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
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4、 Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org J2796 ISSUED FEB2007 SURFACE VEHICLE INFORMATION REPORT Issued 2007-02 Power Cylinder Oil Consumption: Methods of Measurements RATIONALE Not applicable. TABLE OF CONTENTS 1. SCOPE 2 1.1 Purpose. 2 2. REFERENCES 2 3.
5、DEFINITIONS . 2 4. BASIC METHODS OF MEASUREMENT . 2 4.1 Oil Lost Methods . 2 4.2 Constant Level Methods . 3 4.3 Oil Tracer Methods . 3 4.4 Indirect Measurement Methods 3 5. OIL LOST MEASUREMENT METHODS 3 5.1 Dip Stick Method or Level-Top-Up-Method 3 5.2 Weep Hole Method . 4 5.3 Drain and Weigh Syste
6、m 5 5.4 Calibrated Loss Measurement 6 6. CONSTANT LEVEL MEASUREMENT METHODS 7 6.1 Common Level System. 7 6.2 Direct Level System 8 6.3 Oil Pump System 9 7. TRACING METHODS. 10 7.1 Radiometric Tracing 10 7.2 Elemental Tracing . 11 8. INDIRECT METHODS 12 8.1 Emissions Measurement. 12 8.2 Exhaust Filte
7、r Plugging and Catalyst Poisoning. 12 SAE J2796 Issued FEB2007 - 2 - 9. MEASUREMENT CAPABILITY 12 10. COMPARISON MATRIX. 14 LIST OF FIGURES FIGURE 1 - EXAMPLE OF AN AUTOMATED DRAIN AND WEIGH SYSTEM . 6 FIGURE 2 - OIL LEVEL MEASUREMENT SYSTEMS. 6 FIGURE 3 - GRAVITY FED OIL CONSUMPTION MEASUREMENT TEC
8、HNIQUE 7 FIGURE 4 - EXAMPLE OF A DIRECT LEVEL MEASUREMENT SYSTEM USING A PRESSURE SENSOR. 8 FIGURE 5 - OIL PUMP METHOD FOR MEASURING OIL CONSUMPTION9 FIGURE 6 - EXAMPLE OF MONITORING THE COEFFICIENT OF VARIANCE DURING AN OIL CONSUMPTION TEST . 13 1. SCOPE This document describes the major techniques
9、 for measuring oil consumption. It does not cover all the sub variations that might be used to make this measurement. 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 critical because it
10、impacts the emissions signature of the engine and potentially poisons any exhaust gas after treatment devices. Also the level of oil consumption is an important quality perception to the customer. The engine should not have to require any add oil between oil changes. While developing new engines or
11、solving oil consumption problems on existing engines, it is important to be able to measure the oil consumption of an engine and have confidence in that measurement. The purpose of this document is to review the different measurement methods, outlining their fundamental operating principles, their a
12、dvantages, and their disadvantages. There is no attempt to identify the best measurement method because the best method will depend on the situation, the objectives, and on capabilities of the organization. 2. REFERENCES There are no referenced publications specified herein. 3. DEFINITIONS There are
13、 no unique definitions. 4. BASIC METHODS OF MEASUREMENT Oil consumption measurement methods can be divided into a few major categories. All of the current measurement methods can be listed under each of these categories. 4.1 Oil Lost Methods With this technique, the amount of oil is recorded at the
14、beginning of the test. At defined measurement times, the amount of oil lost is determined and recorded as the oil consumed. Oil lost methods include: Dip Stick Method Weep Hole Method Drain and Weigh Method Calibrated Loss Method SAE J2796 Issued FEB2007 - 3 - 4.2 Constant Level Methods In these met
15、hods, the system is set up to maintain a constant oil level in the oil pan. The oil rate addition to the engine to maintain a constant oil level is a measurement of the oil consumption. Constant level methods include: Common Level Systems Direct Level Systems Oil Pump System 4.3 Oil Tracer Methods O
16、il tracer techniques utilize tracer elements in the oil that can be measured in the exhaust when the oil is consumed. Oil tracer methods include: Radiometric tracing Elemental tracing Emissions measurements 4.4 Indirect Measurement Methods Indirect methods for measuring oil consumption include: Emis
17、sions are often a primary concern which drives the need for low oil consumption. Therefore, oil control can be evaluated indirectly through emissions measurements. Plugging of the exhaust filters can also be an indication of how much oil the engine is consuming. Poisoning of the catalyst is also aff
18、ected by the oil consumed. 5. OIL LOST MEASUREMENT METHODS 5.1 Dip Stick Method or Level-Top-Up-Method This is the simplest method of all, but probably the least accurate. This method consists of filling the engine with oil to a specified level on the dipstick. The engine is run, during which time o
19、il is consumed. The engine is shut down and allowed to cool. It is important to specify and control the cool down period. The level is again measured with the dipstick. A measured amount of oil is added to bring the oil level back up to the initial level. The amount of oil added is considered to be
20、the amount of oil consumed. Notes Before establishing the initial oil level for this type of test, the engine should be run first to fill the filters and passages with oil. Otherwise there will be a false first oil consumption measurement reading. Internal drain back of oil within the engine to the
21、sump can significantly affect this measurement. Drain back time and position of the engine crank may affect this. The installation angle of the engine may affect how the oil drains within the engine. Oil level measurements should be made at consistent oil sump temperatures. A calibrated dipstick wit
22、h inscribed marks can help improve accuracy of this method. Advantages The dip stick method is very simple. No extra equipment is needed to measure oil consumption. This type of measurement can be made on field test engines. However, to get accurate data, a precise and consistent oil fill procedure
23、must be followed. SAE J2796 Issued FEB2007 - 4 - Disadvantages The dip stick method takes a long test time to get acceptable results. The accuracy will be improved with longer test duration and multiple measurements. The results are not very accurate nor repeatable. They depend on how well the oil l
24、evel can be determined on the dipstick and the accuracy in adding oil. Inconsistent drain back of oil in the engine can cause erroneous results. Inconsistent oil sump temperatures may result in errors. Oil leaks from the engine will be measured as oil consumption unless external leakage is quantifie
25、d and subtracted from gross consumption. The system is very operator dependent. Fuel or coolant dilution in the oil will influence the measured level of oil consumption. Extended duration of operation required to get a reading makes it difficult to study break-in effects. 5.2 Weep Hole Method The we
26、ep hole method for measuring oil consumption is very simple in concept but offers the potential to be a little more accurate than the dip stick method. However, it uses the same principle as the dip stick method. A hole is drilled into the oil pan at a specified level in the oil pan. This should cor
27、respond to some location between the high and low marks on the dip stick. The hole is opened and oil is added until it starts to leak out of the weep hole. All of the excessive oil is allowed to leak out of the weep hole. The hole is again closed. The engine is run at the desired conditions and any
28、oil added during the test is recorded. At the end of the test, oil is added so that the oil level in the pan slightly exceeds the weep hole level. The amount of oil added is recorded. The weep hole is opened and all of the oil that leaks out is captured, measured, and recorded. The oil consumption i
29、s the sum of the oil added during the test plus the difference of the oil added at the end of the test minus the amount of oil that leaks out of the hole at the end of the test.” Notes Before establishing the initial oil level for this type of test, the engine should be run first to fill the filters
30、 and passages with oil. Otherwise there will be a false first oil consumption measurement reading. Internal drain back of oil within the engine to the sump can significantly affect this measurement. Drain back time and position of the engine crank may affect this. Drain time from the engine can also
31、 affect this measurement. The installation angle of the engine may affect how the oil drains within the engine. Oil measurements should be made at consistent oil sump temperatures. Advantages The system is very simple. The method of determining the oil level is more accurate than the dipstick method
32、. The results should be more accurate than the dipstick method. This is not as operator dependent as the dipstick method. However is still affected by drain back and temperature. Disadvantages The system takes a long test time to get accurate results. The accuracy will be improved with longer test d
33、uration. However the time duration may be less that the time required by the dip stick method. Inconsistent drain back of oil in the engine can cause erroneous results. Inconsistent oil sump temperatures may result in errors. Oil leaks from the engine will be measured as oil consumption unless exter
34、nal leakage is quantified and subtracted from gross consumption. Fuel or coolant dilution in the oil will influence the measured level of oil consumption. Extended duration of operation required to get a reading makes it difficult to study break-in effects. SAE J2796 Issued FEB2007 - 5 - 5.3 Drain a
35、nd Weigh System The drain and weigh system has been used as a relatively simple system to determine oil consumption. A known amount of oil is added to the engine, and the engine is run for a specified length of time. The oil in the engine must be drained precisely and consistently from the engine an
36、d weighed. The difference in oil weight before and after test is the amount of oil consumed. Notes Before establishing the initial oil weight for this type of test, the engine should be run first to fill the filters and passages with oil. Otherwise there will be a false first oil consumption measure
37、ment reading. Internal drain back of oil within the engine to the sump can significantly affect this measurement. Drain back time and position of the engine crank may affect this. Drain temperature and time when removing the oil from the engine can affect the measurement. If multiple measurements ar
38、e made, be very careful not to spill the oil. The installation angle of the engine may affect how the oil drains within the engine and as it is drained out of the engine. Advantages The system is very simple and inexpensive. Disadvantages The system takes a long test time to get accurate results. Th
39、e results are dependent on how consistently the oil drains from the engine. Oil leaks from the engine will be measured as oil consumption. This method is susceptible to the operator spilling oil which will give erroneous measurements. Fuel or coolant dilution in the oil will influence the measured l
40、evel of oil consumption. Extended duration of operation required to get a reading makes it difficult to study break-in effects. Some of the disadvantages described above are being eliminated by automatic drain and weigh systems. For example, a system can be designed to pump the oil from the oil sump
41、 into a measurement tank. This can be done from the oil drain plug or the dipstick. This will reduce the time for the “drain”. Also, the full sump does not need to be pumped out which might increase the accuracy of the measurement. By having a hard wired pump to the engine, the chances of operator s
42、pillage is less. It might be possible to do this during engine operation which might minimize the internal drain back variability. SAE J2796 Issued FEB2007 - 6 - FIGURE 1 - EXAMPLE OF AN AUTOMATED DRAIN AND WEIGH SYSTEM 5.4 Calibrated Loss Measurement The amount of oil lost can be calibrated to the
43、oil level in the oil pan. Therefore oil is put in the engine in increments. The oil level is recorded with the corresponding amount of oil in the oil pan. Therefore, when the oil level decreases due to oil consumption, the amount of oil lost can be directly related to the oil level in the oil pan. I
44、n one common application, a capacitance sensor is proposed to determine the oil level. However other techniques may be used to measure the oil level such as pressure sensors in the oil pan or other oil height measurement systems. See Figure 2. Head Engine Crank Shaft Capacitance SensorEqualizationTu
45、beCommunicating Vessel HeadEngineCrank ShaftPressure Sensor Direct MeasurementFIGURE 2 - OIL LEVEL MEASUREMENT SYSTEMS SAE J2796 Issued FEB2007 - 7 - Notes Oil sump temperatures can significantly affect this type of measurement. Measurements should be made at consistent oil sump temperatures. Advant
46、ages The system is simple in concept. Disadvantages The accuracy of the method is subject to calibration accuracy. The method is subject to variations in oil level due to inconsistent oil drain-back within the engine. Fuel and coolant dilution in the oil will influence the measured level of oil cons
47、umption. 6. CONSTANT LEVEL MEASUREMENT METHODS 6.1 Common Level System In the common level system, the oil levels in the engine and the oil measurement device are the same. This is accomplished by having a tube that connects the oil measurement device to the oil pan of the engine that allows oil to
48、move back and forth between the engine and the measurement device. The equalization or vent tube maintains the same pressure above the oil in both the engine and the oil cart. A schematic diagram of this device is shown in Figure 1. As the engine consumes oil, the oil level will drop. The oil level
49、should drop in both the engine and the oil vessel at the same rate. When the oil level decreases, the measurement device detects the change in level, and initiates a flow of oil back into the engine to replenish and bring the oil level back to the original level. The amount of oil that put back into the engine is recorded as
