg Co Ltd Hydraulic pump or motor device plungers
US3741077A (en) * 1972-04-24 1973-06-26 Eaton Corp Piston assembly

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1167975A (en) * 1914-05-21 1916-01-11 Engineering Products Corp Pneumatic-tool piston.
US1881945A (en) * 1929-08-26 1932-10-11 Alemite Corp Centralized lubricating system
US2541250A (en) * 1947-06-19 1951-02-13 Girling Ltd Fluid-tight closure for a cylinder or other container
US3000304A (en) * 1955-09-30 1961-09-19 T W Hand Fireworks Co Ltd Container closure
US3325891A (en) * 1964-09-29 1967-06-20 Westinghouse Air Brake Co Method of closing core pin holes
US3633467A (en) * 1968-12-28 1972-01-11 Komatsu Mfg Co Ltd Hydraulic pump or motor device plungers
US3741077A (en) * 1972-04-24 1973-06-26 Eaton Corp Piston assembly

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4191095A (en) * 1976-11-26 1980-03-04 Linde Ag Hollow piston for hydrostatic machines
US5072655A (en) * 1988-02-12 1991-12-17 Hydromatik Gmbh Pistons for axial piston machines
EP0396898A1 (de) * 1989-04-13 1990-11-14 Hydromatik GmbH Kolben für Kolbenmaschinen
US5007332A (en) * 1989-04-13 1991-04-16 Hydromatik Gmbh Piston for piston machines
US6250206B1 (en) 1999-02-10 2001-06-26 Sauer-Danfoss Inc. Hydraulic piston filling
US6422130B1 (en) * 1999-06-04 2002-07-23 Valeo Piston and hydraulic control device for the clutch of an automobile provided with one such piston
US6318242B1 (en) 1999-10-26 2001-11-20 Sauer-Danfoss Inc. Filled hydraulic piston and method of making the same
US6318241B1 (en) 2000-02-28 2001-11-20 Sauer-Danfoss Inc. Piston for a hydrostatic cylinder block
US6293185B1 (en) 2000-02-28 2001-09-25 Sauer-Danfoss Inc. Piston for a hydrostatic cylinder block
US6431051B1 (en) 2000-03-31 2002-08-13 Sauer-Danfoss Inc. Closed cavity hydraulic piston and method of making the same
US6338293B1 (en) 2000-06-30 2002-01-15 Sauer-Danfoss Inc. Reduced oil volume piston assembly for a hydrostatic unit
US6314864B1 (en) 2000-07-20 2001-11-13 Sauer-Danfoss Inc. Closed cavity piston for hydrostatic units
US6491206B2 (en) 2000-11-27 2002-12-10 Sauer-Danfoss, Inc. Method of making closed cavity pistons
US20090272260A1 (en) * 2008-05-05 2009-11-05 Alejandro Moreno Pressure attenuated pump piston
US7938059B2 (en) * 2008-05-05 2011-05-10 Delphi Technologies, Inc. Pressure attenuated pump piston
US9915248B2 (en) 2009-12-03 2018-03-13 Danfoss A/S Hydraulic piston machine, in particular water hydraulic machine
WO2013082379A1 (en) * 2011-12-01 2013-06-06 Caterpillar Inc. Piston assembly for a fluid translating device
CN102818018A (zh) * 2012-08-03 2012-12-12 烟台艾迪精密机械股份有限公司 一种冲击活塞及采用该冲击活塞的液压破碎锤
CN110043421A (zh) * 2016-03-18 2019-07-23 朱日明 液压装置用柱塞及液压装置

Also Published As

Publication number Publication date
JPS5848750B2 (ja) 1983-10-31
JPS5050701A (OSRAM) 1975-05-07
GB1457460A (en) 1976-12-01

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Legal Events

Date Code Title Description
AS Assignment

Owner name: CATERPILLAR INC., 100 N.E. ADAMS STREET, PEORIA, I

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:CATERPILLAR TRACTOR CO., A CORP. OF CALIF.;REEL/FRAME:004669/0905

Effective date: 19860515

Owner name: CATERPILLAR INC., A CORP. OF DE.,ILLINOIS

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CATERPILLAR TRACTOR CO., A CORP. OF CALIF.;REEL/FRAME:004669/0905

Effective date: 19860515