SAE J 2798-2014 Power Cylinder Blow-by Problem Solving《动力气缸窜漏 解决问题》.pdf

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 revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright 2014 SAE International All rights reserved. No part of this pub

3、lication may 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

4、(outside USA) 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/J2798_201408SURFACE VEHICLEINFORMATION REPORTJ2798REV.AUG2014Issued 2007-04 Revised

5、2014-08 Superseding J2798 APR2007Power Cylinder Blow-by: Problem Solving RATIONALENew engineers or engineers that are not experienced in power cylinder development may not always have the necessary background to develop the optimum engines or solve problems that are experienced. This document gives

6、basic background information that will help engineers working with power cylinders with the knowledge that they need to help them be more effective. TABLE OF CONTENTS 1. SCOPE 31.1 Purpose . 32. REFERENCES 43. DEFINITIONS . 44. LIST OF METHODS 45. CHECK THE HISTORY OF THE ENGINE . 46. ELIMINATE THE

7、SIMPLE POSSIBILITIES (BEFORE ENGINE TEARDOWN) . 56.1 Check for Malfunctioning Blow-by Measurement Transducer 56.2 Check for Malfunctioning External Components 56.3 Check for Coolant in the Oil 56.4 Check for Fuel in the Oil . 56.5 Compression Check 56.6 Leak Down Test 56.7 Cracked Head or Block. 56.

8、8 Borescope the Engine . 66.9 Examine the Color of the Exhaust 6SAE INTERNATIONAL J2798 Revised AUG2014 Page 2 of 19 7. ELIMINATE THE POTENTIAL MISTAKES (AFTER ENGINE TEARDOWN) 67.1 Incorrect, Missing, or Misassembled Components . 67.1.1 Broken Parts . 67.1.2 Abnormal Marks 67.1.3 Improperly Handled

9、 Rings 78. HIGH BLOW-BY AS A RESULT OF A FAILURE . 78.1 Broken Rings . 78.2 Face Coating Failure . 88.3 Scuffed Power Cylinder 88.4 Carbon Deposits on the Piston Top Land and Top Ring Groove . 88.4.1 Carbon Buildup on the Top Land 88.4.2 Carbon Buildup in the Top Ring Groove . 98.4.3 Carbon Tracking

10、 . 98.5 Excessive Wear 98.6 Debris 108.7 Lack of Lubrication 108.8 Bore Washing from the Fuel . 108.9 Oil Burning from the Cylinder Wall 109. CHECK FOR PROPER DESIGN 1110. MODELING AND MAPPING . 1110.1 Cylinder Kit Dynamics . 1110.2 Engine Blow-by Steady State Mapping 1211. COMPONENT SWAPPING AND VA

11、RIATION TECHNIQUES 1211.1 Swapping Technique 1211.2 Variation Technique 1212. SYSTEM SEPARATION . 1312.1 Isolating the Overhead 1312.2 Isolating the Turbocharger/Supercharger . 1312.3 Isolating the Crankcase Ventilation Systems 1312.4 Isolating the External Components . 1313. OTHER POSSIBLE FACTORS

12、1313.1 Customer Duty Cycle 1314. BLOW-BY PROBLEM SOLVING SEQUENCE BLOW-BY HAS BECOME BAD 1414.1 Before Disassembly of the Engine 1414.1.1 Check the History 1414.1.2 Investigate the Source 1414.1.3 Check for Problems 1414.2 Minimal Disassembly of the Engine 1414.3 Remove the Cylinder Head. 1414.4 Rem

13、ove the Power Cylinder Components 1514.4.1 Check for Incorrect Installation Issues 1514.4.2 Check for Damage 1514.4.3 Evaluate the Components . 1514.4.4 Check for Wear . 1514.4.5 Check for Manufacturing Issues . 15SAE INTERNATIONAL J2798 Revised AUG2014 Page 3 of 19 15. BLOW-BY PROBLEM SOLVING SEQUE

14、NCE BLOW-BY IS HIGH BUT ACCEPTABLEON OTHER ENGINES 1615.1 Before Disassembly of the Engine 1615.1.1 Check the History 1615.1.2 Investigate the Source 1615.1.3 Check for Problems 1615.2 Minimal Disassembly of the Engine 1615.3 Remove the Cylinder Head. 1615.4 Remove the Power Cylinder Components 1715

15、.4.1 Check for Assembly Issues . 1715.4.2 Check for Damage 1715.4.3 Evaluate the Components Visually . 1715.4.4 Check for Manufacturing Issues . 1715.5 Swap Testing 1816. BLOW-BY PROBLEM SOLVING SEQUENCE BLOW-BY IS ALWAYS HIGH . 1816.1 Before Disassembly of the Engine 1816.1.1 Check the History 1816

16、.1.2 Investigate the Source 1816.2 Remove the Head . 1816.3 Remove the Power Cylinder Components 1816.3.1 Evaluate the Components Visually . 1816.3.2 Check for Manufacturing Issues . 1916.4 Evaluate the Design 1916.5 Model the Power Cylinder Dynamics 1916.6 Variation Testing . 1917. NOTES 1917.1 Mar

17、ginal Indicia . 19FIGURE 1 EXAMPLE OF DAMAGED TO THE THIRD LAND DUE TO INSTALLATION DAMAGE . 7FIGURE 2 EXAMPLE OF BROKEN PISTON RING 7FIGURE 3 EXAMPLE OF FAILED RING FACE COATINGS . 8FIGURE 4 EXAMPLE OF PISTON SCUFF 8FIGURE 5 EXAMPLE OF CARBON POLISHING 9FIGURE 6 EXAMPLE OF CARBON TRACKING CAUSED BY

18、 EXCESSIVE BORE DISTORTION . 9FIGURE 7 EXAMPLES OF EXCESSIVELY WORN RINGS 10FIGURE 8 EXAMPLE OF EXCESSIVE POLISH DUE TO BORE WASHING OR OIL BURNING 11FIGURE 9 EXAMPLE OF INTER-RING GAS PRESSURE AND RING MOTION . 121. SCOPE This document describes methodologies to determine the causes blow-by oil con

19、sumption caused by the power cylinder. 1.1 Purpose During the combustion event, the intent of the engine design is to contain the combustion gases in the combustion chamber to load the piston and drive the piston to turn the crankshaft. It is the intent of the power cylinder system to seal the gases

20、 and to control the oil film on the power cylinder parts. The gas that escapes around the rings and piston is referred to as blow-by gases or just blow-by. The power cylinder system and individual components are designed to seal the gases. The understanding associated with which features affect blow

21、-by is important in the engine design and development process.SAE INTERNATIONAL J2798 Revised AUG2014 Page 4 of 19 When diagnosing blow-by problems the engineer must be aware that other engine systems can affect blow-by. These systems are as follows: x Power cylinder system (piston, rings, liner) x

22、Head gasket x Cylinder head system (valves, valve stem guides and seals, etc.) x Turbocharger x Supercharger x Air compressors This document describes general methods for determining the causes of high blow-by so that it might be corrected. 2. REFERENCES There are no referenced publications specifie

23、d herein. 3. DEFINITIONS There are no unique definitions. 4. LIST OF METHODS The following is a list of the basic methods for determining the causes of high blow-by: x Check the History of the Engine x Eliminate the Simple Possibilities x Eliminate the Mistakes x High Blow-by as a Result of a Failur

24、e x Modeling and Mapping x Component Swapping and Variation Techniques x System Separation 5. CHECK THE HISTORY OF THE ENGINE High blow-by may be a result of how the engine was operating. Make sure that the engine was run properly. Some of the areas to check on engine operation are: x Check for sudd

25、en changes in the blow-by. This might indicate a problem in the engine. x Check the history for changes in temperatures and/or pressures that might indicate incorrect engine operation or problems:x Oil x Coolant x Intake x Exhaust x Check for incorrect engine operation. x Speed x Load x Check warran

26、ty data to determine if the engine has a history of problems and under what conditions. x Check the history of past engine test done on the same engine configuration. Have things changed? Was the engine run differently? SAE INTERNATIONAL J2798 Revised AUG2014 Page 5 of 19 6. ELIMINATE THE SIMPLE POS

27、SIBILITIES (BEFORE ENGINE TEARDOWN) When there is a problem with high blow-by of an engine, it is important to eliminate the simple potential causes first. These are the things that are done prior to any engine teardown. 6.1 Check for Malfunctioning Blow-by Measurement Transducer Investigate the blo

28、w-by measurement transducer for indications that it is malfunctioning. It is common for some transducers to be affected by oil that gets trapped in the device. Check to make sure the calibration of the device is correct.6.2 Check for Malfunctioning External Components Components other than the power

29、 cylinder may contribute to high blow-by. Check these components for potential problems that may result in blow-by problems. Turbocharger/Supercharger - Can often be isolated from the main engine to determine the turbocharger/supercharger contribution to blow-by. Valve Guides - Gases may flow around

30、 the valve stems. Replace the valve stem seals if possible. 6.3 Check for Coolant in the Oil Coolant in the cylinder will vaporize causing high blow-by. Also it will affect lubricity of the oil and result in high wear ofthe cylinder walls that will affect blow-by and oil consumption. Coolant in the

31、oil could also indicate a failed cylinder head gasket which could cause high blow-by and / or oil consumption. Coolant in the oil can be determined by an oil analysis. Foam on the oil or increasing sump levels can be a sign of coolant in the oil. 6.4 Check for Fuel in the Oil Excessive fuel in the o

32、il will affect the lubricity of the oil and result in high wear of the cylinder walls that will affect blow-by.Fuel in the oil can be determined by an oil analysis. Low oil viscosity or increasing sump levels can be a sign of fuel in the oil. 6.5 Compression Check A compression check can help to det

33、ermine if there is a problem with the rings, valves, gaskets, cylinder head, or pistons that might be resulting in high blow-by. 6.6 Leak Down Test A leak down test can follow a compression check to identify the source of the leak. Look for signs of leaking in the intake ports, exhaust ports, crankc

34、ase, or coolant. Signs for leaks may be leakage noise in the ports and crankcase, or gas bubbles in the coolant. This test makes it possible to better understand whether the power cylinder (piston and rings) is the source of the blow-by. 6.7 Cracked Head or Block Investigate the engine for signs of

35、a cracked head or block which will cause high blow-by. Signs of this might include water in the oil and gases in the coolant. SAE INTERNATIONAL J2798 Revised AUG2014 Page 6 of 19 6.8 Borescope the Engine A borescope of the cylinder will help to identify if there has been scuffing or piston damage, v

36、alve burning damage, or other in-cylinder damage that has occurred that might explain the cause of high blow-by. 6.9 Examine the Color of the Exhaust The color of the exhaust gases might indicate problems: x Excessive white smoke might indicate coolant in the cylinder x Excessive black smoke might i

37、ndicate excessive fuel. 7. ELIMINATE THE POTENTIAL MISTAKES (AFTER ENGINE TEARDOWN) 7.1 Incorrect, Missing, or Misassembled Components x Have the correct pistons been used? x Are all the correct piston rings on the piston? x Are there any missing piston rings? x Are all the rings orientated correctl

38、y with the proper side up? 7.1.1 Broken Parts Check all the piston rings for breakage. Piston rings may have been broken during operation or during assembly. Rings that were broken on assembly can often be identified by damage to the piston. The broken ends of the rings become polished against the c

39、ylinder bore and / or against each other during running if they were broken at assembly or during running. If they were broken during or after tear-down, the broken ends are not polished. Broken ring lands on the piston would also be a cause of high oil consumption and blow-by. It may be necessary t

40、o remove the rings to determine whether any ring lands are cracked or broken. Look for cracks on the cylinder head and also for damage on the head gasket. 7.1.2 Abnormal Marks Installation Errors: Check the pistons and rings for abnormal markings. This could be an indication of assembly damage. Look

41、 for manufacturing issues such as signs of waviness in the piston rings. SAE INTERNATIONAL J2798 Revised AUG2014 Page 7 of 19 FIGURE 1 - EXAMPLE OF DAMAGED TO THE THIRD LAND DUE TO INSTALLATION DAMAGE 7.1.3 Improperly Handled Rings A piston ring that is overextended or excessively twisted during ins

42、tallation might break in operation or show abnormal marks on the face of the ring. 8. HIGH BLOW-BY AS A RESULT OF A FAILURE High blow-by will be caused by failure of components. This must be determined when investigating the cause of high blow-by. In the subsequent sections there are a few examples

43、of failures that may result in high blow-by. 8.1 Broken Rings A broken piston ring can easily be found and can result in high oil consumption and high blow-by. FIGURE 2 - EXAMPLE OF BROKEN PISTON RING SAE INTERNATIONAL J2798 Revised AUG2014 Page 8 of 19 8.2 Face Coating Failure Failure of the top ri

44、ng face coating will result in high blow-by. FIGURE 3 - EXAMPLE OF FAILED RING FACE COATINGS 8.3 Scuffed Power Cylinder Blow-by will be high if the cylinder is scuffed. Scuffing will be an obvious failure. FIGURE 4 - EXAMPLE OF PISTON SCUFF 8.4 Carbon Deposits on the Piston Top Land and Top Ring Gro

45、ove 8.4.1 Carbon Buildup on the Top Land Excessive carbon deposits on the top land are a sign that the ring pack is not effectively sealing the oil. Problems with carbon build-up include: x Polishing of the cylinder walls. x Scraping oil upward from the carbon that is built up. x Potential lack of a

46、bility to energize the top ring because the carbon blocks the pressure build-up. SAE INTERNATIONAL J2798 Revised AUG2014 Page 9 of 19 FIGURE 5 - EXAMPLE OF CARBON POLISHING Inspect the top ring groove for excessive carbon deposits which can cause the top ring to be stuck and ineffective. Carbon in t

47、he top ring groove which makes the top ring ineffective is typically accompanied by high blow-by. 8.4.2 Carbon Buildup in the Top Ring Groove Excessive carbon packing in the ring groove may decrease its effectiveness to seal the gases and oil because: x The ring may stick in the groove. x There may

48、be interference between the ring and the carbon in the groove. 8.4.3 Carbon Tracking Carbon tracking around a piston ring might be a sign of a leakage path for the blow-by gases that needs to be investigated.FIGURE 6 - EXAMPLE OF CARBON TRACKING CAUSED BY EXCESSIVE BORE DISTORTION 8.5 Excessive Wear Excessively worn rings can result in hig