TORSIONAL VIBRATION SOLUTIONS FOR CYLINDER DEACTIVATION

Abstract

A method for operating a 6-cylinder engine connected to a driveline including a transmission. The method includes: monitoring a rotational speed of a crankshaft of the 6-cylinder engine: monitoring a gear selection of the transmission; and operating the 6-cylinder engine in one of Order 3, Order 1.5 or Order 1 based on whether the selected Order avoids operating the 6-cylinder engine at a critical speed that corresponds to a natural harmonic frequency of the driveline, wherein priority is given to operating in Order 1.5, Order 1 then Order 3, in that order.

Claims

1. A method of operating a 6-cylinder engine connected to a driveline, the method comprising: monitoring a rotational speed of a crankshaft of the 6-cylinder engine; monitoring a gear selection of a transmission of the driveline; and when the transmission is in gears 1 through 5, selectively operating the 6-cylinder engine in Order 1.5 when the speed of crankshaft is less than 1160 RPM and operating the 6-cylinder engine in Order 1 when the speed of crankshaft is less than 1720 RPM.

2-6. (canceled)

7. A method for operating a 6-cylinder engine connected to a driveline, the method comprising: monitoring a rotational speed of a crankshaft of the 6-cylinder engine; monitoring a gear of a transmission of the driveline; and selectively operating the 6-cylinder engine in one of Order 3, Order 1.5 or Order 1 based on the following criteria in the following order: first, operating the 6-cylinder engine in Order 1.5 if the rotational speed of the crankshaft is not within a predetermined differential speed of a critical speed of the crankshaft for the engine in Order 1.5 for the gear of the transmission, wherein the critical speed causes the driveline to vibrate at a natural harmonic frequency of the driveline, second, operating the 6-cylinder engine in Order 1 if the rotational speed of the crankshaft is not within a predetermined differential speed of a critical speed of the crankshaft for the engine in Order 1 for the gear of the transmission, wherein the critical speed in the gear causes the driveline to vibrate at a natural harmonic frequency of the driveline, else, operating the 6-cylinder engine in Order 3.

8. The method of claim 7, wherein operating in Order 1 prioritizes firing 2 cylinders over firing 4 cylinders.

9. The method of claim 7, wherein the predetermined differential speed is 200 revolutions per minute.

10. The method of claim 7, wherein the predetermined differential speed is 150 revolutions per minute.

11. The method of claim 7, wherein the transmission has 12 gears.

12. The method of claim 7, wherein the transmission has 18 gears.

13. The method of claim 7, wherein the transmission is provided on a vehicle with a 62 or a 64 configuration.

14. (canceled)

15. The method of claim 7, wherein the transmission is provided on a vehicle with a 86 configuration.

16. The method of claim 7, wherein the natural harmonic frequency of the driveline corresponds to a torsional vibration of the driveline.

17. A method for operating a 6-cylinder engine connected to a driveline including a transmission, the method comprising: monitoring a rotational speed of a crankshaft of the 6-cylinder engine; monitoring a gear selection of the transmission; and operating the 6-cylinder engine in one of Order 3, Order 1.5 or Order 1 based on whether the selected Order avoids operating the 6-cylinder engine at a critical speed that corresponds to a natural harmonic frequency of the driveline, wherein priority is given to operating in Order 1.5, Order 1 then Order 3, in that order.

18. The method of claim 17, wherein operating in Order 1 prioritizes firing 2 cylinders over firing 4 cylinders.

19. The method of claim 17, wherein the transmission has 12 gears.

20. The method of claim 17, wherein the transmission has 18 gears.

21. The method of claim 17, wherein the transmission is provided on a vehicle with a 62 or a 64 configuration.

22. (canceled)

23. The method of claim 17, wherein the transmission is provided on a vehicle with a 86 configuration.

24. The method of claim 17, wherein the natural harmonic frequency of the driveline corresponds to a torsional vibration of the driveline.

25. A non-transitory computer-readable storage medium storing a computer program comprising instructions that, when the program is executed by a computer or a controller, cause the computer to implement the method of claim 1.

26. A non-transitory computer-readable storage medium storing a computer program comprising instructions that, when the program is executed by a computer or a controller, cause the computer to implement the method of claim 7.

27. A non-transitory computer-readable storage medium storing a computer program comprising instructions that, when the program is executed by a computer or a controller, cause the computer to implement the method of claim 17.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is a schematic illustrating aspects of a vehicle NVH transmission pathway;

[0029] FIG. 2 is a schematic of control electronics;

[0030] FIGS. 3A-3C are illustrations of CDA configurations in 6-cylinder in-line engines;

[0031] FIGS. 4A-4B are cylinder firing and cylinder deactivation combinations illustrative of periodic information in a 6 cylinder engine;

[0032] FIGS. 5A-8B are graphical illustrations of data collected from engine sweeps; and

[0033] FIG. 9 is a flowchart of a CDA mode selection program.

DETAILED DESCRIPTION

[0034] FIG. 1 shows a simplified illustration of a vehicle 10. The vehicle 10 includes an engine 100 outputting power via a crankshaft 110 to a flywheel 120. The clutch 200 is shown open and connected to the input shaft of the transmission 300. Drive axles and a driveshaft 400 are shown connected to wheels 500. The clutch 200, transmission 300, drive axles and driveshaft 400 are referred to as the driveline. A driver seat 700 experiences noise, vibration, and harshness (NVH) from many aspects of the vehicle 10. Many aspects of the vehicle 10 are omitted to simplify the drawings, but such aspects can be included and are not limited to differentials, power take-off (PTO), brake system, supercharger, cooling systems, battery systems, among many other aspects. The powertrain comprises the minimum components of FIG. 1 to convey motive power from the engine 100 (power source) to the wheels 500. The clutch 200 is shown disconnected from the flywheel 200 (clutch 200 is open). The components downstream from the flywheel 200 can collectively be referred to as the drivetrain. The drivetrain resonance can be collectively summed and the natural frequency of the drivetrain can be measured at the coupling between the flywheel 200 and the downstream devices of the drivetrain. Realizing that the drivetrain natural frequency can be summed in this way has not been obvious to others in the art for purposes of determining the cylinder deactivation (CDA) mode of engine operation.

[0035] The vehicle 10 can experience NVH as a result of two primary sources, linear vibration and torsional vibration of the engine 100. The linear vibration of the engine 100 may be measured in an x, y and z direction at the engine mounts M1, M2, M3. Conversely, the torsional vibration of the engine 100 is an angular measurement that may be measured at engine couplings (not shown) or the driveshaft 400.

[0036] Turning to FIG. 2, a schematic of control electronics is shown. Engine mounts, namely front engine mount M1 and left and right rear engine mounts M2, M3, can be placed in locations to stabilize the roll and pitch of the engine. Sensors, such as accelerometers, can be integrated with the engine mounts M1, M2, M3 to monitor the roll and pitch of the engine and can monitor engine mount behavior. One or more engine sensor 101 can monitor engine activity such as valvetrain activity, fueling, piston motion, crankshaft RPMs, among other data. A clutch sensor 201 can monitor the open, close, or slip positions of the clutch 200. One or more transmission sensor 301 can monitor the gear selection, neutral position, operating conditions, among other aspects of transmission operation. One or more drivetrain sensor 401 can monitor the axles, wheels, brakes, and other chassis activity, for example.

[0037] Each of the sensors 101, 201, 301, 401 can feed vehicle data collected from the vehicle 10 to one or more on-board or networked computing devices. An electronic control unit (ECU) 1000 in this example is on-board, though it can be networked with so called cloud computing, including GPS or other location services, fleet management applications, among others. Each of the sensors can be bi-directional and receive commands from the ECU 1000 and so the sensors 101, 201, 301, 401 can also comprise an affiliated or integrated actuator.

[0038] Example actuations can comprise adjusting the engine mounts M1, M2, M3, directing valvetrain or fuel injection, implementing fail-safes, opening or closing the clutch, changing transmission gear or selecting a neutral position, opening or closing a differential, PTO, brake caliper, wheel hub, among others. Numerous manifestations of valvetrains can be used with the disclosure, and the engine sensor 101 is representative of the myriad combination of control devices that can be actuated to implement combustion, fueling, and cylinder deactivation, among other techniques such as engine braking, early or late valve opening or closing strategies, among others.

[0039] The collected vehicle data can be stored in a memory device 1001, which can comprise a data storage section 1010 and an algorithm storage section 1012, for example. A processor-executable control algorithm stored in a memory device can be configured for operating an engine in a cylinder deactivation (CDA) mode comprising any of the methods disclosed herein.

[0040] One or more processing devices can be included to process the stored data and the stored algorithms. Processor 1002 comprises in the example an NVH controller 1020 that can process data and output other vehicle commands to the actuators integrated or affiliated with the sensors. The other vehicle commands can, for example, mitigate NVH to the seat 700 and steering wheel 600 of the vehicle 10. For example, a damping system can be activated, a driveline component can be adjusted, or an accessory or other vehicle system can be adjusted, among others. Only so much of the vehicle NVH can be ameliorated by the other vehicle commands. The engine 100 itself can be a contributor to the NVH, and so a CDA controller 1022 can implement cylinder selections on the valvetrain of the engine 100 to operate the vehicle 10 within NVH thresholds, as described in more detail hereinbelow. The CDA controller 1022 may include numerous hardware configurations, including sub processors, networked computing devices, among others. The operation mode of the vehicle 10 can be processed using the control algorithms and CDA modes can be selected, or all-cylinder firing modes can be selected, and various cylinder activation techniques can be implemented, as discussed in detail hereinbelow.

[0041] Combinations of variable valve actuation (VVA) hardware on a valvetrain can enable an engine to switch between operating modes. Capsules, latches, rocker arms, roller lifters, switching roller finger followers, cams, solenoids, oil control valves, among others can be used with the engine 100 to open and close intake and exhaust valves paired with cylinders 1-6. The cylinders can include a single intake valve or pairs of intake valves per cylinder, likewise, single exhaust valve or pairs of exhaust valves per cylinder 1-6. FIGS. 3A-3B illustrate example cylinder variations for cylinder deactivation modes and the VVA hardware can be configured to implement the fired Valve Active or deactivated Valve Inactive cylinder combinations. CDA modes can include engine operation where intake and exhaust valves are closed and fuel is shut off while a piston reciprocates in an engine cylinder. The CDA modes disclosed herein can include low pressure charge trapping, also known as residual exhaust gas CDA. High pressure charge trapping is not excluded, nor are techniques topping off cylinder pressures with fuel injections or cylinder burps.

[0042] FIG. 3A illustrates different cylinder combinations that can occur when four cylinders are deactivated in a cylinder deactivation mode while two cylinders are fired in a cylinder firing (CF) mode, i.e., 4CDA or 2CF. FIG. 3B illustrates different cylinder combinations that can occur when three cylinders are deactivated while two cylinders are fired, i.e., 3CDA or 3CF. FIG. 3C illustrates cylinder combinations that can occur when two cylinders are deactivated in a cylinder deactivation mode while four cylinders are fired in a cylinder firing mode, i.e., 2CDA or 4CF.

[0043] There is an equivalence between cylinder deactivation modes, such that NVH in an in-line engine can switch between which cylinders are in firing mode and which cylinders are in CDA mode. As recognized, the NVH for having cylinders 1-3 active in cylinder firing mode and cylinders 4-6 deactivated in CDA mode is the same as having cylinders 4-6 in cylinder firing mode and cylinders 1-3 in CDA mode. Also, the NVH response has equivalence when cylinders are as indicated in FIG. 3A (cylinders 1 & 6, cylinders 3 & 4, and cylinders 2 & 5 in cylinder firing mode while the remainder are in CDA mode). Likewise, FIG. 3C has NVH equivalence among the 2CDA or 4CF modes illustrated. This provides a valuable diesel engine system.

[0044] It is contemplated that instead of costly VVA on each of the cylinders of the valvetrain, an option that is certainly beneficial and contemplated as an embodiment of this disclosure, a diesel engine system can comprise CDA hardware on less then all of the cylinders of the valvetrain. One or two or more cylinders can be provided with a basic set of hardware, or an engine braking set of hardware, for example, while other cylinders provide the CDA modes disclosed herein

[0045] It is also contemplated that implementing multi-cylinder cylinder deactivation modes in a functioning 6-cylinder engine can include switching between equivalent two-cylinder CF modes (FIG. 3A), wherein cylinders 1 & 6 of the 6-cylinder engine are switched between cylinders 2 & 5 of the 6-cylinder engine or are switched between cylinders 3 & 4 of the 6-cylinder engine for the cylinder firing modes. The remaining cylinders (respectively 2-5; 1, 3, 4, & 6; and 1, 2, 5, & 6) can be correspondingly switched in CDA modes.

[0046] It is contemplated that implementing multi-cylinder cylinder deactivation modes in a functioning 6-cylinder engine can include switching between equivalent three-cylinder CF modes (FIG. 3B), wherein cylinders 1-3 of the 6-cylinder engine firing are switched between cylinders 4-6 of the 6-cylinder engine firing.

[0047] Further, it is contemplated that implementing multi-cylinder cylinder deactivation modes in a functioning 6-cylinder engine can include switching between equivalent four-CF modes (FIG. 3C), wherein cylinders 1, 3, 4, & 6 of the 6-cylinder engine can be switched in CF mode between cylinders 1, 2, 5, & 6 of the 6-cylinder engine firing. The remaining cylinders (respectively 2 & 5 and 3 & 4) can be correspondingly switched in CDA modes.

[0048] The CDA modes can be characterized by forcing functions, also known as periodic orders. The periodic orders are summarized for various combinations of cylinders deactivated and cylinders firing in FIGS. 4A and 4B, showing 6-cylinder engine combinations. The periodic orders and cylinder combinations are compared to baseline all-cylinders firing 6 CF mode. Firing periods are denoted for cylinders firing, and these firing periods are correlated to the engine revolutions to arrive at the periodic orders. The periodic orders can be correlated to the resonant frequencies to operate in and to avoid. The modal alignment map can be structured to permit the processor to select CDA modes with acceptable effective frequencies while avoiding resonant frequencies. These configurations are further illustrated in FIGS. 3A-3C, which show different arrangements of 2CF, 3 CF and 4 CF modes applied to a 6-cylinder inline engine.

[0049] Equations for calculating the correlations between the firing orders, the periodic orders, and the effective frequency of the CDA modes can be as in the following examples:

4 Cylinders Firing @ 1000 rpm

Example 1

[0050] Number of Cylinders Fired Per Revolution (Firing Order)=2

[00001]$f_{\mathrm{firing}}=\frac{\mathrm{rpm}}{60s/\min }*\frac{\#\mathrm{Cyl}\mathrm{fired}}{\mathrm{rev}}=\frac{1000\mathrm{rpm}}{60s/\min }*1=33.3\mathrm{Hz}$

Example 2

[0051] Number of Periods Per Revolution (Periodic Order)=1

[00002]$f_{\mathrm{periodic}}=\frac{\mathrm{rpm}}{60s/\min }*\frac{\#\mathrm{periods}}{\mathrm{rev}}=\frac{1000\mathrm{rpm}}{60s/\min }*1=16.7\mathrm{Hz}$

Example 3

[0052] Number of Cylinders Fired Per Revolution (Firing Order)=1

[00003]$f_{\mathrm{firing}}=\frac{\mathrm{rpm}}{60s/\min }*\frac{\#\mathrm{Cyl}\mathrm{fired}}{\mathrm{rev}}=\frac{1000\mathrm{rpm}}{60s/\min }*1=16.7\mathrm{Hz}$

Example 4

[0053] Number of Periods Per Revolution (Periodic Order)=1

[00004]$f_{\mathrm{periodic}}=\frac{\mathrm{rpm}}{60s/\min }*\frac{\#\mathrm{periods}}{\mathrm{rev}}=\frac{1000\mathrm{rpm}}{60s/\min }*1=16.7\mathrm{Hz}$

[0054] In order to simplify the implementation of cylinder deactivation modes and address a market-adoption hurdle, the methods herein can comprise monitoring an engine load. Built into the method is a calibratable delineation of engine load.

[0055] The brake mean effective pressure (BMEP) provides a standardization for the engine so that the methods herein can be scaled to other engine sizes. Thus, the disclosure is not limited to 3 bar BMEP. In some instances, the CDA mode limit can be reached at, for example, 2 bar BMEP or 4 bar BMEP, among others, including fractions thereof.

[0056] Previous methods focused on reducing the NVH experienced by an operator by focusing on linear vibration and tuning the engine mounts M1, M2, M3 to reduce the NVH experienced by the operator during operation of the various CDA modes. The inventors found that consideration should also be given to the NVH experienced by the driveline (i.e., the clutch 200, the transmission 300, the drive axles and driveshaft 400). If the NVH experienced by the driveline is not taken into consideration, undesired noise may be experienced. The inventors found that if the engine speed and gear selection is known, it is possible to select the proper CDA mode to avoid the driveline experiencing excessive NVH.

[0057] The present method is explained in detail below. The inventors found that, for each gear (Gi) (where i=1, 2, . . . n, where n=total number of gears), each of Order 1.5 and Order 1 has a critical engine speed (S2.sub.ij, S3.sub.ij) (where S2 is for the 2.sup.nd mode, S3 is for 3.sup.rd mode, i=1, 2, . . . n, where n=total number of gears and j=1, 1.5 for Order 1 and Order 1.5) at which the torsional vibration of the driveline will be at a natural harmonic frequency and cause excessive NVH. In other words, the critical speeds represent, for a given Order (1.5 or 1), the engine speeds to be avoided when the transmission 300 is in the given gear Gi. For Order 3, i.e., all cylinders firing, the driveline is designed to handle the natural harmonic frequencies generated at the critical engine speed so no action is required by the electronic control unit 1000 when the engine 100 is in Order 3.

[0058] Data was collected for torsional vibration of the driveline in the 2.sup.nd mode and the 3.sup.rd mode. The inventors found that torsional vibration in the 2.sup.nd mode contributed more to NVH, as compared to torsional vibration in the 3.sup.rd mode. Accordingly, consideration is given below to torsional vibration in the 2.sup.nd mode although data is also provided for torsional vibration in the 3.sup.rd mode.

[0059] Critical speed, gear selection and order data was collected for a 6-cylinder diesel engine connected to an Eaton Cummins Automated Transmission Technologies Model 1 (also referred as ENDURANT) and Model 2 transmissions for land vehicles, and more specifically, for vehicles with a 62, 64, or 68 configuration. The data collected is provided in TABLES 1-4 and FIGS. 5A-8B. In FIGS. 5A-8B, the error bars represent the critical speeds +/200 RPM.

TABLE-US-00001 TABLE 1 MODEL 1 6 2 (FIGS. 5A and 5B) 2.sup.nd Mode 3.sup.rd Mode Order Order Order Order Order Order Gear 3 Engine 1.5 Engine 1 Engine 3 Engine 1.5 Engine 1 Engine Engage Gear 2.sup.nd 3.sup.rd Speed (RPM) Speed (RPM) Speed (RPM) Speed (RPM) Speed (RPM) Speed (RPM) (G.sub.i) Ratio Mode Mode (S2.sub.i, 3) (S2.sub.i, 1.5) (S2.sub.i, 1) (S3.sub.i, 3) (S3.sub.i, 1.5) (S3.sub.i, 1) 1 14.43 56.6 73.1 1132 2264 3395 1462 2925 4387 2 11.05 47.0 72.7 940 1881 2821 1454 2908 4362 3 8.44 53.6 75.1 1073 2145 3218 1502 3004 4506 4 6.46 44.8 74.5 897 1794 2690 1489 2979 4468 5 4.95 48.1 77.1 963 1926 2888 1541 3082 4623 6 3.79 40.2 77.6 803 1607 2410 1552 3104 4656 7 2.91 42.9 84.5 859 1718 2576 1689 3379 5068 8 2.23 37.0 83.9 741 1481 2222 1678 3356 5034 9 1.70 35.4 91.3 709 1418 2127 1825 3651 5476 10 1.30 31.6 91.1 632 1264 1896 1822 3645 5467 11 1.00 30.4 96.0 608 1216 1824 1920 3840 5760 12 0.77 27.9 96.0 559 1117 1676 1919 3838 5758

TABLE-US-00002 TABLE 2 MODEL 1 6 4 (FIGS. 6A and 6B) 2.sup.nd Mode 3.sup.rd Mode Order Order Order Order Order Order Gear 3 Engine 1.5 Engine 1 Engine 3 Engine 1.5 Engine 1 Engine Engage Gear 2.sup.nd 3.sup.rd Speed (RPM) Speed (RPM) Speed (RPM) Speed (RPM) Speed (RPM) Speed (RPM) (G.sub.i) Ratio Mode Mode (S2.sub.i, 3) (S2.sub.i, 1.5) (S2.sub.i, 1) (S3.sub.i, 3) (S3.sub.i, 1.5) (S3.sub.i, 1) 1 14.43 48.7 58.8 973 1946 2919 1175 2350 3526 2 11.05 45.2 52.3 904 1807 2711 1046 2092 3139 3 8.44 46.9 58.9 939 1878 2816 1178 2355 3533 4 6.46 42.4 54.0 849 1697 2546 1079 2158 3237 5 4.95 43.0 58.9 860 1720 2580 1177 2354 3531 6 3.79 37.7 55.7 753 1507 2260 1114 2228 3342 7 2.91 37.9 62.6 758 1516 2274 1253 2505 3758 8 2.23 33.4 60.3 669 1338 2007 1206 2412 3618 9 1.70 31.3 63.7 626 1252 1878 1274 2547 3821 10 1.30 28.0 62.6 559 1118 1678 1253 2506 3758 11 1.00 26.5 64.3 529 1059 1588 1287 2573 3860 12 0.77 24.1 63.9 481 963 1444 1278 2555 3833

TABLE-US-00003 TABLE 3 MODEL 2 6 4 (FIGS. 7A and 7B) 2.sup.nd Mode 3.sup.rd Mode Order Order Order Order Order Order Gear 3 Engine 1.5 Engine 1 Engine 3 Engine 1.5 Engine 1 Engine Engage Gear 2.sup.nd 3.sup.rd Speed (RPM) Speed (RPM) Speed (RPM) Speed (RPM) Speed (RPM) Speed (RPM) (G.sub.i) Ratio Mode Mode (S2.sub.i, 3) (S2.sub.i, 1.5) (S2.sub.i, 1) (S3.sub.i, 3) (S3.sub.i, 1.5) (S3.sub.i, 1) 1 14.324 41 47 820 1640 2460 940 1880 2820 2 11.959 37 47 740 1480 2220 940 1880 2820 3 10.019 32 46 640 1280 1920 920 1840 2760 4 8.428 39 49 780 1560 2340 980 1960 2940 5 7.036 35 48 700 1400 2100 960 1920 2880 6 5.895 31 47 620 1240 1860 940 1880 2820 7 4.952 36 51 720 1440 2160 1020 2040 3060 8 4.135 32 50 640 1280 1920 1000 2000 3000 9 3.464 28 49 560 1120 1680 980 1960 2940 10 2.892 31 56 620 1240 1860 1120 2240 3360 11 2.415 28 55 560 1120 1680 1100 2200 3300 12 2.023 26 54 520 1040 1560 1080 2160 3240 13 1.702 26 60 520 1040 1560 1200 2400 3600 14 1.421 24 59 480 960 1440 1180 2360 3540 15 1.19 22 59 440 880 1320 1180 2360 3540 16 1 22 63 440 880 1320 1260 2520 3780 17 0.835 21 63 420 840 1260 1260 2520 3780 18 0.699 20 62 420 840 1200 1240 2480 3720

TABLE-US-00004 TABLE 4 MODEL 2 8 6 (FIGS. 8A and 8B) 2.sup.nd Mode 3.sup.rd Mode Order Order Order Order Order Order Gear 3 Engine 1.5 Engine 1 Engine 3 Engine 1.5 Engine 1 Engine Engage Gear 2.sup.nd 3.sup.rd Speed (RPM) Speed (RPM) Speed (RPM) Speed (RPM) Speed (RPM) Speed (RPM) (G.sub.i) Ratio Mode Mode (S2.sub.i, 3) (S2.sub.i, 1.5) (S2.sub.i, 1) (S3.sub.i, 3) (S3.sub.i, 1.5) (S3.sub.i, 1) 1 14.324 43 48 860 1720 2580 960 1920 2880 2 11.959 39 47 780 1560 2340 940 1880 2820 3 10.019 34 46 680 1360 2040 920 1840 2760 4 8.428 41 49 820 1640 2460 980 1960 2940 5 7.036 37 48 740 1480 2220 960 1920 2880 6 5.895 33 47 660 1320 1980 940 1880 2820 7 4.952 38 50 760 1520 2280 1000 2000 3000 8 4.135 34 49 680 1360 2040 980 1960 2940 9 3.464 30 49 600 1200 1800 980 1960 2940 10 2.892 34 53 680 1360 2040 1060 2120 3180 11 2.415 31 52 620 1240 1860 1040 2080 3120 12 2.023 28 51 560 1120 1680 1020 2040 3060 13 1.702 29 55 580 1160 1740 1100 2200 3300 14 1.421 27 55 540 1080 1620 1100 2200 3300 15 1.19 25 54 500 1000 1500 1080 2160 3240 16 1 25 56 500 1000 1500 1120 2240 3360 17 0.835 24 56 480 960 1440 1120 2240 3360 18 0.699 23 56 460 920 1380 1120 2240 3360

[0060] Referring to FIG. 9, according to the present method, the engine speed and the gear selection for the transmission are monitored by the electronic control unit 1000. The electronic control unit 1000 is program such that, based on the engine speed in a given gear (Gi), the electronic control unit 1000 selects the highest CDA mode (Order 1.5 or Order 1) for which the present engine speed is more than a predetermined differential speed away from the critical speed (S2.sub.ij). The predetermined differential speed is 150 RPM, preferably 200 RPM. When Order 1 is selected, preference is given to 2 cylinders firing over 4 cylinders firing, if 2 cylinders firing provides sufficient torque for the desired operation of the vehicle 10. If the engine speed is within plus or minus the predetermined differential speed of the critical speeds for Order 1.5 and 1, then the electronic control unit 1000 operates that engine 100 in Order 3, i.e., all cylinders firing.

[0061] As the transmission 300 shifts from one gear Gi to the next gear Gi, the electronic control unit 1000 continues to select the proper CDA mode of the engine 100 to avoid excessive NVH caused by torsional vibration in the driveline. It is also contemplated that as the speed of the engine 100 changes within a given gear (Gi), the electronic control unit 1000 is programmed to change from a first Order to a second Order in order to avoid operating the engine in the critical speed for the first Order.

[0062] Analysis of the data in TABLES 1-4 also shows that, by setting the predetermined differential speed to 200 RPM, the following Orders may be run: [0063] 1) Order 1.5 may be run in gears 1 through 5 when the engine speed is below 1160 RPM and Order 1 may be run in gears 1 through 5 when the engine speed is less than 1720 RPM; [0064] 2) Order 1 may be run in gears 1 through 9 when the engine speed is below 1480 RPM; [0065] 3) Order 1 may be run in gears 1 through 8 when the engine speed is below 1660 RPM; [0066] 4) Order 1.5 may be run in gears 1 through 7 when the engine speed is below 1040 RPM; [0067] 5) Order 1.5 may be run in gears 1-5 when the engine speed is below 1160 RPM; and [0068] 6) Order 1.5 may be run in gears 1 through 9 when the engine speed is below 920 RPM.

[0069] As described herein, the engine 100 operates on diesel fuel. It is contemplated that the present method may also be applicable to the engine 100 operating on other fuels, including but not limited to, natural gas, bio-diesel, hydrogen, gasoline or propane.

[0070] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the claimed invention.