US 4,947,329 AGrant
Method of Determining the Acceleration of a Turbine in an Automatic Transmission
Issue Date:1990-08-07
•3 Claims
•10 Drawing Sheets
Abstract
A method wherein a controller is programmed to determine the acceleration of the turbine in the torque converter to control transmission operation during a shift or gear change by counting the number of teeth during a predetermined cycle and dividing that tooth count by the actual time elapsed between the first and last tooth in an automatic transmission.
Metadata
Assignee
- Chrysler Corporation
Inventors
- Howard L. Benford
- Hemang S. Mehta
- Michael R. Lindsay
Application Information
Application Number:US 1885944
Filing Date:1988-04-29
Priority Date:1988-04-29
Art Unit:234
Classifications
IPC:
B60K 4118G01P 1500G06F 1520
Field of Search:
36474424.1;565;566866;867;862
Patent Drawings (10 sheets)
Description
BACKGROUND OF THE INVENTION
1. Field Of The Invention
The present invention relates to an automatic transmission primarily intended for motor vehicle use, and more particularly, to a method of determining the acceleration of a turbine in a torque converter of a transmission that is controlled electronically and hydraulically.
2. Description Of Related Art
Generally speaking, land vehicles require three basic components. These components comprise a power plant (such as an internal combustion engine) a power train and wheels. The internal combustion engine produces force by the conversion of the chemical energy in a liquid fuel into the mechanical energy of motion (kinetic energy). The function of the power train is to transmit this resultant force to the wheels to provide movement of the vehicle.
The power train's main component is typically referred to as the "transmission". Engine torque and speed are converted in the transmission in accordance with the tractive-power demand of the vehicle. The vehicle's transmission is also capable of controlling the direction of rotation being applied to the wheels, so that the vehicle may be driven both forward and backward.
A conventional transmission includes a hydrodynamic torque converter to transfer engine torque from the engine crankshaft to a rotatable input member of the transmission through fluid-flow forces. The transmission also includes frictional units which couple the rotating input member to one or more members of a planetary gearset. Other frictional units, typically referred to as brakes, hold members of the planetary gearset stationary during flow of power. These frictional units are usually brake clutch assemblies or band brakes. The drive clutch assemblies can couple the rotating input member of the transmission to the desired elements of the planetary gearsets, while the brakes hold elements of these gearsets stationary. Such transmission systems also typically provide for one or more planetary gearsets in order to provide various ratios of torque and to ensure that the available torque and the respective tractive power demand are matched to each other.
Transmissions are generally referred to as manually actuated or automatic transmission. Manual transmission generally include mechanical mechanisms for coupling rotating gears to produce different ratio outputs to the drive wheels.
Automatic transmissions are designed to take automatic control of the frictional units, gear ratio selection and gear shifting. A thorough description of general automatic transmission design principals may be found in "Fundamentals of Automatic Transmissions and Transaxles," Chrysler Corporation Training Manual No. TM-508A. Additional descriptions of automatic transmissions may be found in U.S. Pat. No. 3,631,744, entitled "Hydromatic Transmission," issued Jan. 4, 1972 to Blomquist, et al., and U.S. Pat. No. 4,289,048, entitled "Lock-up System for Torque Converter," issued on Sept. 15, 1981 to Mikel, et al. Each of these patents is hereby incorporated by reference.
In general, the major components featured in such an automatic transmission are: a torque converter as above-mentioned; fluid pressure-operated multi-plate drive or brake clutches and/or brake bands which are connected to the individual elements of the planetary gearsets in order to perform gear shifts without interrupting the tractive power; one-way clutches in conjunction with the frictional units for optimization of power shifts; and transmission controls such as valves for applying and releasing elements to shift the gears (instant of shifting), for enabling power shifting, and for choosing the proper gear (shift point control), dependent on shift-program selection by the driver (selector lever), accelerator position, the engine condition and vehicle speed.
The control system of the automatic transmission is typically hydraulically operated through the use of several valves to direct and regulate the supply of pressure. This hydraulic pressure control will cause either the actuation or deactuation of the respective frictional units for effecting gear changes in the transmission. The valves used in the hydraulic control circuit typically comprise spring-biased spool valves, spring-biased accumulators and ball check valves. Since many of these valves rely upon springs to provide a predetermined amount of force, it will be appreciated that each transmission design represents a finely tuned arrangement of interdependent valve components. While this type of transmission control system has worked well over the years, it does have its limitations. For example, such hydraulically controlled transmissions are generally limited to one or a very small number of engines and vehicle designs. Therefore, considerable cost is incurred by an automobile manufacturer to design, test, build, inventory and repair several different transmission units in order to provide an acceptable broad model line for consumers.
Additionally, it should be appreciated that such hydraulically controlled transmission systems cannot readily adjust themselves in the field to compensate for varying conditions such as normal wear on the components, temperature swings and changes in engine performance over time. While each transmission is designed to operate most efficiently within certain specific tolerances, typical hydraulic control systems are incapable of taking self-corrective action on their own to maintain operation of the transmission at peak efficiency.
However, in recent years, a more advanced form of transmission control system has been proposed, which would offer the possibility of enabling the transmission to adapt itself to changing conditions. In this regard, Leising, et al. U.S. Pat. No. 3,956,947, issued on May 18, 1976, which is hereby incorporated by reference, sets forth a fundamental development in this field. Specifically, this patent discloses an automatic transmission design which features an "adaptive" control system that includes electrically operated solenoid-actuated valves for controlling certain fluid pressures. In accordance with this electric/hydraulic control system, the automatic transmission would be "responsive" to an acceleration factor for controlling the output torque of the transmission during a shift from one ratio of rotation (between the input and output shafts of the transmission) to another. Specifically, the operation of the solenoid-actuated valves would cause a rotational speed versus time curve of a sensed rotational component of the transmission to substantially follow along a predetermined path during shifting.
3. Objects Of The Present Invention
It is one of the principal objects of the present invention to provide a significantly advanced electronically controlled transmission which is fully adaptive. By fully adaptive, it is meant that substantially all shifts are made using closed-loop control (i.e., control based on feedback). In particular, the control is closed loop on speed, speed ratio, or slip speed of either N.sub.t (turbine) of the torque converter and N.sub.e (engine) or a combination of N.sub.t and N.sub.o (output) which will provide the speed ratio or slip speed. This transmission control is also capable of "learning" from past experience and making appropriate adjustments on that basis.
Another object of the present invention is to provide an automatic transmission in which the shift quality is maintained approximately uniform regardless of the engine size, within engine performance variations or component conditions (i.e. the transmission control system will adapt to changes in engine performance or in the condition of the various frictional units of the transmission).
It is a more specific object of the present invention to provide a method of determining the acceleration of a turbine in a torque converter of an automatic transmission to control transmission operation during a shift or gear change.
This application is one of several applications filed on the same date, all commonly assigned and having similar Specification and Drawings, these applications being identified below.
SUMMARY OF THE INVENTION
To achieve foregoing objects, the present invention provides a comprehensive four-speed automatic transmission system. While this transmission system particularly features a fully adaptive electronic control system, numerous other important advances are incorporated into this unique transmission system, as will be described below in detail.
The transmission control system includes a microcomputer-based controller which receives input signals indicative of engine speed, turbine speed, output speed (vehicle speed), throttle angle position, brake applications, predetermined hydraulic pressure, the driver selected gear or operating condition (PRNODDL), engine coolant temperature, and/or ambient temperature. This controller generates command or control signals for causing the actuation of a plurality of solenoid-actuated valves which regulate the application and release of pressure to and from the frictional units of the transmission system. Accordingly, the controller will execute predetermined shift schedules stored in the memory of the controller through appropriate command signals to the solenoid-actuated valves and the feedback which is provided by various inputs signals.
Another primary feature of the present invention is to provide an adaptive system based on closed-loop control. In other words, the adaptive control system performs its functions based on real-time feedback sensor information, i.e., the system takes an action which affects the output, reads the effect, and adjusts the action continuously in real-time. This is particularly advantageous because the control actuations can be corrected as opposed to an open loop control in which signals to various elements are processed in accordance with a predetermined program.
In accordance with one aspect of the present invention, the controller is programmed to determine the acceleration of the turbine in the torque converter to control transmission operation during a shift or gear change by counting the number of teeth during a predetermined cycle and dividing that tooth count by the actual time elapsed between the first and last tooth.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiment, the appended claims and in the accompanying drawings in which:
FIG. 12 is a flow chart of the overall operational methodology of the transmission controller according to the present invention;
FIGS. 13A-13C are flow charts of the shift select methodology of FIG. 12 according to the present invention;
FIGS. 14A-D illustrate the shift schedule methodology according to the present invention; FIG. 14A is a flow chart of the shift schedule methodology of FIG. 12; and FIGS. 14B-14D are shift schedule graphs;
FIGS. 15A-B illustrate the PSLOPE methodology according to the present invention; FIG. 15A is a flow chart of the PSLOPE methodology of FIGS. 14; and FIG. 15B is a graph of the method used in FIG. 15A;
FIGS. 16A-D are flow charts of the shift methodology of FIG. 12 according to the present invention; FIG. 16A is a flow chart of the upshift methodology; FIGS. 16B and 16C are flow charts of the downshift methodology; and FIG. 16D is a flow chart of the garage shift methodology.
TRANSMISSION CONTROL METHOD
Referring to FIG. 12, the logic or methodology of the transmission controller 3010 is shown at 800. When the key of the vehicle is turned on, power-up of the transmission controller 3010 occurs in bubble 802. Next, the transmission controller 3010 performs or enters a seven millisecond (7 ms.) main program or control loop. At the beginning of the main control loop, the methodology advances to block 804 called shift select to "orchestrate" various methods used to determine the operating mode or gear, i.e. first gear, the transmission 100 is presently in and which gear the transmission 100 should be in next, and comparing the two to each other to determine if a shift is required. The methodology advances to bubble 806 to calculate the speed and acceleration of the turbine 128, output gear 534 and engine crankshaft 114. The transmission controller 3010 receives input data from the turbine speed sensor 320 (turbine speed N.sub.t), output speed sensor 546 (output speed N.sub.o) and engine speed sensor (not shown) (engine speed N.sub.e) in circle 808. In bubble 80 g, the engine speed N.sub.e, turbine speed N.sub.t and output speed N.sub.o are calculated from the input data. The methodology advances to bubble 810 called the shift schedule to be described under section heading "SHIFT SCHEDULE METHOD". The shift schedule bubble 810 reads or determined the shift lever position 606, PRNODDL, of the manual lever 578 by contact switch sensor (NS.sub.1, NS.sub.2) (See FIG. 4B) in circle 812. The shift schedule bubble 810 also determines the throttle angle THRT ANGLE of the engine, to be described under section heading " THROTTLE ANGLE COMPUTATION AND FAILURE DETECTION", by an input of a potentiometer (not shown) connected to the throttle (not shown) in circle 814. The shift schedule bubble 810 further determines the engine temperature, to be described under section heading "PRESSURE SWITCH TEST AND TRANSMISSION TEMPERATURE DETERMINATION METHOD" in circle 816. The shift schedule bubble 810 uses the data items such as output speed N.sub.o in circle 815 (generated by bubble 806), PRNODDL (generated by circle 812) and throttle angle (generated by circle 814) to determine the appropriate gear the transmission 100 should be placed.
The methodology advances to bubble 818 which outputs the appropriate command signals to the solenoid-actuated valves 630, 632, 634 and 636 and properly energizes or de-energizes them based on which gear the transmission 100 is in, as determined by circle 812. The methodology advances to bubble 820 to execute diagnostic or monitoring routines. In diagnostic bubble 820, the transmission controller 3010 determines if the proper pressure switches 646, 648 and 650, previously described, are pressurized by either looking for signals from a specific pressure switch combination for the present in-gear condition of the transmission 100 or from a specific pressure switch to a non-controlling clutch during a pressure switch test to be described. The transmission controller 3010 also determines if the wires in the control system are not shorted or open by looking for a flyback voltage or EMF spike during a solenoid continuity test to be described under section "SOLENOID CONTINUITY TEST METHOD". The methodology then advances to diamond 822 and determines whether a failure has occurred. If a failure has occurred, the methodology advances to block 824 in which the transmission controller 3010 de-energizes the solenoid-actuated valves 630, 632, 634 and 636 which assume their normal positions to allow the transmission 100 to operate in second gear in the drive mode, i.e. limp-home mode previously described. If a failure has not occurred, the methodology advances to the shift select block 804. Based on the calculated speeds and shift schedule output (SSOUTP), the methodology determines if a shift is required. This process is done every 7 ms.
Since the shift select block 804 compares the gear the transmission 100 is presently in, to the SSOUTP, the methodology advances to diamond 826 and determines if a shift or gear change is required. If a shift is required, the methodology advances to block 828 called the shift logic to be described herein. Otherwise, if a shift is not required, the methodology advances to diamond 830 and looks at the lock-up schedules, i.e. a plot of THRT ANGLE verses N.sub.t, etc., to determine if lock-up of the torque converter 110 is required. If lock-up is not required, the methodology returns to the beginning of the shift select block 804 again for another 7 ms. loop. Otherwise, if lock-up is required, the methodology advances to diamond 832 and determines if the torque converter 110 is presently locked-up by looking for a flag that has previously been set during full lock-up of the torque converter 110. If the torque converter 110 is presently locked-up, the methodology returns to the shift select block 804. Otherwise, the methodology advances to block 834 called partial lock-up logic or methodology, to described under section heading "TORQUE CONVERTER LOCK-UP METHOD", for the torque converter 110.
If a shift or gear change is needed or required, the shift logic block 828 uses one of twelve unique shift programs or routines. The shift routines are 1-2, 2-3, 2-4, 3-4 (upshifts); 4-3, 4-2, 3-2, 3-1, 2-1, (downshifts); and N-1, R-N, N-R (garage shifts) to be described herein. The shift logic block 828 has to identify the proper shift logic routine, and then execute it. The shift logic block 828 controls the solenoid-actuated valves 630, 632, 634 and 636 to shift the transmission 100 from its present gear to the next gear in a smooth manner.
After the shift logic block 828, the methodology advances to diamond 836 and determines if lock-up of the torque converter 110 is required as previously described. If lock-up is required, the methodology advances to diamond 838 and determines whether the torque converter 110 is already locked-up as previously described. If the torque converter is not already locked-up, the transmission controller 3010 executes the partial lock-up block 834, to be described herein.
The partial lock-up block 834 is used to reduce slip of the torque converter 110. Slip equals N.sub.e minus N.sub.t. The partial lock-up block 834 instructs or causes the transmission 100 to fully lock, partially lock or fully unlock the torque converter 110. If unlock is desired, the transmission controller 3010 will hold the solenoid-actuated valve 636 in the de-energized or normally vented mode to move the LU switch valve 614 and allow fluid pressure to disengage the lock-up clutch 186. If partial lock is desired, the transmission controller 3010 will reduce slip to a low or predetermined desired value, but not completely eliminate it. The transmission controller 3010 calculates the slip by N.sub.e minus N.sub.t based on the input from the sensors previously described. The transmission controller 3010 compares this to a predetermined desired value of slip, e.g. 60 r.p.m., and thus, determines if the torque converter 110 is slipping too much or too little. If too much slip occurs, the transmission controller 3010 will increase the duty cycle ("ON" time) of the low/reverse clutch solenoid-actuated valve 636 and the LU switch valve 614, which will increase the pressure differential across the lock-up clutch assembly 186 and thus, decrease the slip. This technique is called "pulse-width modulation".
If full lock-up is desired, the transmission controller 3010 will gradually increase the fluid pressure to the lock-up clutch 186, adding more "ON" cycle time to the solenoid-actuated valve 636 thereby increasing the "ON" cycle time at the LU switch valve 614 until maximum, resulting in zero slip.
Returning to diamond 836, if the transmission controller 3010 determines that lock-up of the torque converter 110 is not required, the methodology advances to bubble 840 to execute diagnostic or monitoring routines as previously described. Similarly, if the transmission controller 3010 determines that the torque converter 110 is already locked-up in diamond 838, the methodology advances to bubble 840 to execute diagnostic or monitoring routines as previously described. Further, once the partial lock-up block 834 is completed, the methodology advances to bubble 840 to execute diagnostic or monitoring routines as previously described.
From diagnostic bubble 840, the methodology advances to diamond 842 and determines whether a failure has occurred as previously described. If a failure has occurred, the methodology advances to block 844 and causes the transmission 100 to default to or operate in second gear. Otherwise, if no failure occurs in diamond 842, the methodology advances to diamond 846 and determines if the time period for the diagnostic loop has expired by any suitable method such as looking at a counter. If the time has not expired, the methodology advances to bubble 840 to execute the diagnostic routines again until the time period has expired. If the time period has expired, the methodology advances to bubble 848 to calculate speeds N.sub.e, N.sub.t and N.sub.o as previously described. The methodology then advances to bubble 850 to perform another shift schedule as previously described using PRNODDL circle 852, output speed N.sub.o circle 855, THRT ANGLE circle 854, and engine temperature circle 856.
To perform the shift in a smooth manner, the transmission controller 3010 slips the clutches of the multi-clutch assembly 300. The transmission controller 3010 has to control the pressure on applying clutches and releasing clutches in an orchestrated manner. To do this, the methodology advances from the shift schedule bubble 850 to bubble 858 and determines the appropriate rate of acceleration, called the "desired acceleration" (alpha.sub.desired or .alpha.*) to control the turbine 128. The desired acceleration may be predetermined by an equation, point/slope interpolation or any other suitable method. The methodology advances to bubble 860 and calculates the present acceleration (alpha.sub.t or .alpha..sub.t) of the turbine 128 based on turbine speed N.sub.t which tells the transmission controller 3010 how quickly the shift is happening. The transmission controller 3010 indirectly compares the value of desired acceleration with the calculated acceleration. This may be accomplished by placing the above values into an equation to decide the duty cycle for proportional control to be described. The methodology advances to bubble 862 to output the appropriate command signals to either actuate and/or deactuate (turn logically either "ON" or "OFF") the solenoid-actuated valves 630, 632, 634 and 636 for the engaging (apply) or disengaging (release) of the clutches.
For upshifts, if the turbine 128 is decelerating too fast, the transmission controller 3010 reduces the pressure on the applying clutch by either actuating and/or deactuating the solenoid-actuated valves 630, 632, 634 and 636 in bubble 862. For downshifts, if the turbine 128 is accelerating too rapidly, the transmission controller 3010 increases the pressure on the applying clutch by either actuating and/or deactuating the solenoid-actuated valves 630, 632, 634 and 636 in bubble 862. If the turbine assembly 128 is accelerating at the desired acceleration level, the solenoid-actuated valves 630, 632, 634 and 636 are either actuated and/or deactuated to obtain the shift or gear change. At the end of 7 ms. loop, the methodology advances to diamond 864. The transmission controller 3010 tallies the ratios of N.sub.t to N.sub.o again to determine if the shift or gear change is complete. If N.sub.o and N.sub.t are at proper values, i.e. ratio.times.N.sub.o =N.sub.t for a predetermined time period which is different for each shift, the transmission controller 3010 determines that the shift or gear change is complete. The methodology returns to the beginning of the control loop to the shift select block 804. If the shift or gear change is not complete, the methodology returns to the shift logic block 828 to repeat the method as previously described.
SHIFT SELECTION METHOD
The shift "select" routine or method in block 804 of FIG. 12 falls in the main loop immediately after system start-up in bubble 802 of FIG. 12. The shift schedule routine of bubble 810 is called before shift selection analysis is performed. All other key variables such as output speed N.sub.o, turbine speed N.sub.t, acceleration, etc. are also updated prior to shift selection analysis. The shift schedule routine of bubble 810 determines the appropriate gear the transmission 100 of the vehicle should be placed in (See FIG. 13B) as described subsequently herein. This information is conveyed by setting the bits of "shift schedule output" (SSOUTP). The shift selection block 804 compares the gear related bits of the in-gear code (IGCODE) as defined by circle 812 and SSOUTP. If they are equal, no shift is required. In this case, the methodology will decode what gear the transmission 100 is in and will revalidate the proper "clutch" and "solenoid" states (i.e. either logically "ON" or "OFF") of the valves 630, 632, 634 and 636 FIGS. 5A-L).
The shift selection method (FIG. 13B) has enormous complexity. In order to minimize the size of the method to a manageable level and to derive RAM and ROM efficacy, a technique using a shift "control table" is employed. Each row of the shift control table has four bytes. The shift control table format is defined as follows:
As illustrated in Figure 13A, the shift select block 804 is generally shown for a shift selection while the transmission 100 is operating "in gear", i.e. the transmission 100 is presently in first gear for example. After power-up in bubble 802 of FIG. 12, the methodology enters the shift select through bubble 866. The methodology advances to block 868 and points to the beginning or start of the shift control table (first row), previously described, which is stored in memory. The methodology advances to block 870 and prepares a "select mask" (M) from which the IGCCDE and SSOUTP are "logically ANL-ed". The methodology advances to block 872 and compares mask (M) with the first byte in the shift control table row. The methodology advances to diamond 874 and determines whether a matching row was found. If a matching row was found, the methodology advances to block 876 and points to the next row in the shift control table. The methodology then loops back to diamond 874 previously described.
If a matching row was found at diamond 874, the methodology advances to diamond 876 and determines whether the present IGCODE equals the second byte of the shift control table row. If the present IGCODE equals the second byte, the methodology advances to block 878 and picks the third byte containing the shift to be performed, i.e. first to second gear. If the present IGCODE does not equal the second byte, the methodology advances to block 880 and picks the fourth byte containing the shift to be performed. The methodology advances from blocks 878 and 880 to bubble 882. At bubble 882, the methodology returns or goes to top of shift in shift logic block 828 of FIG. 12 to perform the shift just selected. The shift select block 804 is shown schematically in FIG. 13B.
If the present shift is to be abandoned for a new shift, i.e. a shift selection while the transmission 100 is presently performing a shift, a selection process called "change-mind" analysis is used as illustrated in FIG. 13C. During the shift loop, the methodology enters the change-mind portion of the shift selection block 804 through bubble 884. The methodology then advances to diamond 886 and determines whether a new shift schedule is different from the present shift schedule by looking at the shift schedule output (SSOUIP) which may be a coded register. If not, the methodology advances to bubble 888 and determines that change-mind analysis is not allowed and continues the present shift. If the new shift schedule (SSCUTP) is different from the present shift schedule, the methodology advances to block 890 and vectors to the proper change-mind processing point based on a change mind table stored in memory which is similar to the shift control table. In other words, the methodology uses a vector table oriented method for analysis of each "present shift" and jumps to the proper process point. The methodology then advances to block 892 and performs checks using key variables (i.e. speeds, throttle angle, speed ratios, SSOUTP, IGCCDE, etc.) at its appropriate processing point. The methodology advances to diamond 894 and determines whether change-mind conditions are valid by the old SSOUTP not matching the new or recent SSOUTP. If the conditions are not valid, the methodology advances to bubble 888 previously described to continue the present shift. If the change-mind conditions are valid, the methodology advances to bubble 896 and aborts the present shift and selects the new shift from the processing point.
SHIFT SCHEDULE METHOD
The shift schedule method determines the appropriate gear in which the transmission 100 should be placed. The shift schedule method first determines the present gear of the transmission 100 by the shift lever position 606 of the manual lever 578 in circle 812 of FIG. 12. Based on the shift lever position 606, the shift schedule method determines the appropriate gear in which the transmission 100 should be placed.
Referring to FIG. 14A, the bubble 810 of FIG. 12 for the shift schedule method is shown. The methodology enters from the shift select block 804 through bubble 900 and advances to diamond 902. At diamond 902, the methodology determines whether the shift lever position (SLP) 606 of the manual lever 578 is park P or neutral N by reading a coded signal from the sensors NS.sub.1 and NS.sub.2 (FIG. 4B) to be described. If SLP 606 is park or neutral, the methodology advances to block 904 and sets the new output (SSOUTP) of the shift schedule (SS) to neutral. The methodology then returns or emits through bubble 906.
At diamond 902, if SLP 606 is not park or neutral, the methodology advances to diamond 908 and determines whether SLP 606 is reverse R by the signal from the sensors NS.sub.1 and NS.sub.2. If SLP 606 is reverse, the methodology then advances to block 910 and sets shift schedule to reverse. The methodology then returns or emits through bubble 906.
At diamond 908, if SLP 606 is not reverse, the methodology advances to block 912 concludes or determines that SLP 606 is equal to overdrive OD, drive D or low L. The methodology then advances to block 914 and selects two adjacent lines based on the present shift schedule and the shift schedule graphs shown in FIGS. 14B through 14D for a SLP 606 of overdrive OD, drive D or low L. The methodology advances to block 916 and scans these lines using a technique called "point slope" (PSLOPE), to be described under section heading "PSLOPE METHOD" (FIGS. 15A and 15B) which is a linear interpolation technique (N.sub.o on X-axis and throttle angle on Y-axis). The methodology advances to diamond 918 and determines whether there is a new shift schedule to a coastdown shift, i.e. second to first gear from the SSOUTP (for a downshift) and throttle angle (for coast versus kick). If there is a new shift schedule to a coastdown shift, the methodology advances to block 920 and checks the gear ratios of the gear assembly 500 by performing speed calculations to avoid a "shock" from a power-plant reversal situation. A power-plant reversal situation or condition exists when the wheels of the vehicle drive the engine through the transmission during deceleration rather than the engine driving the transmission, in turn, driving the wheels. The methodology advances to diamond 922 and determines whether a power-plant reversal situation or condition exists. If a power-plant reversal condition exists, the methodology advances to block 924 and does not change the shift schedule. The methodology returns or exits through bubble 926.
At diamond 918, if there is not a new shift schedule to a coastdown shift, the methodology advances to block 928. Also, if a power-plant reversal condition does not exist at diamond 922, the methodology advances to block 928. At block 928, the methodology allows for a new shift schedule. The methodology then advances to block 930 and checks for diagnostic situations or conditions as previously described in conjunction with FIG. 12. The methodology advances to diamond 932 and determines whether a diagnostic situation or condition exists. If a diagnostic condition does not exist, the methodology advances to block 934 and allows the shift schedule to proceed or be changed to the new shift schedule. If the diagnostic condition does exist, the methodology advances to block 936 and does not change the shift schedule. The methodology advances from blocks 934 and 936 to bubble 938 and exits or returns.
PSLOPE METHOD
Referring to FIGS. 15A and 15B, the "point slope" (PSLOPE) routine of block 916 of FIG. 14A is shown. The PSLOPE method determines the throttle angle given output speed N.sub.o by scanning the shift lines in FIGS. 14B through 14D stored as a table in the memory of the transmission controller 3010. At the start of the PSLOPE routine in bubble 1000 of FIG. 15A, the methodology advances to block 1002 and temporarily stores the value for X in the memory of the transmission controller 3010. The methodology then advances to diamond 1004 and determines whether X is less than or equal to X.sub.o (FIG. 15B) which is a point on the shift line. If X is less than or equal to X.sub.o, the methodology advances to block 1006 and gets or obtains the value for Y.sub.o and returns or emits through bubble 1008. If X is greater than X.sub.o, the methodology advances to diamond 1010 and determines whether X is less than X.sub.R. If X is less than X.sub.R, the methodology advances to block 1012 and computes the slope between the points X.sub.R and X.sub.R-1. The methodology then advances to block 1014 and computes Y based on Y.sub.R plus slope. The methodology then returns or emits through bubble 1016.
At diamond 1010, if X is not less than X.sub.R, the methodology advances to diamond 1018 and determines whether the method is at the end of a table of values for the shift schedule graphs (FIGS. 14B-D), i.e. Y.sub.o ; Y.sub.o ; X.sub.R ; Y.sub.R ; X.sub.n ; Y.sub.n. If the method is not at the end of the table, the methodology advances to block 1020 and goes to the next row of the table. The methodology then loops back to diamond 1010.
If the methodology is at the end of the table at diamond 1018, the methodology advances to block 1022 and concludes or determines that the value for X is not in the table but greater than X.sub.n (FIG. 15B), and gets the Y.sub.n value, i.e. the last value Y.sub.n from the data table based on the value for X.sub.n. The methodology then returns or emits through bubble 1016.
SHIFT LOGIC METHOD
The shift logic block 828 contains twelve unique shift programs. The shift logic block 828 identifies the shift logic or routine to be executed. For example, if the transmission 100 is in first gear and the shift schedule output (SSOUTP) changes to call for second gear, the shift selection block 804 picks a SHCODE and shift logic block 828 identifies and executes the SHCODE for first to second (1-2) logic.
Each of the twelve different shifts involves extensive calculations and logical manipulations to determine the "ON" Or "OFF" states of the solenoids of the solenoid-actuated valves 630, 632, 634 and 636 (FIGS. 5A-L) for engaging (applying) or disengaging (releasing) of the clutches for the shifts. These shifts are organized into three sets of shifts as follows: upshifts 1-2, 2-3, 3-4 and 2-4; downshifts 2-1, 3-1, 4-3, 4-2 and 3-2; and garage shifts N-1, N-R and R-N.
The methodology consists of three major routines, one for each of the above sets of shifts. To make this possible, a "Control Table" method is used. The key parametric entities are imbedded in a shift control table as follows:
All calibration variables are segregated into a separate table called a "Volume Table" for example, as follows:
Thus, during product development, the key flow-rate and volumetric parameters can be efficiently and manageably altered. As a result, each major shift routine (upshift, downshift or garage shift) can do one of its many shifts just by getting the necessary fixed parameters from the shift control table and the calibration (volumetric, flow rates, etc.) data from the volume tables.
Accordingly, this shift logic method provides the following advantages: efficient management of ROM and RAM resources of the transmission controller 3010; efficiency during product calibration cycle; and defect preventiveness during development due to the segregation by upshifts, downshifts and garage shifts and by fixed versus calibration parameters.
Referring to FIG. 16A, for upshifts of the shift logic block 828 of FIG. 12, the methodology enters the start or top of shift in the shift logic block 828 through bubble 1100. The methodology advances to diamond 1102 and determines whether the torque converter 110 is presently in the lock-up mode as previously described. If the torque converter 110 is presently locked, the methodology advances to block 1104 and instructs the transmission controller 3010 to unlock the torque converter 110 when slip from the present gear toward the target gear begins, i.e. from first to second gear. The methodology then advances to block 1106.
At diamond 1102, if the torque converter 110 is not in the lock-up mode, the methodology advances to block 1106. At block 1106, the transmission controller 3010 computes variables, such as t.sub.f (time remaining to nearly fill the apply clutch, t.sub.r (time to nearly release), DC.sub.t (torque phase duty cycle) etc., states/flags to be used in shift logic equations and intercepts/calculates variables used for "learning", to be described under section heading "LEARN METHODOLOGY" at the end of the shift. The methodology advances to block 1108 and solves a predetermined logic equation for the apply element such as a clutch. The methodology then advances to diamond 1110 and determines whether the solenoid for the apply element or oncoming clutch should be logically "ON" based on calculated speeds, throttle angle and SSOUTP.
It should be appreciated that the friction element (apply or release) such as a clutch is turned logically "ON or OFF" by either the energization or de-energization of the solenoid-actuated valve. It should also be appreciated that "ON" or "OFF" can be either "applying or venting" of the function element.
If the apply clutch should be ON, the methodology advances to diamond 1112 and determines whether the apply clutch is under duty cycle control, i.e. solenoid-actuated valve to the clutch is cycled "ON" and "OFF", by looking for a flag previously set. If the apply clutch is not under duty cycle control, the methodology advances to block 1114 and turns ON or applies the apply clutch by energizing or de-energizing the solenoid of the respective solenoid-actuated valve. If the apply clutch is under duty cycle control, the methodology advances to block 1116 and starts or continues the duty cycle.
At diamond 1110, if the apply clutch should not be ON, or applied the methodology advances to block 1118 and turns OFF or disengages the apply clutch. The methodology advances from blocks 1114, 1116 or 1118 to block 1120 and solves a predetermined the release clutch or off-going clutch logic equation. The methodology advances to diamond 1122 and determines whether the release clutch or off-going clutch should be ON based on calculated speeds, throttle angle and SSOUTP. If the release clutch should not be ON, the methodology advances to block 1124 and turns OFF or disengages the release clutch. The methodology then returns or emits through bubble 1126.
At diamond 1122, if the release clutch should be ON or applied, the methodology advances to diamond 1128 and determines whether the release clutch is under duty cycle control by looking for a flag as previously described. If the release clutch is not under duty cycle control, the methodology advances to block 1130 and turns ON or applies the release clutch. The methodology returns or emits through bubble 1126.
At diamond 1128, if the release clutch is under duty cycle control, the methodology advances to block 1132 and starts or continues the duty cycle. The methodology emits through bubble 1126.
Referring to FIGS. 16B and 16C, the downshift logic for the shift logic block 828 of FIG. 12 is shown. The methodology enters through bubble 1200. The methodology advances to diamond 1204 and determines whether the torque converter 110 is unlocked as previously described. If the torque converter 110 is not unlocked, the methodology advances to block 1206 and aborts partial or full lock-up operation. The methodology advances to block 1208.
At diamond 1204, if the torque converter 110 is unlocked, the methodology advances to block 1208. At block 1208, the transmission controller 3010 computes variables and states of flags to be used in similar shift logic equations of the upshift logic. The methodology advances to diamond 1210 and determines whether the present shift is a downshift to first gear by the SSOUTP. If the present shift is a downshift to first gear, the methodology advances to diamond 1212 and determines whether the solenoid switch valve 610 has moved to the low gear position (See FIG. 5E). The position of the solenoid switch valve 610 is determined by checking pressure switch data from the pressure switches 646, 648 and 650 within a predetermined time period. If the solenoid switch valve 610 has moved to the low gear position, the methodology advances to diamond 1214 and determines whether the solenoid switch valve 610 has moved back to the high gear or lock-up position (See FIG. 5F). If the solenoid switch valve 610 has moved back to the high gear position, the methodology returns or emits through bubble 1216.
At diamond 1212, if the solenoid switch valve 610 has not moved to the low gear position, the methodology advances to block 1218 and executes solenoid switch valve control logic (energizing and de-energizing the solenoid-actuated valves 634 and 636), previously described, to move the solenoid switch valve 610 to the low gear position. The methodology then advances to block 1220.
At diamond 1214, if the solenoid switch valve 610 has not moved back to the high gear position, the methodology advances to block 1220. At diamond 1210, if the present shift is not a downshift to first gear, the methodology advances to block 1220. At block 1220, the transmission controller 3010 solves the release clutch shift logic equation. The methodology advances to diamond 1222 and determines whether the release clutch should be turned ON or applied as previously described. If the release clutch should not be turned ON, the methodology advances to block 1224 and turns OFF or disengages the release clutch.
At diamond 1222, if the release clutch should be turned ON, the methodology advances to diamond 1226 and determines whether the release clutch is in the duty cycle made as previously described. If the release clutch is not in the duty cycle mode, the methodology advances to block 1228 and turns ON or applies the release clutch. If the release clutch is in the duty cycle mode, the methodology advances to block 1230 and starts or continues the release clutch duty cycle. The methodology advances from blocks 1224, 1228 and 1230 to diamond 1232.
At diamond 1232, the transmission controller 3010 determines whether the present shift is a downshift to first gear as previously described. If the present shift is a downshift to first gear, the methodology advances to diamond 1234 and determines whether the solenoid switch valve 610 has roved to the low gear position as previously described. If the solenoid switch valve 610 has not moved to the low gear position, the methodology emits or returns through bubble 1236. If the solenoid switch valve 610 has moved to the low gear position, the methodology advances to block 1238. If the present shift is not a downshift to first gear at block 1232, the methodology advances to block 1238.
At block 1238, the transmission controller 3010 solves the shift logic equation for the apply clutch and intercepts/calculates the necessary data for "learning" at the end of the shift to be described subsequently. The methodology advances to diamond 1240 and determines whether to turn ON the apply clutch.
If the transmission controller 3010 determines not to turn ON the apply clutch, the methodology advances to block 1242 and turns OFF or disengages the apply clutch. If the transmission controller 3010 determines to turn ON the apply clutch, the methodology advances to diamond 1244 and determines whether the apply clutch is in the duty cycle mode as previously described. If the apply clutch is not in the duty cycle mode, the methodology advances to block 1246 and turns ON the apply clutch. If the apply clutch is in the duty cycle mode, the methodology advances to block 1248 and starts or continues the apply clutch duty cycle. The methodology advances from blocks 1242, 1246 and 248 to block 1250.
At block 1250, the transmission controller 3010 solves a non-controlling clutch shift logic equation similar to the controlling shift logic equations needed for the shift to occur as previously described. A clutch other than one needed to make the shift or gear change is called the non-controlling clutch. This clutch is cycled ON and OFF by the appropriate solenoid-actuated valve to improve shift quality. The methodology advances from block 1250 to diamond 1252 and determines whether to turn ON or apply the non-controlling clutch based on calculated speeds, throttle angle and SSOUTP. If the transmission controller 3010 determines not to turn ON the non-controlling clutch, the methodology advances to block 1254 and turns OFF or disengages the non-controlling clutch. If the transmission controller 3010 determines to turn ON the non-controlling clutch, the methodology advances to block 256 and turns ON the non-controlling clutch. The methodology returns or emits from blocks 1256 and 1256 through bubble 1258.
Referring to FIG. 16C, the garage shift methodology for the shift logic block 828 of FIG. 12 is shown. The methodology enters the shift logic block 828 through bubble 1300. The methodology advances to block 1302 and turns the non-controlling clutches either ON or OFF, i.e. engages disengages the clutches not needed to perform the garage shifts. The methodology advances to diamond 1304 and determines whether the present shift is a garage shift to first gear by looking at SHCODE. If the present shift is a garage shift to first gear, the methodology advances to diamond 1306 and determines whether the solenoid switch valve 610 has moved to the first gear position (FIG. 5E) as previously described. If the solenoid switch valve 610 has not moved to the first gear position, the methodology advances to block 1308 and performs solenoid switch valve control logic as previously described. The methodology then emits or returns through bubble 1310.
At diamond 1304, if the shift is not a garage shift to first gear, the methodology advances to block 1312. At diamond 1306, if the solenoid switch valve 610 has moved to the first gear position, the methodology advances to block 1312. At block 1312, the transmission controller 3010 computes variables and states of flags to be used in a controlling shift logic equation similar to those in the upshift logic. The methodology advances to block 1314 and solves the controlling clutch shift logic equation. The methodology advances to diamond 1316 and determines whether to turn ON the controlling clutch as previously described. If the controlling clutch is not to be turned ON, the methodology advances to block 1318 and turns OFF the controlling clutch. If the controlling clutch is to be turned ON, the methodology advances to diamond 1320 and determines whether the controlling clutch is under duty cycle control as previously described. If the controlling clutch is not under duty cycle control, the methodology advances to block 1322 and turns ON the controlling clutch. If the controlling clutch is under duty cycle control, the methodology advances to block 1324 and starts or continues the apply clutch duty cycle. The methodology returns or emits from blocks 1318, 1322 and 1324 through bubble 1326.
ACCELERATION CALCULATION
The purpose of the acceleration calculation is to control transmission operation during a shift or gear change. The acceleration calculation determines the actual acceleration of the turbine 128. This is a major factor in determining overall response of the control system.
Referring to FIG. 12, the calculated speed bubble 806 is illustrated. At most speeds, the speed calculation is made by counting the number of teeth 319, 544 during a predetermined cycle and dividing that tooth count by the actual time elapsed between the first and last tooth. Time is measured by counting clock cycles in the transmission controller 3010. The tooth center lines are determined by reading a magnetic sensor 320, 546 for the sixty-tooth input clutch retainer hub 312 for turbine speed N.sub.t, and for the twenty-four-tooth second planet carrier 524 for output speed N.sub.o, respectively. At lower speeds, when no tooth passes during the 7 millisecond (ms.) cycle, the update rate must be extended to more than one predetermined cycle, i.e. 14 ms., 21 ms., etc., to provide data down to the minimum speed needed.
Referring to FIG. 12, the calculated acceleration bubble 860 is illustrated. Acceleration is calculated by dividing the speed change between the last two measurements by the average of the two elapsed times.
N.sub.t =calculated turbine r.p.m.
N.sub.o =calculated output r.p.m.
alpha.sub.t .alpha..sub.t =calculated turbine acceleration, r.p.m./sec.
n(i)=no. of teeth in latest count
n(i-1)=no. of teeth in previous count
T(i)=time required for n(i) teeth, seconds
T(i-1)=time required for n(i-1) teeth, etc.
For turbine speed N.sub.t and acceleration alpha.sub.t, the calculation range is from 40 to 6500 r.p.m. Acceleration must be calculated as soon as practical after reading turbine speed data because any time use slows the overall system response. For output speed N.sub.o, the calculation range is from 40 to 6000 r.p.m. Due to problems with low speed data integrity, the maximum change for any update must be limited to plus/minus 30 r.p.m. when the previous output speed is less than 300 r.p.m.
At low speeds (below about 1500 r.p.m.), an alternate method of calculating turbine acceleration is used. At higher speeds, however, the run-out inherent in the turbine speed wheel would generate a large first-order alternating acceleration term if this approach were used, thus interfering with good control.
To overcome this, a first-order filter is employed, which calculates acceleration over an entire revolution. Speed is calculated based on each quarter-revolution, the fourth previous speed (one revolution before) is subtracted, and the difference is divided by the time for the one revolution. Because this acceleration calculation is more delayed, particularly at low speed, anticipation is necessary in order to achieve acceptable frequency response.
The following table defines the speed and acceleration calculations as functions of .OMEGA., the number of quarter revolutions times. .OMEGA.=0 represents low speed operation. As the turbine accelerates, when 11 or more teeth (out of 60) pass in 7 ms., the switch to quarter revolution is initiated and .OMEGA. begins to increment. After the fifth quarter revolution, one revolution acceleration can be calculated; and after two more quarter revolutions anticipation is effected. Low speed operation is resumed when more than 11.3 ms. is required for a quarter revolution.
where:
n(i)=no. of teeth in latest count (assuming 60-tooth wheel)
n(i-1)=no. of teeth in previous count
T(i)=time required for n(i) teeth, seconds
T(i-1)=time required for n(i-1) teeth, etc.
N.sub.t =calculated turbine r.p.m.
.sub..alpha. (i)=calculated turbine acceleration, r.p.m./sec.
.sub..alpha.t =turbine acceleration term for use in shift logic
.sub..alpha.a =anticipated turbine acceleration, where
.sub..alpha.a =(1/4)*[(36-3B)*.sub..alpha. (i)-(52-5B)*.sub..alpha. (i-1)+(20-2B)*.sub.60 (i-2)]
.sub..alpha. (i-1)=calculated accel. for previous quarter revolution, etc.
B=INT [N.sub.t /512]; limit B.ltoreq. 9
The present invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.
Obviously, many modifications and variations are possible in light of the above teachings. Therefore, the subject invention may be practiced otherwise than as specifically described.
Claims
What is claimed is:
1. In a vehicle having an engine and a transmission including an input member, a torque converter for transmitting torque between a crankshaft of the engine and the input member of the transmission, the torque converter having a turbine connected to the input member, an output member, a gear assembly for changing the ratio of torque between the input member and the output member, a plurality of friction elements for shifting the gear assembly, a plurality of sensors for providing signals indicative of measurement data for predetermined conditions, a controller having memory for processing and storing the signals and predetermined values and for providing output signals, a method of determining the acceleration of a turbine in a vehicle transmission to control the operation of the transmission, said method comprising the steps of: during each predetermined time period, sensing the number of tooth centerlines which pass the speed sensor; sensing a time period between the passing of the last tooth and the end of the predetermined time period; taking the predetermined period time, subtracting the sensed time period and adding the sensed time period from the previous period to obtain the exact time sensed for the full passage of the teeth whose centerlines were sensed during the predetermined time period; calculating speed by dividing the sensed number of teeth by the exact time of passage of the same teeth; if no tooth centerline should pass in the predetermined time period, continue to sense for tooth centerlines and increase the time used in the speed calculation by the predetermined period time; repeat this as required to calculate speeds down to the desired level each time subtracting the sensed time period for the latest passing centerline from the accumulated period times and adding the sensed time period from the last previous period which observed a passing centerline to obtain the exact time of passage of all of the counted tooth centerlines; calculating the acceleration of the turbine by the difference between the calculated input speed and the previous input speed and dividing one-half of the sum of the exact time of passage used in the latest speed calculation and the previous calculation; and controlling the application of the friction elements in the transmission using the calculated acceleration.
2. In a vehicle having an engine and a transmission including an input member, a torque converter for transmitting torque between a crankshaft of the engine and the input member of the transmission, the torque converter having a turbine connected to the input member, an output member, a gear assembly for changing the ratio of torque between the input member and the output member, a plurality of friction elements for shifting the gear assembly, a plurality of sensors for providing signals indicative of measurement data for predetermined conditions, a controller having memory for processing and storing the signals and predetermined values and for providing output signals, a method of determining the acceleration of a turbine in a vehicle transmission to control the operation of the transmission, said method comprising the steps of: calculating the speed of the turbine by sensing the number of teeth of the turbine passing a sensor during a predetermined time period and dividing the sensed number of teeth by the predetermined time period; calculating the output speed of the transmission by sensing the number of teeth on an output member of the transmission passing a sensor during a predetermined time period and dividing the sensed number of teeth by the predetermined time period; calculating the acceleration of the turbine by the difference between the present calculated turbine speed and a previous calculated turbine speed and dividing by a predetermined constant multiplying the difference between the time required for a predetermined number of teeth and predetermined number of teeth minus one; and controlling the application of the friction elements in the transmission using the calculated acceleration.
3. In a vehicle having an engine and a transmission including an input member, a torque converter for transmitting torque between a crankshaft of the engine and the input member of the transmission, the torque converter having a turbine connected to the input member, an output member, a gear assembly for changing the ratio of torque between the input member and the output member, a plurality of friction elements for shifting the gear assembly, a plurality of sensors for providing signals indicative of measurement data for predetermined conditions, a controller having member for processing and storing the signals and predetermined values and for providing output signals, a method of determining the acceleration of a turbine in a vehicle transmission to control the operation of the transmission, said method comprising the steps of: sensing the number of teeth of the turbine passing a sensor during a quarter-revolution of the turbine; calculating the speed of the turbine based on the sensed number of teeth during a quarter-revolution o the turbine; subtracting the fourth-previous calculated speed of the turbine from the calculated speed of the turbine; calculating the acceleration of the turbine by dividing the difference between the present calculated speed and the fourth-previous calculated speed by a predetermined time period for one revolution of the turbine; and controlling the application of the friction elements in the transmission using the calculated acceleration.
Patent Citations (35)
| Patent | Date | Inventor | Cited By |
|---|---|---|---|
| US3876028 | 1975-04-01 | Asano et al. | |
| US3881368 | 1975-05-01 | Furuhashi et al. | |
| US3943345 | 1976-03-01 | Ando et al. | |
| US3956947 | 1976-05-01 | Leising et al. | |
| US4044634 | 1977-08-01 | Florus et al. | |
| US4073204 | 1978-02-01 | Dick | |
| US4082130 | 1978-04-01 | Dornfeld et al. | |
| US4131036 | 1978-12-01 | Ivey et al. | |
| US4174645 | 1979-11-01 | Ohmae et al. | |
| US4208925 | 1980-06-01 | Miller et al. | |
| US4220058 | 1980-09-01 | Petzold | |
| US4224842 | 1980-09-01 | Rabus et al. | |
| US4244244 | 1981-01-01 | Rembold et al. | |
| US4258591 | 1981-03-01 | Eckert et al. | |
| US4259882 | 1981-04-01 | Miller | |
| US4274142 | 1981-06-01 | Furuhashi et al. | |
| US4283970 | 1981-08-01 | Vukovich | |
| US4380048 | 1983-04-01 | Kishi et al. | |
| US4468988 | 1984-09-01 | Hiramatsu | |
| US4468989 | 1984-09-01 | Rosen | |
| US4485443 | 1984-11-01 | Knodler et al. | |
| US4527248 | 1985-07-01 | Takase et al. | |
| US4527678 | 1985-07-01 | Pierce et al. | |
| US4535412 | 1985-08-01 | Cederquist | |
| US4584906 | 1986-04-01 | Nagaoka et al. | |
| US4631628 | 1986-12-01 | Kissel | |
| US4667540 | 1987-05-01 | Yagi | |
| US4670852 | 1987-06-01 | Masaki et al. | |
| US4680988 | 1987-07-01 | Mori | |
| US4693142 | 1987-09-01 | Kurihara et al. | |
| US4707789 | 1987-11-01 | Downs et al. | |
| US4775938 | 1988-10-01 | Hiramatsu | |
| US4779490 | 1988-10-01 | Milunas et al. | |
| US4785689 | 1988-11-01 | Iwatsuki et al. | |
| US4803901 | 1989-02-01 | Hamano et al. |
Non-Patent Literature (2)
- Takeo Hiramatsu, et al., "Control Technology of Minimal Slip-Type Torque Converter Clutch", SAE Technical Paper 850460, (1985).
- M. Suga, et al., "The Control of the Lockup Clutch Used in the Microprocessor Controlled Automatic Transmission," 1 Mech. E., (1985).