Fuel Injector Performance Test. Shirley Echeverria

Transcription

1 Fuel Injector Performance Test Shirley Echeverria

2 Why Fuel Injector Performance Test (IPT) is needed? Presently Lack Robust In-Shop Injector Evaluations High Pressure Key Off Leak Down Can Be Used For Cracked Check Ball or Severely Damaged Seat Cylinder Cut Out Is A Weak Test The test potentially offer advantage to The Customer (Repeat Returns To Shop, $$$) The Dealer (Reduces Guesswork)

3 IPT Benefits IPT Permits Technician To Test Each Injector Typical Failures Detected: Injector: Long On Times : Main QTY is Low or High (Plugged Nozzle, etc.) Affects DPF Performance Long Before Other Symptoms or Methods Can Be Employed Injector: Short On Times Pilot Drift High or Low (Pilot Valve Effects, Ball/Seat, Beat-in) Affects Idle Quality and/or After-treatment Performance System: All the injectors test OK 3 Cummins Confidential Restricted

4 What is IPT? The Injector Performance Test (IPT) is a diagnostic test that runs through INSITE. The algorithm gathers pressure drop measurements of HPCR type injectors at different fuel quantity and pressure using a cycle of overrides. The measures are compared against calibrated thresholds to diagnose each injector individually.

5 5 Cummins Confidential Restricted How Does IPT work? Test Begins IF CONDITIONS ARE MET Engine RPM Is Increased To Desired test speed Rail Pressure Is Stabilized At desired test pressure All Injections Are Disabled (0 Fueling) The IMV Is Closed (Fuel Pressure = Constant) Engine Decels Test Cycle (n Test Cycles Per Test Point) Injector Is Fired Combustion Cycles Pressure Drop is The Sum of the Combustion Cycles IPT Result Is The Average Of n Test Cycles INSITE Compares Raw Data To C_IPT_hp_LowDeltaPLimit and C_IPT_hp_HighDeltaPLimit. In Range = Pass Out of Range = Fail IPT Result Is Stored In Array. IPT_HP_TestCylDeltaP[x]

6 Engine Speed (rpm) Rail Pressure (Bar) IPT Cycle Data Injector Performance Test Cycle Example - 100mg Check Start Cycle Pressure Sample 1 dp 1 dp 2 dp 3 dp combustion cycles 1 pulses per cycle Pressure Sample 2 100mg/pulse 400mg total Time (sec) combustion cycle Measured Pressure Pressure Command Averaged Pressure drop = [Sum( dp 1 +dp 2 +dp 3 +dp 4 ) 1 + Sum ( dp 1 +dp 2 +dp 3 +dp 4 ) 2 + Sum(dP 1 +dp 2 +dp 3 +dp 4 ) n ] / n n = Test Cycle Engine Speed dp = pressure drop for each combustion cycle n = number of Test cycles Time (sec)

7 Test Abort Conditions The algorithm looks for external errors and engine enable conditions before flagging that it is ok to start the test External errors that prevent the test to run include Fuel system errors Rail pressure sensor Engine position and speed sensing system Injector driver circuits Rail pressure control system Other abort conditions are: Coolant Temperature < 70 degc 7 9/25/2014 Cummins Confidential

8 Test Abort Conditions (cntd.) Acceleration pedal is pressed Leakage rate is more than allowed threshold limit Rail pressure instability is more than allowed threshold limit Fuel System Self pumping Engine speed is <500 or >1800 MCA Status PTO is active (unless used as primary throttle) Parking Brake is not set Engine Brake is turned on Gear is engaged Vehicle speed sensor >0 Brake Switch is pressed Clutch Switch is pressed Engine Protection flag is set Fan driver errors

9 Prohibit / Abort Conditions Summary 9 Cummins Confidential Restricted

10 IPT in Off-Highway Currently IPT has been developed and validated for use in QSX and QSL platforms Can Be Triggered By Technician Using A Service Tool (INSITE) Performed in Parking Lot (Stationary Test) Lasts About 10 Minutes INSITE displays Pass / Fail Results Displayed Live On INSITE Screen External File Includes: Raw IPT Data Bucket 1 and Bucket 2 ICC Data 10 Cummins Confidential Restricted

11 Off Highway Strategy Summary Purpose of IPT: Provide On Site Evaluation Information For The Mechanic 2014 Midrange Clydesdale: Heavy Duty IPT: 4 Points? : (Pass / Fail / Not Converged) - QSL does not use Fueling Compensation in any fueling region External File: - 4 test points are used for IPT -Raw IPT dp Data - IPT Convergence Table - Filtered Residuals - 96 Coefficients (IFM) Atlantic Red: (QSX) Closed Loop: IFM (low) and AIC (mid and high) IPT: - 2 QSX Points : use Fueling (Pass / Compensation Fail / Not Converged) in mid and high fueling region External - 2 test File: points are used for IPT -Raw IPT dp Data -IPT Convergence Table -Filtered Residuals -96 Coefficients (Low: IFM / Mid High: AIC) 11 Avoiding a Scenario Where An Injector Test Is Run And The Result Is FAIL But We Haven t Converged (Example: ECM Bricked ). Cummins Confidential Restricted

12 Who can enable IPT feature? Start Is Is the Calibration calibration Generic Yes Disable IPT No Does the Application have Does the Application have High Parasitic Loads High Parasitic Loads 50% at LSI = Too high (For QSX 15) 25% at LSI = Too high (For QSL 9) Yes If Parasitic loads are too high, Can load be easily disconnected No Disable IPT No Yes No Disable IPT Yes Is application required to run at set speeds i.e. genset or similar? Yes Is Is application sensitive Sensitive to rapid engine Engine speed changes changes Yes What is load reduced to? Does it make it below high parasitic criteria? No No Is application sensitive to rapid speed change? i.e. compressor required to slowly change speed Yes Disable IPT No Enable IPT

13 IPT in Off Highway Generic Calibrations will have feature turned off Feature can be requested through Powermatch once approved AEB Attachment L have procedure available for testing AEB includes description of the feature INSITE functionality works properly for tests with 2-4 points. INSITE version from 8.0

14 Field test units: QSL Engine_Speed APC_hp_fdbk APC_hp_cmd Total_fueling Residual

15 Field test unit: QSX Engine_Speed APC_hp_Fdbk APC_hp_Cmd Total_fueling Residual

16 Running the Test Test procedure is specified in AEB Attachment L

17 INSITE Screen Results reports failure for each injector Status informs status of the test or reason for abort

18 IPT Output File Engine info Barcode info Test points specification Delta-P measured for each injector on each test point

19 Questions The IPT benefits include a. Reduced cost at dealer (less guesswork) b. Customer benefit (reduced returns to shop) c. Identify individual failure injector d. All of above True/false Following conditions will prevent IPT for starting Coolant Temperature low Acceleration pedal is pressed Engine speed is too low or too high PTO is active