GB2347193A - A vibration reducing piston - Google Patents

A vibration reducing piston Download PDF

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Publication number
GB2347193A
GB2347193A GB9903962A GB9903962A GB2347193A GB 2347193 A GB2347193 A GB 2347193A GB 9903962 A GB9903962 A GB 9903962A GB 9903962 A GB9903962 A GB 9903962A GB 2347193 A GB2347193 A GB 2347193A
Authority
GB
United Kingdom
Prior art keywords
piston
layer
crown portion
skirt portion
cylinder
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Withdrawn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
GB9903962A
Other versions
GB9903962D0 (en
Inventor
David Thornton Pindar
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.)
Federal Mogul Technology Ltd
Original Assignee
Federal Mogul Technology 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 Federal Mogul Technology Ltd filed Critical Federal Mogul Technology Ltd
Priority to GB9903962A priority Critical patent/GB2347193A/en
Publication of GB9903962D0 publication Critical patent/GB9903962D0/en
Priority to PCT/GB2000/000396 priority patent/WO2000050758A1/en
Publication of GB2347193A publication Critical patent/GB2347193A/en
Withdrawn legal-status Critical Current

Links

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
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J1/00—Pistons; Trunk pistons; Plungers
    • F16J1/04—Resilient guiding parts, e.g. skirts, particularly for trunk pistons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 
    • F02F3/10—Pistons  having surface coverings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F7/00—Casings, e.g. crankcases or frames
    • F02F7/0065—Shape of casings for other machine parts and purposes, e.g. utilisation purposes, safety
    • F02F7/008—Sound insulation
    • 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
    • F16J1/08—Constructional features providing for lubrication
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2201/00—Metals
    • F05C2201/02—Light metals
    • F05C2201/021—Aluminium

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)

Abstract

A piston 10 for an internal combustion engine comprises a crown portion 12 and a skirt portion 14. The piston 10 also had a layer 22 of resilient material adhered to at least part of or at least one of the lower surface of the crown 12 and the inner surface of the skirt 14. At the resonant frequency of the piston 10, the piston 10 has ante-nodes and the layer 22 extends across them. The layer 22 may be 1 to 2 mm of silicon rubber and have gaps which allow cooling oil to reach the surfaces of the piston 10. The layer 22 helps reduce vibrations which in turn reduces wear.

Description

PISTON This invention is concerned with a piston, in particular, a piston for an internal combustion engine.
A conventional piston for an internal combustion engine comprises a crown portion having an upper surface designed to extend across a cylinder in which the piston reciprocates. The upper surface of the crown portion is presented to a combustion chamber of the engine. The crown portion also has a side surface which defines piston ring grooves which house piston rings for sealing the gap between the piston and the cylinder. The crown portion also has a lower surface which, in most pistons, extends generally parallel to the upper surface of the crown portion.
In addition to the crown portion thereof, a conventional piston for an internal combustion engine comprises a skirt portion having an outer surface designed to guide the piston in the cylinder in which the piston reciprocates, and an inner surface which at least partially encloses a space below the lower surface of said crown portion. In most cases, the skirt portion is integral with the crown portion and depends therefrom, the outer surface of the skirt portion being continuous with the side surface of the crown portion and the inner surface of the skirt portion meeting the lower surface of the crown portion. In some pistons, however, the skirt portion is pivotally connected to the crown portion.
A conventional piston for an internal combustion engine also comprises one or two bosses on which a gudgeon pin is supported to connect the piston to a connecting rod.
The boss or bosses sometimes depend from the lower surface of the crown portion but, in some cases, are supported additionally or instead by the skirt portion. In pistons in which the skirt portion is pivotally connected to the crown portion, a pin passes through a boss which is integral with the crown portion and also through a boss which is integral with the skirt portion.
The pistons of an internal combustion engine reciprocate in their cylinders at high speed and are subject to shocks caused by combustion in the combustion chamber above the upper surface of the crown portion of the piston and shocks caused by impacts with the side wall of the cylinder. Such shocks can cause the piston or part thereof to vibrate, eg at the piston's natural resonance frequency. Such vibration can result in undesirable noise, and/or greater wear between the piston and the cylinder.
It is an object of the present invention to provide a piston for an internal combustion engine having a reduced tendency to vibrate.
The invention provides a piston suitable for use in an internal combustion engine, the piston comprising a crown portion having an upper surface designed to extend across a cylinder in which the piston reciprocates, a side surface defining piston ring grooves, and a lower surface, the piston also comprising a skirt portion having an outer surface designed to guide the piston in the cylinder in which the piston reciprocates, and an inner surface which at least partially encloses a space below the lower surface of said crown portion, wherein the piston also comprises a layer of resilient material adhered to at least part of at least one of said lower surface of the crown portion and said inner surface of the skirt portion.
In a piston according to the invention, the layer of resilient material serves to damp vibrations of the piston.
Preferably, said layer extends across the or each of the anti-nodes of the resonance frequency of the piston, thereby ensuring efficient damping.
In order to allow for the piston to be cooled, in the conventional manner, by oil thrown up from the sump of the engine, said layer, preferably, has gaps therein to allow cooling oil to reach the surface or surfaces to which the layer is adhered.
Said layer may comprise silicon rubber, or any other suitable resilient material which can withstand the temperatures attained, in service, by the region of the piston to which the layer adheres. Preferably, the material of the layer is selected from materials which adhere naturally to the metal of the piston but, if necessary, a separate adhesive can be used. Said layer may have a thickness of 1 to 2mm, the optimum thickness for damping being three times the thickness of the substrate but for cost and weight reduction reasons the layer preferably has a lower thickness than said optimum.
There now follows a detailed description, to be read with reference to the accompanying drawings, of a piston which is illustrative of the invention.
In the drawings: Figure 1 is a perspective view, with parts broken away, of the illustrative piston; and Figure 2 is a half cross-section taken vertically through the illustrative piston.
The illustrative piston 10 is suitable for use in an internal combustion engine. The piston 10 comprises a crown portion 12, a skirt portion 14, and a boss portion 16 (omitted from Figure 1). The portions 12,14 and 16 are an integral casting of aluminium alloy.
The crown portion 12 has an upper surface 12a which is designed to extend across a cylinder (not shown) in which the piston 10 reciprocates. The surface 12a is generally flat and has a slightly oval outer periphery. The crown portion 12 also has a side surface 12b which extends at right angles to the upper surface 12a, meeting the outer periphery of the surface 12a. The surface 12b extends around the crown portion 12 and defines two piston ring grooves 12c. The crown portion 12 also has a lower surface 12d which is parallel to the upper surface 12a. The lower surface 12d is generally annular as it encircles the boss portion 16.
The skirt portion 14 is generally in the form of a hollow cylinder depending from the outer periphery of the lower surface 12d of the crown portion 12. The skirt portion 14 has an outer surface 14a which is continuous with the surface 12b and is designed to guide the piston 10 in the cylinder in which the piston reciprocates. The skirt portion 14 also has an inner surface 14b which encloses a space below the lower surface 12d of the crown portion 12, except that two circular holes 18 pass through the skirt portion 14 at diametrically-opposed points thereon.
The boss portion 16 depends from the centre of the lower surface 12d of the crown portion 12. The boss portion 16 define a horizontally-extending cylindrical bore 20 which is axially with the holes 18. The bore 20 is designed to receive a gudgeon pin (not shown) which connects the piston 10 to a connecting rod (not shown).
The holes 18 allow access for the gudgeon pin.
The piston 10 also comprises a layer 22 of resilient material, specifically silicon rubber. The layer 22 is lmm in thickness and is adhered to the lower surface 12d of the crown portion 12 and is also adhered to the inner surface 14b of the skirt portion 14. Except for a regular pattern of gaps 24 therein, the layer 22 covers all of the surfaces 12d and 14b. The gaps 24 are in a regular pattern and are generally rectangular with their longer dimension extending generally circumferentially of the piston 10. The gaps 24 allow cooling oil to reach the surfaces 12d and 14b to which the layer 22 is adhered.
The layer 22 is found to effectively damp vibrations of the piston 10 since it extends across anti-nodes of the resonance frequency of the piston 10, these anti-nodes extending circumferentially around the skirt portion 14.

Claims (6)

  1. CLAIMS 1 A piston suitable for use in an internal combustion engine, the piston comprising a crown portion having an upper surface designed to extend across a cylinder in which the piston reciprocates, a side surface defining piston ring grooves, and a lower surface, the piston also comprising a skirt portion having an outer surface designed to guide the piston in the cylinder in which the piston reciprocates, and an inner surface which at least partially encloses a space below the lower surface of said crown portion, wherein the piston also comprises a layer of resilient material adhered to at least part of at least one of said lower surface of the crown portion and said inner surface of the skirt portion.
  2. 2 A piston according to claim 1, wherein said layer extends across the or each of the anti-nodes of the resonance frequency of the piston.
  3. 3 A piston according to either one of claims 1 and 2, wherein said layer has gaps therein to allow cooling oil to reach the surface or surfaces to which the layer is adhered.
  4. 4 A piston according to any one of claims 1 to 3, wherein said layer comprises silicon rubber.
  5. 5 A piston according to any one of claims 1 to 4, wherein said layer has a thickness of 1 to 2mm.
  6. 6 A piston substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.
GB9903962A 1999-02-23 1999-02-23 A vibration reducing piston Withdrawn GB2347193A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB9903962A GB2347193A (en) 1999-02-23 1999-02-23 A vibration reducing piston
PCT/GB2000/000396 WO2000050758A1 (en) 1999-02-23 2000-02-10 Piston

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9903962A GB2347193A (en) 1999-02-23 1999-02-23 A vibration reducing piston

Publications (2)

Publication Number Publication Date
GB9903962D0 GB9903962D0 (en) 1999-04-14
GB2347193A true GB2347193A (en) 2000-08-30

Family

ID=10848209

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9903962A Withdrawn GB2347193A (en) 1999-02-23 1999-02-23 A vibration reducing piston

Country Status (2)

Country Link
GB (1) GB2347193A (en)
WO (1) WO2000050758A1 (en)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5063894A (en) * 1989-11-11 1991-11-12 Kolbenschmidt Aktiengesellschaft Pressure-diecast light-alloy piston for internal combustion engines

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3995538A (en) * 1975-05-30 1976-12-07 General Motors Corporation Crosshead piston assembly
US4470375A (en) * 1983-06-09 1984-09-11 Automotive Engine Associates Fully hydrodynamic piston ring and piston assembly with elastomerically conforming geometry and internal cooling
JPH0921347A (en) * 1995-07-06 1997-01-21 Isuzu Ceramics Kenkyusho:Kk Structure for thermal insulation type engine provided with thermal insulation layer and sound absorbing layer

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5063894A (en) * 1989-11-11 1991-11-12 Kolbenschmidt Aktiengesellschaft Pressure-diecast light-alloy piston for internal combustion engines

Also Published As

Publication number Publication date
GB9903962D0 (en) 1999-04-14
WO2000050758A1 (en) 2000-08-31

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Legal Events

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