1、_SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising theref
2、rom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2010 SAE International All rights reserved. No part of this publication ma
3、y be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-4970 (outside US
4、A) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J2612_201005SURFACEVEHICLESTANDARDJ2612 MAY2010 Issued 2002-01 Revised 2010-05 Superseding J261
5、2 JAN2002 Internal Combustion EnginesPiston Vocabulary RATIONALEThis standard has been created to standardize nomenclature and definitions for pistons. TABLE OF CONTENTS 1. SCOPE AND FIELD OF APPLICATION . 22. REFERENCES 23. DEFINITIONS . 34. COATING ALPHABETICAL INDEX (COMMON COATINGS) . 104.1 Anod
6、izing (Hard) . 104.2 Chrome . 104.3 Resin Bonded Anti-Friction Coating (e.g. Graphite) . 104.4 Iron 104.5 Lead 104.6 Nickel Composite Coating (NCC) . 104.7 Phosphate . 104.8 PTFE . 104.9 Tin . 105. COATINGS FUNCTIONAL INDEX (COMMON COATINGS) . 105.1 Lubrication Coatings . 105.2 Thermal Crack Prevent
7、ion 115.3 Microwelding Protection 115.4 Corrosion Protection . 115.5 Friction Reduction . 115.6 Noise Abatement . 115.7 Wear Reduction 116. PISTON BLANK PRODUCTION PROCESSES . 116.1 Gravity Casting 116.2 Squeeze Casting . 116.3 Pressure Diecasting 116.4 Forging 116.5 Gravity Sand Casting 127. ARTICU
8、LATED PISTON NOMENCLATURE . 12SAE J2612 Revised MAY2010 Page 2 of 388. MONOBLOCK PISTON NOMENCLATURE . 178.1 Medium/Heavy Duty 178.2 Light Duty 219. TWO-STROKE 2510. CATEGORY INDEX 3311. ALPHABETICAL FEATURE INDEX . 3612. NOTES 3812.1 Marginal Indicia . 38FIGURE 1 ARTICULATED PISTON . 12FIGURE 2 ART
9、ICULATED PISTON CROWN - VIEW ALONG THRUST AXIS 13FIGURE 3 ARTICULATED PISTON CROWN - VIEW ALONG PIN AXIS . 14FIGURE 4 ARTICULATED PISTON - RING BELT REGION . 15FIGURE 5 ARTICULATED PISTON SKIRT . 16FIGURE 6 MEDIUM/HEAVY DUTY MONOBLOCK PISTON 17FIGURE 7 MEDIUM/HEAVY DUTY MONOBLOCK PISTON: VIEW ALONG
10、THRUST AXIS 18FIGURE 8 MEDIUM/HEAVY DUTY MONOBLOCK PISTON: VIEW ALONG PIN AXIS . 19FIGURE 9 MEDIUM/HEAVY DUTY MONOBLOCK PISTON: RING BELT REGION 20FIGURE 10 LIGHT DUTY MONOBLOCK PISTON - ISOMETRIC VIEW 21FIGURE 11 LIGHT DUTY MONOBLOCK PISTON - TOP AND SIDE VIEW . 22FIGURE 12 LIGHT DUTY MONOBLOCK PIS
11、TON: CUTAWAY VIEWS . 23FIGURE 13 LIGHT DUTY MONOBLOCK PISTON: PROFILES 24FIGURE 14 TWO-STROKE DIRECT INJECTION PISTON (LOOP SCAVENGED) . 25FIGURE 15 TWO-STROKE ELECTRONIC FUEL INJECTION PISTON (LOOP SCAVENGED) . 26FIGURE 16 TWO-STROKE CROSS SCAVENGED PISTON 27FIGURE 17 COMPARISONS OF PISTON DESIGN F
12、OR TOP GUIDED/BOTTOM GUIDEDCONNECTING RODS 28FIGURE 18 STAKING PIN VERTICAL, RADIAL STOP . 29FIGURE 19 STAKING PIN HORIZONTAL, LATERAL STOP 30FIGURE 20 STAKING PIN HORIZONTAL, RADIAL STOP . 31FIGURE 21 EXAMPLE OF A COMPOSITE PISTON . 32TABLE 1 33TABLE 2 361. SCOPE AND FIELD OF APPLICATION This SAE s
13、tandard defines the most commonly used terms for pistons. These terms designate either types of pistons or certain characteristics and phenomena of pistons. The terms and definitions apply to pistons for reciprocating internal combustion engines and compressors working under analogous conditions. 2.
14、 REFERENCES There are no references in this document SAE J2612 Revised MAY2010 Page 3 of 383. DEFINITIONS 3.1 Alfin Bond A special casting process used to metallurgically bond a cast iron or Ni-Resist ring groove reinforcement to the piston aluminum alloy. This method is also used to bond cylinder l
15、iners in air-cooled engines.3.2 Anti-thrust Side The piston skirt side opposite the thrust side. (This is also called the Minor Thrust Side)3.3 Apparent Density A relationship of piston mass to cylinder bore size. Also referred to as K-factor it is determined by dividing piston weight in grams by th
16、e bore diameter (in centimeters) cubed. 3.4 Articulated Two-piece piston having separate crown and skirt pieces, joined by the wrist pin and able to rotate independently about the pin. 3.5 Bottom Guided Connecting Rod Piston Design The connecting rod is located along the axis of the wrist pin by cre
17、ating a small clearance between the large or “bottom“ end of the connecting rod and the crankshaft. This allows a relatively large axial clearance between the inner sides of the wrist pin bosses and the small or “top“ end of the connecting rod. The inner sides of the wrist pin bosses are typically “
18、as cast“ for this piston design. 3.6 Coatings See Section 4. 3.7 Combustion Bowl Recessed area on the crown. The bowl adds clearance volume to the combustion chamber reducing compression ratio. The shape may also enhance combustion and provide for valve clearance. 3.8 Combustion Bowl Reinforcement A
19、 formed ceramic fiber material that is mechanically bonded within the alloy of an aluminum piston, usually at the combustion bowl rim, for increased fatigue resistance. 3.9 Combustion Bowl Rim The OD edge of the combustion bowl at the top of the piston. 3.10 Combustion Bowl Rim Remelt A process whic
20、h remelts the Aluminum in the bowl rim to improve the mechanical properties. 3.11 Compression Height The distance from the centerline of the pin bore to the top of the piston. 3.12 Composite Piston A piston where two pieces are bolted together (See Figure 21). SAE J2612 Revised MAY2010 Page 4 of 383
21、.13 Cooling Gallery A channel behind the piston ring belt area that receives cooling oil from an oil nozzle attached to a pressurized oil gallery. This channel can be formed by various methods. 3.14 Cooling (Shaker) Tray A tray at the top of the articulated piston skirt that is designed to carry oil
22、 so that it can splash up into the cooling channelof the piston. 3.15 Cover Plate A plate that encloses the cooling channel on an articulated piston. One hole in the cover plate allows sprayed oil to enter. Oil is splashed around inside the cooling channel. Oil then exits another hole in the cover p
23、late at the opposite side of the piston. 3.16 Crevice Volume Any space that traps unburned combustion gases. Trapped unburned gases when later released contribute to hydrocarbon emissions. The spaces within the ring belt, head gasket, valves, and spark plug are potential sources for crevice volume.
24、3.17 Croaking Noise Relatively low frequency noise typically caused by impact of a flexible part of the piston skirt with the cylinder bore due to secondary motion, during warm-up. (This is sometimes referred to as piston slap noise.)3.18 Cross Scavenged Engine A type of two-stroke engine where the
25、incoming charge is directed upward into the combustion chamber with a deflector on the piston. See scavenging deflector. The ports of this type of engine are commonly machined through the cylinder wall such that the intake charge enters diametrically opposite the exhaust port. 3.19 Crown Top of the
26、piston. This surface, also referred to as the dome, is part of the combustion chamber and sometimes includes a combustion bowl, crown pop-up, or valve pockets. 3.20 Crown Height For an articulated piston crown, the distance from the bottom of the strut to the top of the piston. 3.21 Crown Pop-up Rai
27、sed portion on the crown of the piston that enhances combustion by either its shape or by reducing the clearance volume (higher compression ratio). 3.22 Crown Strut For an articulated piston, the support that holds the piston pin and transfers the force exerted on the crown to the pin. 3.23 Diameter
28、-over-pins To define the width of a keystone groove it is common to measure the diameter over gage pins. Gage pins (of a specified diameter) are put in the ring grooves and the diameter to the outermost edge of the pin is the “diameter-over-pins.” Increasing the groove width will decrease the diamet
29、er-over-pins. SAE J2612 Revised MAY2010 Page 5 of 383.24 Eutectic (a) The isothermal (constant temperature) reversible reaction of a liquid that forms two different solid phases (aluminum and silicon in pistons) during cooling. (b) The alloy composition that freezes at constant temperature, undergoi
30、ng the eutectic reaction completely. (c) The alloy structure of two (or more) solid phases formed from the liquid eutectically. (also Hyper-eutectic and Hypo-eutectic.)(d) A term commonly used to describe a piston alloy having around 11.5 to 12.0 % Silicon. 3.25 Fixed Pin The piston pin is not free
31、to rotate other than when the connecting rod pivots about the crankshaft. The pin is generally restrained by an interference fit in the connecting rod small end or, less commonly, in the piston. 3.26 Floating Pin The piston pin is free to rotate. It is restrained axially by retainer rings or other d
32、evices at its ends which keep the pin centered in the piston/rod assembly. Occasionally a floating pin is assembled with slight interference fit in the piston pin bore at ambient temperature. Clearance occurs when engine combustion temperature causes the pin bore to expand. 3.27 Front Orientation Ma
33、rk The mark on the piston that indicates the orientation of the piston for installation. The mark should be placed towards the front of the engine. 3.28 Gage Pin Used to measure the diameter-over-pins dimension (typically for keystone ring groove widths). 3.29 Groove Bottom Side Angle The angle on t
34、he bottom side of a keystone ring groove. 3.30 Groove Included Angle The angle enclosed by the bottom side and top sides of a keystone groove. 3.31 Groove OD Chamfer The chamfer at the OD edge of the ring groove. 3.32 Groove Pound-out A widening of the piston ring groove caused by the ring pounding
35、or impacting itself into the aluminum groove sides. Conditions leading to groove pound-out include groove wear, an un-reinforced ring groove, high piston temperatures, detonation, and lower silicon alloys to name a few. Top side pound-out can be caused by engine speed and ring inertia. Bottom side p
36、ound-out is a function of pressure, temperature, and groove surface metallurgy. Groove pound-out can also lead to ring breakage when clearances become too large. 3.33 Groove Radial Tilt (SAE J2275) SAE J2612 Revised MAY2010 Page 6 of 383.34 Groove Root Diameter The diameter at the back of the ring g
37、roove. 3.35 Groove Root Fillet Radius The fillet radius at the inner corners of the ring grooves. 3.36 Head Land/Top Land The piston land above the top ring. 3.37 Head Land Ring An L-shaped top ring designed to function at the top of the piston crown. 3.38 Hyper-eutectic Piston aluminum alloys with
38、a silicon percentage greater than the 12% eutectic point. Primary silicon particles exist in the alloy since the quantity of silicon exceeds the solubility limit. (also eutectic) 3.39 Hypo-eutectic Piston aluminum alloys with a silicon percentage less than the 12% eutectic point. (also eutectic) 3.4
39、0 Inter-ring Volumes The volume between any two piston rings. This volume, when filled with blow-by gas, can influence the motion and function of the compression rings. This volume can also accumulate oil which may affect oil consumption. 3.41 K-factor See apparent density. 3.42 Land height The axia
40、l width of the land at the OD of the piston. 3.43 Loop Scavenged Engine A type of two-stroke engine where the incoming charge is directed upward into the combustion chamber by means of transfer ports in the cylinder. Multiple transfer ports located opposite one another are used to create a flow that
41、 is aimed away from the exhaust port and up into the combustion chamber such that the flow path takes on the shape of a loop. A scavenging deflector on the piston is not required because the porting directs the airflow. 3.44 Lubrication Slot Axial machined grooves in pin bores that provide path for
42、oil to lubricate pin/bore interface (sometimes referred to as pinbore slots). If machined wider, these slots can also provide clearance for pin ovalization caused by combustion loading (sometimes referred to as ovalization slots or side relief).3.45 Microwelding The adhesive removal of aluminum pist
43、on material, during engine operation, from the piston groove side face (most commonly on the bottom side), and potential transfer to the side of piston ring. Frequently associated with elevated piston groove temperature, poor lubrication conditions, rougher ring or groove side surface finish, and ri
44、ng to groove contact pressure. Severity ranges from microscopic levels with no observable effect to large scale damage where the sealing function is adversely affected.SAE J2612 Revised MAY2010 Page 7 of 383.46 Monoblock A term for a piston design comprised of one material and one piece construction
45、. May contain inserts such as a ring carrier.3.47 Ni-Resist A special cast iron alloy with high levels of nickel used as a piston insert for ring-groove reinforcement in aluminum pistons. Ni-Resist is ideal for this application since its coefficient of thermal expansion, 19.3 10-6mm/(mm C), nearly m
46、atches that of piston aluminum alloys, 19.0 to 21.6 10-6mm/(mm C). Normally installed in the piston casting using the Alfin bond process. 3.48 Oil Drain Hole A hole in the oil ring groove that provides a path for the oil scraped by the piston rings to return to the inside of the pistonand back to th
47、e oil sump. These are commonly put in the back of the ring groove but may be put on the bottom side. The intent is that oil will drain from the ring belt back down into the sump. However, if it is incorrectly designed, this can feedoil into the ring groove causing high oil consumption. 3.49 Oil Drai
48、n Slots Radial slots in the bottom side of the oil ring groove that provide a path for oil scraped by the piston rings to return to theoil sump at the outside of the piston. The slot will commonly extend the whole depth of the ring groove and into the back of the groove. The slots are commonly place
49、d in the pin axis so that oil will drain down the sides of the piston. 3.50 Panel The wall that connects the pin boss and the skirt. 3.51 Pin Boss Pier or Pin Boss Support The transition from pin bore to crown.3.52 Pin Bore Slot Axial machined grooves in pin bores that provide path for oil to lubricate pin/bore interface (sometimes referred to as lubrication slots). If machined wider, these slots can also provide clearance for pin ov
