Vehicle model.
Vehicle model. Calculate the simulated vehicle reference speed, refi, using the GEM HIL model's vehicle submodel or the equations in this paragraph (f)(3):
(4) Example. The following example illustrates a calculation of fnref,dyno using paragraph (f)(1) of this section where torque is measured at the axle input shaft. This example is for a vocational Light HDV or vocational Medium HDV with 6 speed automatic transmission at B speed (test 4 in table 1 to paragraph (h)(2)(ii) of this section).
(g) Driver model. Use the GEM HIL model's driver submodel or design a driver model to simulate a human driver modulating the throttle and brake pedals. In either case, tune the model to follow the test cycle as closely as possible meeting the following specifications:
(1) The driver model must meet the following speed requirements:
(i) For operation over the highway cruise cycles, the speed requirements described in 40 CFR 1066.425(b) and (c).
(ii) For operation over the Heavy-Duty Transient Test Cycle specified in 40 CFR part 1037, appendix A, the SET as defined § 1036.510, the Federal Test Procedure (FTP) as defined in § 1036.512, and the Low Load Cycle (LLC) as defined in § 1036.514, the speed requirements described in 40 CFR 1066.425(b) and (c).
(iii) The exceptions in 40 CFR 1066.425(b)(4) apply to the highway cruise cycles, the Heavy-Duty Transient Test Cycle specified in 40 CFR part 1037, appendix A, SET, FTP, and LLC.
(iv) If the speeds do not conform to these criteria, the test is not valid and must be repeated.
(2) Send a brake signal when operator demand is zero and vehicle speed is greater than the reference vehicle speed from the test cycle. Include a delay before changing the brake signal to prevent dithering, consistent with good engineering judgment.
(3) Allow braking only if operator demand is zero.
(4) Compensate for the distance driven over the duty cycle over the course of the test. Use the following equation to perform the compensation in real time to determine your time in the cycle:
(h) Vehicle configurations to evaluate for generating fuel maps as defined in § 1036.505. Configure the driveline and vehicle models from paragraph (f) of this section in the test cell to test the powertrain. Simulate multiple vehicle configurations that represent the range of intended vehicle applications using one of the following options:
(1) For known vehicle configurations, use at least three equally spaced axle ratios or tire sizes and three different road loads (nine configurations), or at least four equally spaced axle ratios or tire sizes and two different road loads (eight configurations). Select axle ratios to represent the full range of expected vehicle installations. Select axle ratios and tire sizes such that the ratio of engine speed to vehicle speed covers the range of ratios of minimum and maximum engine speed to vehicle speed when the transmission is in top gear for the vehicles in which the powertrain will be installed. Note that you do not have to use the same axle ratios and tire sizes for each GEM regulatory subcategory. You may determine appropriate Crr, CdA, and mass values to cover the range of intended vehicle applications or you may use the Crr,CdA, and mass values specified in paragraph (h)(2) of this section.
(2) If vehicle configurations are not known, determine the vehicle model inputs for a set of vehicle configurations as described in § 1036.540(c)(3) with the following exceptions:
(i) In the equations of § 1036.540(c)(3)(i), ktopgear is the actual top gear ratio of the powertrain instead of the transmission gear ratio in the highest available gear given in table 1 to paragraph (c)(2) of § 1036.540.
(ii) Test at least eight different vehicle configurations for powertrains that will be installed in Spark-ignition HDE, vocational Light HDV, and vocational Medium HDV using the following table instead of table 2 to paragraph (c)(3)(ii) of § 1036.540:
(iii) Select and test vehicle configurations as described in § 1036.540(c)(3)(iii) for powertrains that will be installed in vocational Heavy HDV and tractors using the following tables instead of tables 3 and 4 to paragraph (c)(3)(iii) of § 1036.540:
(3) For hybrid powertrain systems where the transmission will be simulated, use the transmission parameters defined in § 1036.540(c)(2) to determine transmission type and gear ratio. Use a fixed transmission efficiency of 0.95. The GEM HIL transmission model uses a transmission parameter file for each test that includes the transmission type, gear ratios, lockup gear, torque limit per gear from § 1036.540(c)(2), and the values from § 1036.505(b)(4) and (c).
(i) [Reserved]
(j) Duty cycles to evaluate. Operate the powertrain over each of the duty cycles specified in 40 CFR 1037.510(a)(2), and for each applicable vehicle configuration from paragraph (h) of this section. Determine cycle-average powertrain fuel maps by testing the powertrain using the procedures in § 1036.540(d) with the following exceptions:
(1) Understand “engine” to mean “powertrain”.
(2) Warm up the powertrain as described in § 1036.520(d).
(3) Within 90 seconds after concluding the warm-up, start the transition to the preconditioning cycle as described in paragraph (j)(5) of this section.
(4) For plug-in hybrid engines, precondition the battery and then complete all back-to-back tests for each vehicle configuration according to 40 CFR 1066.501(a)(3) before moving to the next vehicle configuration. The following figure illustrates a charge-depleting test sequence with engine operation during two duty cycles, which are used for criteria pollutant determination:
(5) If the preceding duty cycle does not end at 0 mi/hr, transition between duty cycles by decelerating at a rate of 2 mi/hr/s at 0% grade until the vehicle reaches zero speed. Shut off the powertrain. Prepare the powertrain and test cell for the next duty-cycle.
(6) Start the next duty-cycle within 60 to 180 seconds after shutting off the powertrain.
(i) To start the next duty-cycle, for hybrid powertrains, key on the vehicle and then start the duty-cycle. For conventional powertrains key on the vehicle, start the engine, wait for the engine to stabilize at idle speed, and then start the duty-cycle.
(ii) If the duty-cycle does not start at 0 mi/hr, transition to the next duty cycle by accelerating at a target rate of 1 mi/hr/s at 0% grade. Stabilize for 10 seconds at the initial duty cycle conditions and start the duty-cycle.
(7) Calculate cycle work using GEM or the speed and torque from the driveline and vehicle models from paragraph (f) of this section to determine the sequence of duty cycles.
(8) Calculate the mass of fuel consumed for idle duty cycles as described in paragraph (n) of this section.
(k) Measuring NOXemissions. Measure NOX emissions for each sampling period in grams. You may perform these measurements using a NOX emission-measurement system that meets the requirements of 40 CFR part 1065, subpart J. If a system malfunction prevents you from measuring NOX emissions during a test under this section but the test otherwise gives valid results, you may consider this a valid test and omit the NOX emission measurements; however, we may require you to repeat the test if we determine that you inappropriately voided the test with respect to NOX emission measurement.
(l) [Reserved]
(m) Measured output speed validation. For each test point, validate the measured output speed with the corresponding reference values. If speed is measured at more than one location, the measurements at each location must meet validation requirements. If the range of reference speed is less than 10 percent of the mean reference speed, you need to meet only the standard error of the estimate in table 4 to this paragraph (m). You may delete points when the vehicle is stopped. If your speed measurement is not at the location of ƒnref, correct your measured speed using the constant speed ratio between the two locations. Apply cycle-validation criteria for each separate transient or highway cruise cycle based on the following parameters: