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 there
2、from, 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 2007 SAE International All rights reserved. No part of this publication m
3、ay 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: 724-776-4970 (outside USA)
4、 Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org J2794 ISSUED FEB2007 SURFACE VEHICLE INFORMATION REPORT Issued 2007-02 Power Cylinder Oil Consumption: Transport Mechanisms RATIONALE Not applicable. TABLE OF CONTENTS 1. SCOPE 5 1.1 Purpose. 5 2. REFERENCES 5 2.1 Ap
5、plicable Publications . 5 2.1.1 SAE Publications. 5 3. DEFINITIONS . 5 4. BASICS OF OIL TRANSPORT FOR CONSUMPTION 6 5. POWER CYLINDER COMPONENT - EFFECTS ON OIL CONTROL. 7 5.1 Piston 7 5.2 Top Ring 7 5.3 Second Ring 8 5.4 Oil Ring . 8 5.5 Cylinder Bore 8 5.6 Oil Properties 8 6. OTHER EFFECTS ON OIL
6、CONTROL 8 7. PISTON EFFECTS ON OIL CONTROL . 8 7.1 Piston Ring Grooves . 8 7.1.1 Angles (Medium Effect). 8 7.1.2 Tilt (Major Effect). 9 7.1.3 Waviness (Major Effect) 9 7.1.4 Surface Conditions (Medium Effect) . 10 7.1.5 Chamfers (Medium Effect) 10 7.1.6 Parallelism (Medium Effect) 11 7.1.7 System Ef
7、fects (Major Effect) . 11 7.1.8 Ring Groove Material (Medium Effect) . 11 7.2 Piston Lands . 11 7.2.1 Diameters (Major Effect) . 11 7.2.2 Piston Land Lengths (Medium Effect). 12 7.2.3 Piston Land Axial Profiles (Major Effect) 12 SAE J2794 Issued FEB2007 - 2 - 7.2.4 Piston Land Circumferential Profil
8、es (Minor Effect) 13 7.2.5 Piston Land Pressurization (Major Effect) 13 7.2.6 Piston Guidance by a Land (Minor Effect) 13 7.2.7 Accumulator Grooves (Major Effect). 13 7.3 Oil Drain 14 7.3.1 Oil Drain Holes (Major Effect) . 14 7.3.2 Oil Drain Slots (Major Effect) 14 7.3.3 Trans Slots (Major Effect) .
9、 15 7.3.4 Drain Along Sides of the Piston (Medium Effect) 15 7.3.5 Oil Drain to the Pin Bore . 15 7.4 Piston Skirt 16 7.4.1 Piston Guidance or Piston Secondary Motion (Major Effect) . 16 7.4.2 Skirt Surface Finish (Minor Effect) 19 7.4.3 Skirt Chamfer (Medium Effect) 19 7.5 Piston Cooling (Medium Ef
10、fect) 20 7.5.1 Connecting Rod Spray 20 7.6 Piston Temperatures (Major Effect) 21 7.6.1 Piston Thermal Distribution. 21 7.6.2 Oil Viscosities 21 7.6.3 Carbon Build Up 21 8. RING EFFECTS ON OIL CONTROL 21 8.1 General Piston Rings 21 8.1.1 Conformability (Major Effect) 21 8.1.2 Surface Conditions (Majo
11、r Effect). 22 8.2 Compression Rings. 22 8.2.1 Ring Twist (Major Effect). 22 8.2.2 Angles (Minor Effect) 23 8.2.3 Closed Gap (Major Effect) 23 8.2.4 Gap Ratios (Major Effect) . 23 8.2.5 Ring Axial Width (Medium Effect) . 23 8.2.6 Ring Mass (Major Effect) 23 8.2.7 Ring Circumferential Shape (Medium Ef
12、fect) . 23 8.2.8 Tension (Medium Effect). 24 8.2.9 Face Profile (Minor Effect) 25 8.2.10 Top Ring Face Profile (Medium Effect). 25 8.2.11 Second Ring Face Profile (Major Effect) 26 8.2.12 End Gap Chamfer (Medium Effect). 27 8.2.13 OD Chamfers (Medium Effect) 27 8.2.14 Waviness (Chatter) (Major Effec
13、t) 28 8.2.15 Straightness (Medium Effect) 29 8.2.16 Roughness (Medium Effect) . 29 8.2.17 System Effects 29 8.3 Ring Materials (Medium Effect). 29 8.3.1 Base Material (Minor Effect) . 29 8.3.2 Face Coating Material (Medium Effect) 29 8.4 Oil Control Ring. 30 8.4.1 General Oil Ring 30 8.4.2 Two Piece
14、 Oil Ring 31 8.4.3 Three Piece Oil Ring. 31 9. CYLINDER BORE EFFECT ON OIL CONTROL 33 9.1 Cylinder Bore Surface Finish (Major Effect) . 33 9.1.1 Peak Honed Bore Surfaces (Major Effect) 33 9.1.2 Plateau Honed Surface (Major Effect) 33 9.1.3 Advanced Cylinder Bore Structuring (Major Effect) 34 9.1.4 B
15、rush Honed (Minor Effect) 34 9.1.5 Surface Condition (Major Effect). 34 9.2 Cylinder Bore Honing Angle (Medium Effect). 34 SAE J2794 Issued FEB2007 - 3 - 9.3 Bore Distortion (Major Effect) 34 9.4 Carbon Scrapers on the Liner (Major Effect) 35 9.5 Cylinder Bore Material (Medium Effect) 36 10. CONNECT
16、ING ROD (MEDIUM EFFECT)36 11. OIL EFFECTS ON OIL CONTROL (MAJOR EFFECT) 36 11.1 Viscosity (Major) 36 11.2 Volatility (Medium). 36 11.3 Oil Temperature (Major) 36 11.4 Oil System Design (Medium) 36 11.5 Oil Capacity (Medium) 36 11.6 Oil Brand (Medium). 36 12. OIL JET OR OIL SQUIRTER EFFECTS ON OIL CO
17、NTROL 36 12.1 Oil Jet Targeting (Medium Effect) . 36 12.2 Oil Jet Spray Angle (Medium Effect). 37 12.3 Types of Oil Jet (Medium Effect). 37 13. PISTON PIN EFFECTS ON OIL CONTROL (MINOR EFFECT) 38 14. SYSTEM EFFECTS ON OIL CONTROL 38 14.1 Ring/Groove Side Clearance (Medium Effect) 38 14.2 Ring/Groove
18、 Back Clearance (Medium Effect). 38 14.2.1 Oil Volume Behind the Rings 38 14.2.2 Interference. 38 14.2.3 Energizing the Ring. 39 14.3 Ring Seating (Medium Effect). 39 14.4 Inter-ring Gas Pressure and Ring Dynamics (Major Effect) . 39 14.5 Interactions with Blow-By 40 14.6 Interactions with the Engin
19、e Breather. 40 15. ENGINE OPERATION 41 15.1 Engine Speed 41 15.2 Engine Load 41 15.3 Engine Maintenance . 41 15.4 Fuel Injection Effects. 41 15.4.1 Fuel Dilution 41 15.4.2 Oil Burning 41 16. QUALITY ISSUES. 42 16.1 Cylinder Bore Quality 42 16.2 Piston Quality 42 16.3 Piston Ring Quality 42 16.4 Asse
20、mbly Issues . 42 16.4.1 Upside Down Rings 42 16.4.2 Incorrect Rings in the Wrong Grooves 42 16.4.3 Missing Rings 42 16.4.4 Broken Rings. 42 16.4.5 Chipped Ring Face Coatings 42 16.4.6 Lack of Proper Lubrication During Installation 43 16.4.7 Excessive Core Sands from the Block or Head Casting 43 16.4
21、.8 Improper Torque Procedure when Assembling Cylinder Heads to Block 43 16.4.9 Improper O-Rings in the Cylinder Liner 43 SAE J2794 Issued FEB2007 - 4 - 17. OTHER EFFECTS 43 17.1 Scuffing . 43 17.2 Ring Sticking . 43 17.2.1 Micro-Welding Causing Ring Sticking. 43 17.2.2 Clearances Too Small Causing R
22、ing Sticking 43 17.2.3 Debris and Carbon Build-Up Causing Ring Sticking 43 18. HIGH MILEAGE EFFECTS. 43 18.1 Critical Wear Couples . 43 18.2 Carbon Build Up 44 18.2.1 Carbon Polishing. 44 18.2.2 Carbon Causing Ring Groove Sticking. 44 18.2.3 Carbon Scraping . 44 LIST OF FIGURES FIGURE 1 - FLOW OF OI
23、L AND GASES PAST A RING . 6 FIGURE 2 - POWER CYLINDER . 7 FIGURE 3 - ANGLES OF RINGS AND GROOVES . 9 FIGURE 4 - GROOVE UPTILT . 9 FIGURE 5 - GROOVE WAVINESS 10 FIGURE 6 - EFFECT OF THE LARGE OUTSIDE DIAMETER EDGE BREAK . 11 FIGURE 7 - LAND DIAMETERS. 12 FIGURE 8 - LAND PROFILES 12 FIGURE 9 - LAND AN
24、D SKIRT PROFILE EXAMPLE 13 FIGURE 10 - LAND ACCUMULATOR GROOVES 14 FIGURE 11 - OIL DRAIN TRANS SLOTS 15 FIGURE 12 - OIL DRAIN SLOTS . 15 FIGURE 13 - EXAMPLE OF THE EFFECT OF PIN OFFSET ON PISTON MOTION . 16 FIGURE 14 - PISTON PROFILES 17 FIGURE 15 - SKIRT AXIAL PROFILES 18 FIGURE 16 - SKIRT CIRCUMFE
25、RENTIAL CONTOURS. 19 FIGURE 17 - SKIRT CHAMFERS 20 FIGURE 18 - GALLERY COOLED PISTON. 21 FIGURE 19 - RING TWIST TERMINOLOGY . 23 FIGURE 20 EXAMPLE OF CALCULATED RING PRESSURE PATTERN. 24 FIGURE 21 ILLUSTRATION OF RING TENSION MEASUREMENTS. 25 FIGURE 22 - EFFECT OF FACE PROFILE ON NET FORCE ACTING ON
26、 THE RING . 26 FIGURE 23 - SECOND RING FACE PROFILES . 26 FIGURE 24 - END GAP CHAMFER . 27 FIGURE 25 - SCHEMATICS OF BOTTOM SIDE OD CHAMFERS. 27 FIGURE 26 - RING COATING APPLICATION EXAMPLES 28 FIGURE 27 - WAVY RING EXAMPLE 28 FIGURE 28 - RING STRAIGHTNESS EXAMPLE 29 FIGURE 29 - TWO PIECE OIL RING .
27、 31 FIGURE 30 - THREE PIECE OIL RING . 32 FIGURE 31 - PLATEAU HONED SURFACE . 33 FIGURE 32 - EXAMPLES OF THE EFFECTS OF BORE DISTORTION 35 FIGURE 33 - DIFFERENT ORDER BORE DISTORTIONS. 35 FIGURE 34 - OIL SPRAY ANGLE 37 FIGURE 35 - OIL SQUIRTER EXAMPLES 38 FIGURE 36 - SEATING FORCES ON THE RING WHEN
28、P1P2 (P1 = PRESSURE ABOVE THE RING, P2 = PRESSURE BELOW THE RING) 39 FIGURE 37 - EXAMPLES OF INTER-RING GAS PRESSURE AND RING MOTION. 40 FIGURE 38 - EXAMPLE OF THE SPEED AND LOAD EFFECT ON OIL CONSUMPTION. 41 SAE J2794 Issued FEB2007 - 5 - 1. SCOPE This document covers oil transport mechanisms from
29、the power cylinder which might affect oil consumption. It will not discuss in detail the oil consumption mechanisms from other components. 1.1 Purpose The oil consumption of an internal combustion engine is a significant performance attribute. The loss of engine oil through the combustion chamber is
30、 critical because it impacts the emissions signature of the engine and potentially poisons any exhaust gas after treatment devices. In addition, oil consumption is an attribute that directly affects the operator of a vehicle. The durability of an engine is defined, in many cases, as the point at whi
31、ch oil consumption becomes excessive. This document addresses the oil consumption transport mechanisms for the power cylinder. Other sources for oil consumption which will not be covered in this document are the turbocharger, the crankcase ventilation system, leaks, and the valve train. The material
32、 covered is appropriate for both spark ignition and compression ignition engines. The intent of this document is not to be a comprehensive oil consumption handbook. It is an introduction to the oil consumption mechanisms. Since every engine is unique, this document handles oil consumption mechanisms
33、 in a general way, leaving the specific dimensions, surface finishes, end gaps, and angles to be detailed by the power cylinder engineer for each individual engine. Consequently, the document evaluates each feature in a qualitative manner. Each source of oil consumption is evaluated by the qualitati
34、ve parameters of Major, Medium, and Minor. For example, the unit pressure of the oil ring is categorized as a major effect on in-cylinder oil consumption. In solving oil consumption problems, this feature should be explored before the piston skirt surface finish since skirt finish is categorized wit
35、h a minor rating. In addition, if a new engine is being designed specifying the unit pressure of the oil ring will be a significant step in ensuring that a new engine design will have acceptable oil control. This document does not emphasize the effect of wear on oil consumption. It applies to essent
36、ially new power cylinder components whose dimensions will change as the result of wear processes. Experience with each individual engine will determine how significant the power cylinder oil consumption is impacted by wear. This document is an introduction to understanding power cylinder oil transpo
37、rt mechanisms. The specific details of each individual engine will remain with the power cylinder development engineer. 2. REFERENCES 2.1 Applicable Publications The following publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the latest versio
38、n of SAE publications shall apply. 2.1.1 SAE Publications Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. SAE J1588 Internal Combustion EnginesPiston RingsVocabulary SAE J2612 Internal Combus
39、tion EnginesPiston Vocabulary 3. DEFINITIONS See SAE J2612, Piston Vocabulary for the piston nomenclature. See SAE J1588, Piston Ring Vocabulary for the piston ring nomenclature. SAE J2794 Issued FEB2007 - 6 - 4. BASICS OF OIL TRANSPORT FOR CONSUMPTION Fundamentally, any oil that migrates past the t
40、op ring into the combustion chamber can be lost and contribute to the oil consumption of an engine. The purpose for the power cylinder design is to seal gases and to control the oil, allowing it to lubricate the piston rings without losing it into the combustion chamber. The form of the oil migratin
41、g past the top ring into the combustion chamber can be liquid, vapor, or mist. a. Liquid: Liquid oil can be scraped, flow, and be squeezed around the ring. b. Vaporized Oil: The oil can vaporize or evaporate. This can occur while the oil is on the piston, on the liner, or in the ring-pack. In the va
42、por form, the oil can be burned or transported by gases. c. Oil in a Mist: Due to the motion of the piston and rings, and the gas flows, the oil can become a mist or aerosol. This mist can be carried in the gases that flow through the ring-pack. FIGURE 1 - FLOW OF OIL AND GASES PAST A RING SAE J2794
43、 Issued FEB2007 - 7 - 5. POWER CYLINDER COMPONENT - EFFECTS ON OIL CONTROL The following power cylinder components each can contribute to oil consumption. These effects will be described in subsequent sections. Components Piston Rings Top Compression Ring Second Compression Ring Oil Control Ring Cyl
44、inder Bore Oils Oil Jets Under-crown Spraying Gallery Cooling Sprays Piston Pin Connecting Rod FIGURE 2 - POWER CYLINDER 5.1 Piston The oil flowing past the piston contributes to the oil consumption of the engine. The piston must provide for accumulation and drainage of excess oil. The grooves and l
45、ands should be designed to control the gas and oil flow around the rings and through the ring gaps. The piston top land can scrape oil into the combustion chamber if not designed properly or if it has excessive carbon that builds-up during engine operation. The design of the piston skirt will also i
46、nfluence oil consumption. The secondary motion of the piston must be controlled in order to allow the rings to perform their function. 5.2 Top Ring The top ring is the primary seal for the combustion gases and as a result has the most significant effect on blow-by. However, the top ring is the final
47、 obstacle before the oil is transported into an area where it can be consumed. Thus the top ring is also important for oil control. SAE J2794 Issued FEB2007 - 8 - 5.3 Second Ring The second ring primarily scrapes the excess oil off the bore surface that passes by the oil ring. As a result it is very
48、 important for good control of oil consumption. 5.4 Oil Ring The oil ring reduces the oil film thickness from that required for piston skirt lubrication to that required for compression ring lubrication. 5.5 Cylinder Bore The interaction of the piston and rings with the bore surface affects the gas
49、and oil sealing of the cylinder. As a result, it is the function of the cylinder bore to provide a good sealing surface with sufficient but not excessive oil retention for the lubrication of the piston and rings. The conditions of the bore (temperatures, distortion, surface finish, etc.) also need to be optimized for proper oil control. 5.6 Oil Properties The properties of the oil play a significant role in oil con
