GB2182270A - The manufacture of pistons - Google Patents

The manufacture of pistons Download PDF

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Publication number
GB2182270A
GB2182270A GB08626314A GB8626314A GB2182270A GB 2182270 A GB2182270 A GB 2182270A GB 08626314 A GB08626314 A GB 08626314A GB 8626314 A GB8626314 A GB 8626314A GB 2182270 A GB2182270 A GB 2182270A
Authority
GB
United Kingdom
Prior art keywords
piston
axis
skirt
bearing surfaces
spaced
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.)
Granted
Application number
GB08626314A
Other versions
GB8626314D0 (en
GB2182270B (en
Inventor
John Gowen Collyear
David Alex Parker
Michael Ledsham Price Rhodes
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.)
AE PLC
Original Assignee
AE PLC
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
Priority claimed from GB838323843A external-priority patent/GB8323843D0/en
Application filed by AE PLC filed Critical AE PLC
Publication of GB8626314D0 publication Critical patent/GB8626314D0/en
Publication of GB2182270A publication Critical patent/GB2182270A/en
Application granted granted Critical
Publication of GB2182270B publication Critical patent/GB2182270B/en
Expired 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
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J1/00—Pistons; Trunk pistons; Plungers
    • F16J1/02—Bearing surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
    • B23P15/003—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass bearings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
    • B23P15/10—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass 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 

Abstract

A piston is manufactured by having formed cylindrical portions 35a, 35b which are alternatively offset to one side or other of the piston axis to form, on each side of the piston, alternate projecting bearing surfaces 37 and recessed skirt portions 38. The piston is formed by machining a piston blank alternately about one or other of two axes which are parallel to the piston axis but which are spaced on opposite sides of the piston axis. <IMAGE>

Description

SPECIFICATION The manufacture of pistons The invention relates to the manufacture of pistons having a skirt on which are formed a plurality of bearing surfaces for transmitting lateral th rust from the piston to an associated cylinder or liner, each bearing surface being at a predetermined axial position on the skirt, being spaced outwardly of the skirt to are quired radial dimension and extending around the skirt with a required circumferential dimension, hereinaftercalled "a piston of the kind referred to".
It has recently been discovered that improved lubrication and reduced friction between the piston and an associated cylinder or liner can be achieved by replacing the conventional generally cylindrical skirt with such individual bearing surfaces. The bearing surfaces are provided on both the thrust side and the counter-thrust side ofthe piston, which lie on opposite sides ofthe plane including the piston axis and the axis of a gudgeon pin bore of the piston. Two or more bearing surfaces are provided on each side and can be arranged in various configurations to give optimum performance. The bearing surfaces extending radially outwardly of the surrounding skirt portion by, in general,; as little as 25 microns and areconnec- ted to the surrounding skirtbysloping ramps.In addition, the circumferential extent of each bearing surface is, in general, 15 or 20".
Itwill be appreciatedthatthesmall distance by which the bearing surfaces are spaced outwardly of the surrounding skirt and the limited circumferential extent of the bearing surfaces make the manufacture of such a piston more difficult than the manufacture of conventional pistons, which can be made by a conventional turning operation using conventional machine tools. In general, such machine tools do not, however, have sufficient flexibility to machine pistons ofthe kind referred to above at commercial rates of production.
According to a first aspect ofthe invention, there is provided a method of manufacturing a piston ofthe kind referred to comprising machining a piston blank alternately about one or other of two axes which are parallel to the piston axis but which are spaced on opposite sides of the piston axis, to form a succession of radially staggered generally cylindrical portions each of which, relative to the adjacent portions, projects to one side ofthe piston and is recessed to the other side of the piston, the projections forming the bearing surfaces and the recesses forming the skirt.
According to a second aspect of the invention, there is provided a piston for an internal combustion engine of the kind referred to formed below the ring band with two sets of generally cylindrical portions with one set of said cylindrical portions having a common axis parallel to but spaced from the piston axis and a second set of said cylindrical portions alternating with said one set and having a common axis parallel to but spaced from the piston axis on the opposite side of the piston axis from the axis of said one set, the two sets forming a succession of radially staggered generally cylindrical portions each of which, relative to the adjacent portions projects to one side of the piston and is recessed to the other side of the piston, the projections forming bearing surfaces forthe transmission of lateral thrust from the piston to an associated cylinder or liner, and the recesses forming a skirt.
The following is a more detailed description of some embodiments of the invention, by way of ex ample, reference being made to the accompanying drawing which is an elevation and section of a piston foran internal combustion engine showing four bearing surfaces.
The piston comprises a crown and surrounding ring band (notshown). Below the ring band, the piston is formed with two sets of generally cylindrical portions 35a, 35b. One set of portions 35a has a common axis 36a parallel to but spaced from the piston axis 16. The second set of such portions 35b also have a common axis 36b parallel to but spaced from the piston axis 16 but on the opposite side ofthe piston axis 16 to the first axis 36a. In this way, there are formed a succession of radially staggered generally cylindrical portions 35a, 35b each of which, relat ive to the adjacent portions projects to one side ofthe piston and is recessed to the other side of the piston.
The projections form bearing surfaces 37 and there- cessesform a skirt 38.
It will be appreciated that the offsets are exaggerated in the drawing for the sake of clarity. In practice, the offsets may be of the order of only a few microns, for example 35 microns or up to 125 microns.
The piston is manufactured as follows. A generally cylindrical piston blank is machined alternately about one or other of two axes 36a, 36b which are parallel to the piston axis 16 but which are spaced on opposite sides of the piston axis 16. The tool 30 travels in a circular path and is stepped from one axis to the other after predetermined amounts of axial travel.
1. A method of manufacturing a piston of the kind referred to, comprising machining a piston blank alternately about one or other of two axes which are parallel to the piston axis but which are spaced on opposite sides of the piston axis, to form a succession of radially staggered generally cylindrical portions each of which, relative to the adjacent portions, projects to one side of the piston and is recessed to the other side of the piston,the projections forming the bearing surfaces and the recesses forming the skirt.
2. A method of manufacturing a piston of the kind referred to, substantially as hereinbefore described with reference to the accompanying drawing.
3. A piston when made by the method of claim 1 or claim 2.
4. A piston for an internal combustion engine of the kind referred to, formed belowthe ring band with two sets of generally cylindrical portions, one set of said cylindrical portions having a common axis parallel to but spaced from the piston axis and a second set of said cylindrical portions alternating with said one set and having a common axis parallel to but
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION The manufacture of pistons The invention relates to the manufacture of pistons having a skirt on which are formed a plurality of bearing surfaces for transmitting lateral th rust from the piston to an associated cylinder or liner, each bearing surface being at a predetermined axial position on the skirt, being spaced outwardly of the skirt to are quired radial dimension and extending around the skirt with a required circumferential dimension, hereinaftercalled "a piston of the kind referred to". It has recently been discovered that improved lubrication and reduced friction between the piston and an associated cylinder or liner can be achieved by replacing the conventional generally cylindrical skirt with such individual bearing surfaces. The bearing surfaces are provided on both the thrust side and the counter-thrust side ofthe piston, which lie on opposite sides ofthe plane including the piston axis and the axis of a gudgeon pin bore of the piston. Two or more bearing surfaces are provided on each side and can be arranged in various configurations to give optimum performance. The bearing surfaces extending radially outwardly of the surrounding skirt portion by, in general,; as little as 25 microns and areconnec- ted to the surrounding skirtbysloping ramps.In addition, the circumferential extent of each bearing surface is, in general, 15 or 20". Itwill be appreciatedthatthesmall distance by which the bearing surfaces are spaced outwardly of the surrounding skirt and the limited circumferential extent of the bearing surfaces make the manufacture of such a piston more difficult than the manufacture of conventional pistons, which can be made by a conventional turning operation using conventional machine tools. In general, such machine tools do not, however, have sufficient flexibility to machine pistons ofthe kind referred to above at commercial rates of production. According to a first aspect ofthe invention, there is provided a method of manufacturing a piston ofthe kind referred to comprising machining a piston blank alternately about one or other of two axes which are parallel to the piston axis but which are spaced on opposite sides of the piston axis, to form a succession of radially staggered generally cylindrical portions each of which, relative to the adjacent portions, projects to one side ofthe piston and is recessed to the other side of the piston, the projections forming the bearing surfaces and the recesses forming the skirt. According to a second aspect of the invention, there is provided a piston for an internal combustion engine of the kind referred to formed below the ring band with two sets of generally cylindrical portions with one set of said cylindrical portions having a common axis parallel to but spaced from the piston axis and a second set of said cylindrical portions alternating with said one set and having a common axis parallel to but spaced from the piston axis on the opposite side of the piston axis from the axis of said one set, the two sets forming a succession of radially staggered generally cylindrical portions each of which, relative to the adjacent portions projects to one side of the piston and is recessed to the other side of the piston, the projections forming bearing surfaces forthe transmission of lateral thrust from the piston to an associated cylinder or liner, and the recesses forming a skirt. The following is a more detailed description of some embodiments of the invention, by way of ex ample, reference being made to the accompanying drawing which is an elevation and section of a piston foran internal combustion engine showing four bearing surfaces. The piston comprises a crown and surrounding ring band (notshown). Below the ring band, the piston is formed with two sets of generally cylindrical portions 35a, 35b. One set of portions 35a has a common axis 36a parallel to but spaced from the piston axis 16. The second set of such portions 35b also have a common axis 36b parallel to but spaced from the piston axis 16 but on the opposite side ofthe piston axis 16 to the first axis 36a. In this way, there are formed a succession of radially staggered generally cylindrical portions 35a, 35b each of which, relat ive to the adjacent portions projects to one side ofthe piston and is recessed to the other side of the piston. The projections form bearing surfaces 37 and there- cessesform a skirt 38. It will be appreciated that the offsets are exaggerated in the drawing for the sake of clarity. In practice, the offsets may be of the order of only a few microns, for example 35 microns or up to 125 microns. The piston is manufactured as follows. A generally cylindrical piston blank is machined alternately about one or other of two axes 36a, 36b which are parallel to the piston axis 16 but which are spaced on opposite sides of the piston axis 16. The tool 30 travels in a circular path and is stepped from one axis to the other after predetermined amounts of axial travel. CLAIMS
1. A method of manufacturing a piston of the kind referred to, comprising machining a piston blank alternately about one or other of two axes which are parallel to the piston axis but which are spaced on opposite sides of the piston axis, to form a succession of radially staggered generally cylindrical portions each of which, relative to the adjacent portions, projects to one side of the piston and is recessed to the other side of the piston,the projections forming the bearing surfaces and the recesses forming the skirt.
2. A method of manufacturing a piston of the kind referred to, substantially as hereinbefore described with reference to the accompanying drawing.
3. A piston when made by the method of claim 1 or claim 2.
4. A piston for an internal combustion engine of the kind referred to, formed belowthe ring band with two sets of generally cylindrical portions, one set of said cylindrical portions having a common axis parallel to but spaced from the piston axis and a second set of said cylindrical portions alternating with said one set and having a common axis parallel to but spaced from the piston axis on the opposite side of the piston axis from the axis of said one set, the two sets forming a succession of radially staggered generally cylindrical portions each of which, relative to the adjacent portions projects to one side of the piston and is recessed to the other side of the piston, the projections forming bearing surfacesforthetrans- mission of lateral thrust from the piston to an associated cylinder or liner and the recesses forming a skirt.
5. A piston for an internal combustion engine substantially as hereinbefore described with refer ence to the accompanying drawing.
GB08626314A 1983-09-06 1984-08-24 The manufacture of pistons Expired GB2182270B (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB838323843A GB8323843D0 (en) 1983-09-06 1983-09-06 Pistons
GB08421569A GB2145945B (en) 1983-09-06 1984-08-24 The manufacture of pistons

Publications (3)

Publication Number Publication Date
GB8626314D0 GB8626314D0 (en) 1986-12-03
GB2182270A true GB2182270A (en) 1987-05-13
GB2182270B GB2182270B (en) 1987-09-23

Family

ID=26286825

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08626314A Expired GB2182270B (en) 1983-09-06 1984-08-24 The manufacture of pistons

Country Status (2)

Country Link
GB (1) GB2182270B (en)
HK (1) HK52788A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2297282A (en) * 1995-01-25 1996-07-31 T & N Technology Ltd Machining pistons

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2297282A (en) * 1995-01-25 1996-07-31 T & N Technology Ltd Machining pistons
GB2297282B (en) * 1995-01-25 1997-07-23 T & N Technology Ltd Machining pistons

Also Published As

Publication number Publication date
GB8626314D0 (en) 1986-12-03
GB2182270B (en) 1987-09-23
HK52788A (en) 1988-07-22

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20000824