METHOD FOR MONITORING A FIXED GEAR TRANSMISSION

Abstract

Method (200) for monitoring a fixed-gear transmission (10) comprising a plurality of interconnected planetary gear sets (20, 30, 40, 50) and a plurality of selectively activatable clutches (CB1R 61, CB38 62, C57R 63, C6789 64, CB123456 65, C4 66, CB29 67) during operation, wherein the method (200) comprises: Deriving a node speed relationship (equations 1, 2, 3, 4) for each of the planetary gear sets (20, 30, 40, 50) on the basis of the transmission ratios of the corresponding planetary gear set (20, 30, 40, 50) (202); Determine equivalent speed parameters for nodes of the planetary gear sets (20, 30, 40, 50) based on a gearbox input speed, an intermediate node speed and a gearbox output speed (204); Determining a clutch slip speed relationship (Equation 8) for each of the clutches (CB1R 61, CB38 62, C57R 63, C6789 64, CB123456 65, C4 66, CB29 67) based on the node speed relationships for the planetary gear sets (20, 30, 40, 50) and the equivalent speed parameters for the nodes of the planetary gear sets (20, 30, 40, 50) (206); dynamic monitoring, via speed sensors (72, 74, 76), of the transmission input speed (N I ), the inter-node rotational speed (N IS ) and the transmission output speed (N O )(210); and Calculate (Equation 14) a clutch slip speed (Nslip(C4)) for each of the clutches (20, 30, 40, 50) based on the respective clutch slip speed relationship (Equation 8) and the dynamically monitored transmission input speed (N I ), Inter-node rotational speed (N IS ) and gearbox output speed (N O )(212).

Description

[0001] The disclosure relates to a method for monitoring a fixed gear transmission.

[0002] Transmissions are applied to motor vehicles to transfer torque from a torque-generating device, such as an internal combustion engine, to a vehicle driveline for traction effort in response to operator demand. Transmissions include gearsets and clutches to transmit torque in one of a plurality of fixed gear ratios. Monitoring the operation of a transmission to detect clutch lockups, clutch neutral conditions, and other faults associated with clutch activation and deactivation can be challenging in a transmission configured with a significant number of fixed gear ratios, e.g., more than five, due to the relatively large amount of incremental speed change between adjacent fixed gear ratios.

[0003] DE 10 2007 053 784 A1 discloses a method for monitoring a hybrid transmission having fixed-gear operating modes and comprising a plurality of interconnected planetary gear sets and a plurality of selectively activatable clutches during operation. The method includes calculating a clutch slip speed by comparing, in the transmission, the monitored input speed with the monitored output speed multiplied by the gear ratio of the outgoing gear.

[0004] DE 10 2008 048 531 A1 discloses a method for monitoring a hybrid transmission during operation, which has fixed-gear operating modes and includes a plurality of interconnected planetary gear sets and a plurality of selectively activatable clutches. The method includes calculating a clutch slip speed based on the monitored speeds of a first and a second electric motor, the transmission output speed based on the gear ratios, and the relative speeds of the clutches and electric motors.

[0005] DE 10 2005 022 304 A1 teaches a method for monitoring a hybrid transmission during operation, which has fixed-gear operating modes and includes a plurality of interconnected planetary gear sets and a plurality of selectively activatable clutches. The method includes calculating a clutch slip speed of a first clutch based on monitored speeds of a first and a second electric motor, and a second clutch based on monitored speeds of the first and second electric motors and the output speed of the transmission.

[0006] It is the object of the invention to provide a method for monitoring a fixed gear transmission, in particular the clutch slip in such a transmission.

[0007] This object is achieved by a method having the features of claim 1 and a method having the features of claim 10.

[0008] Advantageous embodiments are specified in the dependent claims.

[0009] A fixed-gear transmission is described that includes a plurality of planetary gear sets and a plurality of clutches. A method for monitoring the fixed-gear transmission includes deriving a nodal speed relationship for each of the planetary gear sets based on a centerline distance and a gear ratio, and determining equivalent speed parameters for nodes of the planetary gear sets based on a transmission input speed condition, an intermediate node speed condition, and a transmission output speed condition. A clutch slip speed relationship is determined for each of the clutches based on the nodal speed relationships for the planetary gear sets and the equivalent speed parameters for nodes of the planetary gear sets. Speed ​​sensors monitor the input transmission speed, the intermediate node speed, and the transmission output speed.A clutch slip speed for each of the clutches is determined based on the respective clutch slip speed relationship and the monitored input transmission speed, the monitored intermediate node speed, and the monitored transmission output speed.

[0010] One or more embodiments will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 schematically illustrates a lever diagram of a fixed gear transmission and an accompanying transmission controller according to the disclosure; Fig. 2 schematically illustrates a clutch speed calculation routine including determining a clutch slip speed for one of the clutches based on a respective clutch slip speed relationship and dynamically monitored transmission speeds including transmission input speed, intermediate node speed, and transmission output speed, in accordance with the disclosure; Fig. 3 schematically shows a transmission clutch slip speed monitoring routine illustrating a process for detecting an occurrence of a clutch fault for the clutches of the transmission based on the clutch slip speed according to the disclosure; and Fig. 4 schematically illustrates one embodiment of a transmission node overspeed monitoring routine illustrating a process for detecting an occurrence of a node overspeed condition and remediation in response thereto in accordance with the disclosure.

[0011] Referring now to the drawings, in which the representations are for the sole purpose of illustrating certain exemplary embodiments and not for the purpose of limiting the same, Fig.1 schematically illustrates a lever diagram of a fixed-gear transmission 10 and accompanying transmission controller 15 configured to operate in one of a plurality of fixed-gear states. The transmission 10 is illustrative of one embodiment and provides the context for the Fig. 2, Fig. 3 and Fig. 4 described monitoring routines.

[0012] The transmission 10 is used, in one embodiment, to transfer torque between an input member 12 and an output member 14 of a vehicle, wherein the input member 12 is rotatably coupled to a torque generator, e.g., an internal combustion engine, and the output member 14 is rotatably coupled to a driveline to deliver tractive torque to vehicle wheels for propulsion. The transmission 10 includes a plurality of interacting planetary gears including a first planetary gear set 20, a second planetary gear set 30, a third planetary gear set 40, and a fourth planetary gear set 50. As shown, each of the planetary gear sets is a simple planetary gear set including a sun gear member, a plurality of planetary gears coupled via a common carrier member, and a ring gear member.Therefore, the first planetary gear set 20 includes a first sun gear 22, first planet gears 24, and a first ring gear 26; the second planetary gear set 30 includes a second sun gear 32, second planet gears 34, and a second ring gear 36; the third planetary gear set 40 includes a third sun gear 42, third planet gears 44, and a third ring gear 46; and the fourth planetary gear set 50 includes a fourth sun gear 52, fourth planet gears 54, and a fourth ring gear 56. Each of the aforementioned sun gears, planet gears, and ring gears corresponds to transmission speed nodes. Other transmission configurations and planetary gear sets including compound planet gears may be employed.

[0013] In one embodiment of the transmission 10, the transmission gearing arrangement is configured as follows. The specific values ​​are provided for illustrative purposes and are not intended to limit the concepts described herein. The first planetary gear set 20 is an output gear set having a tooth ratio of 83 / 37, a nominal ring gear / carrier gear ratio of 1.0, and a sun gear / carrier gear ratio of 2.24. The second planetary gear set 30 is an input gear set having a tooth ratio of 83 / 37, a nominal ring gear / carrier gear ratio of 1.0, and a sun gear / carrier gear ratio of 2.24. The third planetary gear set 40 is a reaction gear set having a tooth ratio of 74 / 25, a nominal ring gear / carrier gear ratio of 1.0, and a sun gear / carrier gear ratio of 2.96.The fourth planetary gear set 50 is an overdrive gear set having a gear ratio of 74 / 46, a nominal ring gear / carrier gear ratio of 1.0, and a sun gear / carrier gear ratio of 1.607. The transmission 10 includes a plurality of controllable clutch and brake components, including a controllable, selectable one-way clutch (CB1R) 61, a first brake (CB38) 62, a first clutch (C57R) 63, a second clutch (C6789) 64, a second brake (CB123456) 65, a third clutch (C4) 66, and a third brake (CB29) 67. As used herein, the terms “clutch” and “brake” refer to any type of selectively engageable torque-transmitting device, including, for example, single or compound friction plate clutches or packs, band clutches and brakes, and mechanical one-way clutches.A "clutch" rotatably couples rotation of two rotating components, and a "brake" fixes rotation of a rotating component to a transmission case 16. A hydraulic control circuit, preferably controlled by the transmission controller 15, controls the activation and deactivation of the aforementioned clutches and brakes to control power flow through the transmission 10. The aforementioned clutches and brakes may also be collectively referred to as "clutches."

[0014] The transmission 10 includes a plurality of speed sensors, including an input speed sensor 72 that monitors a rotational position and speed of the input member 12, an output speed sensor 74 that monitors a rotational position and speed of the output member 14, and one or more intermediate node speed sensors 76. As shown, there is a single intermediate node speed sensor 76 that monitors the speed of one of the intermediate nodes of the transmission 10. More specifically, in this embodiment, the intermediate node speed sensor 76 monitors the speed of the third sun gear 42. As discussed with reference to the clutch speed calculation routine 200 shown in Fig.2, monitored speeds from the input speed sensor 72, the output speed sensor 74, and the single intermediate node speed sensor 76 may be applied to directly and dynamically calculate a speed at each of the nodes in the illustrated nine-speed transmission 10 using information related to mechanical connection points of the transmission 10, as expressed in lever diagrams and related analytical tools. In an alternative embodiment including a ten-speed transmission, two intermediate node speed sensors are applied to directly calculate a speed at each of the nodes of the transmission. As shown, the single intermediate node speed sensor 76 monitors the speed of the third sun gear member 42 of the third planetary gear set 40.

[0015] The transmission controller 15 dynamically monitors inputs from each of the input speed sensor 72, the output speed sensor 74, and the intermediate node speed sensor 76 during operation. Each of the sensors 72, 74, 76 may be any speed sensing device capable of generating an electrically readable signal in response to the passage of a target component past the rotating element of interest, including, for example, a Hall effect sensor, a magnetostrictive sensor, a variable reluctance sensor, or other suitable edge sensing device. The target component preferably has a plurality of equally spaced detection edges, e.g., falling edges, indexed with equivalent amounts of rotation. In one embodiment, the target component has sixty (60) equally spaced falling edges indexed with 6° of rotation.The target component may employ different detection edge sizes. The signal output from each of the sensors 72, 74, and 76 may indicate the direction of rotation, i.e., a forward or reverse direction of rotation. The application and use of rotation-sensing devices is known to those skilled in the art.

[0016] Table 1 shows clutch and brake activation and power flow through the transmission 10 for the various gears, where the "X" indicates activation of the respective clutch to effect operation in the specified gear. Table corridor Translation ratio Ratio level CB1R CB38 C57R C6789 CB123456 C4 CB29 R -2,960 X X N - -0,63 1 4,689 X X 2 3,306 1,42 X X 3 3,012 1,10 X X 4 2,446 1,23 X X 5 1,923 1,27 X X 6 1,446 1,33 X X 7 1,000 1,45 X X 8 0,747 1,34 X X 9 0,617 1,21 X X

[0017] The terms controller, control module, module, control device, control unit, processor and similar terms refer to any one or various combinations of an application-specific integrated circuit / application-specific integrated circuits (ASIC), an electronic circuit / electronic circuits, a central processing unit / central processing units, e.g. a microprocessor / microprocessors and associated memory and storage devices (read-only, programmable, read-only, random access, hard disk, etc.) that execute one or more software or firmware programs or routines, a combinational logic circuit / combinational logic circuits, an input / output circuit and devices / input / output circuits and devices, a signal conditioning and buffer circuit and other components to provide a described functionality.Software, firmware, programs, instructions, control routines, code, algorithms, and similar terms refer to any set of instructions executable by a controller, including calibrations and lookup tables. Each controller executes a control routine(s) to provide desired functions, including monitoring inputs from sensing devices and other networked controllers and executing control and diagnostic routines to control the operation of actuators. Routines may be executed at regular intervals, e.g., every 100 microseconds or 3.125, 6.25, 12.5, 25, and 100 milliseconds, during continuous operation. Alternatively, routines may be executed in response to the occurrence of an event.Message transfers between controllers and between controllers, actuators, and / or sensors may be accomplished using a direct wired connection, a networked communication bus connection, a wireless connection, or any other suitable communication connection. Fixed-gear transmission 10 provides a non-limiting example of a transmission for the purpose of illustrating the concepts described herein. Other fixed-gear transmissions may employ the concepts described herein with similar effect.

[0018] The fixed-gear transmission 10 is dynamically monitored during operation, which includes monitoring transmission speeds, including an intermediate node speed, to dynamically detect the occurrence of a clutch lockup or other clutch failure and thus correct a change in torque, prevent or minimize a change in vehicle acceleration or deceleration, and avoid undesirable mechanical component stress that may reduce transmission life. This may include executing commands to adjust the engine torque input to the transmission 10, as well as other torque control commands.

[0019] Fig.2 schematically illustrates a clutch speed calculation routine 200 that includes a process for determining a clutch slip speed for one of the clutches based on a respective clutch slip speed relationship and dynamically monitored transmission speeds, including the transmission input speed, intermediate node speed, and transmission output speed. The clutch speed calculation routine 200 is advantageously applied to embodiments of fixed-gear transmission systems employing a plurality of planetary gear sets and will be described with reference to an embodiment of a nine-speed transmission 10 employing four planetary gear sets. Fig.1. The concepts of the clutch speed calculation routine 200 can be adapted for implementation with any fixed-gear transmission to calculate a speed at each of the nodes using information related to the mechanics of the transmission, as expressed in lever diagrams and related analytical tools and inputs from speed sensors. Table 2 is provided as a key, with the numbered blocks and corresponding functions exemplified as follows. Table 2 BLOCK BLOCK CONTENT 202 Derive node speed relationships for each gear set 204 Determined equivalent speed parameters for nodes of the planetary gear sets 206 Derive executable clutch slip speed relationship for each clutch based on the node speed relationships and the equivalent speed parameters 210 Monitor inputs from transmission speed sensors 212 Calculate clutch slip speeds using the executable clutch slip speed relationships and the monitored inputs from the transmission speed sensors and determine node speeds 214 Output clutch slip speeds, knot speeds

[0020] The clutch speed calculation routine 200 is applied to determine clutch slip speeds for the clutches of the transmission using equations defining mechanical relationships that are preferably derived offline and executed dynamically using dynamically monitored transmission speeds as follows.

[0021] A nodal speed relationship in the form of an equation for each of the planetary gear sets is derived based on the gear ratios (202). With reference to the gear arrangement configuration of transmission 10, which is described with reference to Fig. 1, there is a nodal speed relationship in the form of an equation for each of the first, second, third and fourth planetary gear sets 20, 30, 40 and 50.

[0022] The nodal speed equation for the first planetary gear set 20, which includes the output gear set having a tooth ratio of 83 / 37, the nominal ring gear / carrier gear ratio of 1.0, and the sun gear / carrier gear ratio of 2.24, is as follows: −b*NR1+(a+b)*NC1−a*NS1=0 where: a is the first sun gear / carrier gear ratio, which in this embodiment is 2.24; b is the first ring gear / carrier gear ratio, which in this embodiment is 1.0; N R1 is the rotational speed of the first ring gear 26; N C1 is the rotational speed of the first carrier wheel 24; and N S1 the speed of the first sun gear is 22.

[0023] The nodal speed equation for the second planetary gear set 30, which includes the input gear set having a tooth ratio of 83 / 37, a nominal ring gear / carrier gear ratio of 1.0, and a sun gear / carrier gear ratio of 2.24, is as follows: −d*NR2+(c+d)*NC2−c*NS1=0 where: c is the second sun gear / carrier gear ratio, which in this embodiment is 2.24; d is the second ring gear / carrier gear ratio, which in this embodiment is 1.0; N R2 is the rotational speed of the second ring gear 36; N C2 is the rotational speed of the second carrier wheel 34; and N S2 the speed of the second sun gear is 32.

[0024] The nodal speed equation for the third planetary gear set 40, which includes the reaction gear set having a tooth ratio of 74 / 25, a nominal ring gear / carrier gear ratio of 1.0, and a sun gear / carrier gear ratio of 2.96, is as follows: −f*NR3+(e+f)*NC3−e*NS3=0 where: e is the third sun gear / carrier gear ratio, which in this embodiment is 2.96; f is the third ring gear / carrier gear ratio, which in this embodiment is 1.0; N R3 is the rotational speed of the third ring gear 46; N C3 is the rotational speed of the third carrier wheel 44; and N S3 the speed of the third sun gear is 42.

[0025] The nodal speed equation for the fourth planetary gear set 50, which includes the overdrive gear set having a tooth ratio of 74 / 46, a nominal ring gear / carrier gear ratio of 1.0, and a sun gear / carrier gear ratio of 1.607: −h*NR4+(g+h)*NC4−g*NS4=0 where: g is the fourth sun gear / carrier gear ratio, which in this embodiment is 1.607; h is the fourth ring gear / carrier gear ratio, which in this embodiment is 1.0; N R4 is the rotational speed of the fourth ring gear 56; N C4 is the rotational speed of the fourth carrier wheel 54; and N S4 the speed of the fourth sun gear is 52.

[0026] Equivalent speed parameters are node speeds determined based on connections of the various nodes of the gear sets and the monitored nodes for the transmission 10, including the input node, the output node, and the monitored intermediate node (204). For example, equivalent speed parameters for the illustrated transmission 10 include: NR4=NR3=NC1=NO where N O is the speed of the output member 14, which is monitored by the output speed sensor 74. Other equivalent speed parameters for the illustrated transmission 10 include: NC4=NC3 and NS3=NIS where N IS the intermediate node speed, which is the speed of the third sun gear 42 of the third planetary gear set 40, monitored by the single intermediate node speed sensor 76, as shown.

[0027] An executable clutch slip speed equation is derived for each of the clutches based on the nodal speed equations and the equivalent speed parameters (206). This involves determining an initial clutch slip speed equation for each of the clutches based on the nodal speed equations for the planetary gear sets and the equivalent speed parameters. Each initial clutch slip speed equation is based on the speeds of the transmission nodes that are linked to each other when the respective clutch is fully activated and engaged. An example of an initial clutch slip speed equation includes the following: Nslip(C4)=NS4−NC3 where Nslip(C4) is the clutch slip speed for clutch C4, N S4 is the speed of the fourth sun gear 52, and N C3the speed of the third carrier gear 44 when the rotation of the fourth sun gear 52 is linked to the rotation of the third carrier gear 44 by activation of clutch C4. Initial clutch slip speed equations for the other clutches can be derived similarly.

[0028] For illustrative purposes, a derivation of an executable clutch slip speed equation for one of the clutches based on the nodal speed equations and the equivalent speed parameters will now be described, using clutch C4 as an example. Clutch C4 links components of the third and fourth planetary gear sets 40, 50 that have nodal speed equations that include equations 3 and 4 (above). The equivalent speed parameters are substituted into the nodal speed equations, which include, for example, equations 3 and 4, as follows: −f*NO+(e+f)*NC3−e*NIS=0 −h*NO+(g+h)*NC3−g*NS4=0

[0029] Equation 9 is calculated according to N C3 resolved as follows: NC3=(e*NIS+f*NO) / (f+e)

[0030] The resulting equation for N C3 , shown in Equation 11, is substituted in Equation 10 as follows. −h*NO+(g+h)*(e*NIS+f*NO) / (f+e)−g*NS4=0

[0031] The resulting equation shown in Equation 12 is solved for N S4 resolved as follows. NS4={−h*NO+(g+h)*(e*NIS+f*NO)*(f+e)} / g

[0032] The clutch slip for clutch C4 is determined as described in equation 8. The resultant for N C3 , which is shown in equation 11, and the resultant for N S4 shown in equation 13 are substituted into equation 8, resulting in the following equation. Nslip(C4)={−h*NO+(g+h)*(e*NIS+f*NIS) / (f+e)} / g−(e*NIS+f*NO) / (f+e)

[0033] Thus, the slip speed for clutch C4 can be calculated using monitored conditions that determine the intermediate node speed N IS and the output speed N O The execution of equation 14 can be reduced to algorithmic code that can be executed dynamically each time the intermediate node speed N IS and the output speed N O can be determined by monitoring. A person skilled in the art will be able to derive executable clutch slip speed equations for all clutches based on the nodal speed equations and the equivalent speed parameters using similar substitutions.

[0034] During dynamic operating conditions, signal outputs 209 from the transmission speed sensors are periodically monitored (210). The signal outputs 209 include, for the embodiment of the transmission 10 described with reference to Fig.1, the input speed sensor 72, which detects the input speed N I of the input element 12, the output speed sensor 74, which monitors the output speed N O of the output element 14, and the intermediate node speed sensor 76, which monitors the intermediate node speed N IS monitored, which is associated with the speed of the third sun gear 42 of the third planetary gear set 40. The clutch slip speed for each of the clutches is calculated based on the respective clutch slip speed equation and the monitored input transmission speed, the monitored intermediate node speed, and the monitored transmission output speed, and the node speeds are determined for all transmission nodes (212). The clutch slip speeds and the node speeds are made available for use by other control routines (214), including a transmission clutch slip speed monitoring routine 300, which is described with reference to Fig.3, and a transmission node overspeed monitoring routine 400 described with reference to Fig. 4 is described.

[0035] Fig. Figure 3 schematically shows an embodiment of a transmission clutch slip speed monitoring routine 300 that includes evaluating operation of each of the clutches of the transmission 10 based on the clutch slip speed to dynamically detect the occurrence of a clutch fault. This is performed using an embodiment of the transmission system 10 described above and the system described with reference to Fig. 2 is described. The concepts described herein can be applied to other transmission systems. Table 3 is provided as a key, with the numbered blocks and corresponding functions listed as follows. Table 3 BLOCK BLOCK CONTENT 300 start 302 Is unintended vehicle deceleration indicated (TRUE)? 304 Monitor gear command state for continuous operation (1) or switch to progressive operation (0) 306 Monitor unintended vehicle deceleration 308 Does unintended vehicle deceleration occur? 310 Unintended vehicle deceleration active 312 Unintended vehicle deceleration inactive 314 Determine release conditions, aborts, suspensions, triggering 315 Remedy for safe walking 316 Is surveillance approved? 320 Identify off-going clutch(es) = F(commanded gear) Identify on-coming clutch(es) = F(commanded gear) 322 Execute clutch blocking routine For clutch count i = 1 to n outgoing clutch(es) 324 Clutch (i) Operational test completed? 326 Determine conditions of the outgoing clutch 328 Are the conditions of the outgoing clutch met? 330 Slip speed of the off-going clutch (i) ≥ threshold exceeded? 332 Slip speed of the off-going clutch(i) ≤ minimum threshold? 334 Clutch operation test for off-going clutch(i) completed 336 Increment count i 338 Clutch count i completed? 340 Execute clutch neutral routine for clutch count j = 1 to m approaching clutch(es) 342 Clutch(j) Clutch operation test completed? 344 Determine conditions of the oncoming clutch 346 Are the conditions of the approaching clutch met? 348 Slip speed of the oncoming clutch(j) ≤ threshold exceeded? 350 Slip speed of the approaching clutch(j) ≥ ma- maximum threshold? 352 Determine clutch operation test completed for clutch(j) 354 Increment j 356 Count value approaching clutch = m= 360 End

[0036] The transmission clutch slip speed monitoring routine 300 is executed periodically, e.g., once every 100 microseconds, during continuous operation of the powertrain system. At each execution (300), a determination is made as to whether an "active" flag has been set, indicating that undesirable vehicle deceleration has been detected (302). If the "active" flag has not been set (302)(0), the transmission command state is monitored to determine whether the transmission is currently in steady-state operation (304)(1) or whether a transmission shift is in progress (304)(0). If the "active" flag has been set, indicating that undesirable vehicle deceleration has been detected (302)(1), or the transmission is currently in steady-state operation (304)(1), a control routine is executed to monitor undesirable vehicle deceleration (306).

[0037] The control routine for monitoring undesirable vehicle deceleration (306) includes monitoring clutch slip speeds for all clutches from the clutch speed calculation routine 200, an operator command for vehicle acceleration (305), sensor inputs including a vehicle longitudinal acceleration sensor (303), e.g., an accelerometer, and the output speed sensor to evaluate vehicle deceleration (306). The control routine is capable of correlating undesirable vehicle deceleration with undesirable clutch activation and deactivation by comparing the monitored clutch slip speeds with corresponding expected clutch slip speeds for each of the clutches.

[0038] The results of the control routine to monitor undesirable vehicle deceleration are evaluated (308), and if undesirable vehicle deceleration is detected (308)(1), an "undesirable vehicle deceleration active" flag is set (=TRUE) (312). A control routine is executed to remedy the situation and select an attainable gear state (315), and this iteration of the transmission clutch slip speed monitoring routine 300 ends (340).

[0039] Each time the clutch speed calculation routine 200 is applied in the transmission clutch slip speed monitoring routine 300, ie, at steps 306, 315, 330, 348 and 350, it is updated to dynamically provide a most recent calculation of the clutch speeds for subsequent use in executing the control routine based on newly collected data.

[0040] If no undesired vehicle deceleration is detected (308)(0) or if the system indicates that a transmission shift is in progress (304)(0), no undesired vehicle deceleration active flag is set (=FALSE)(310). In this case, enable criteria are monitored (314), which includes monitoring occurrences of shift aborts, shift misfires, and trips to determine that the clutch monitor is enabled (316). If it is not enabled (316)(0), this iteration ends without further action (340).

[0041] If enabled (316)(1), oncoming and offgoing clutches are identified for the commanded gear shift (320). A clutch lockup test is performed, which includes evaluating the speed of each of the offgoing clutches. This includes iteratively selecting and cycling through the offgoing clutches (322) for offgoing clutches indexed from i=1 to n. This includes evaluating the selected clutch to determine if it has completed a clutch operation test (324) and, if not (324)(0), determining clutch off-going conditions, e.g., occurrence of decreasing clutch pressure (326), and whether they are met (328). If the clutch off-going conditions are met (328)(1), the clutch slip speed for the selected clutch is evaluated to determine if the slip speed is greater than or equal to a passing slip speed threshold (330).If the slip speed is not greater than or equal to the passing slip speed threshold (330)(0), the clutch slip speed for the selected clutch is evaluated to determine if the slip speed is less than or equal to a minimum slip speed threshold (332). If the slip speed is greater than or equal to the passing slip speed threshold (330)(1), or if the slip speed is less than or equal to the minimum slip speed threshold (332)(1), the routine determines that the clutch operation test for the evaluated clutch is complete (334). If the clutch release conditions are not met (328)(0), or if the slip speed is not less than or equal to the minimum slip speed threshold (332)(0), a clutch release counter is indexed (336) and evaluated (338).If all off-going clutches have not been evaluated (338)(0), the routine loops again to perform the clutch lockup test for the next off-going clutch (steps 322 to 338). Otherwise (338)(1), the on-coming clutch(es) continue to be monitored.

[0042] The control routine to remedy the situation and select an achievable gear state includes monitoring the clutch slip speeds for all clutches from the clutch speed calculation routine 200 and evaluating the occurrence of intermittent neutral operation to isolate the location of a fault and select a safe gear for continued vehicle operation. This operation will now be described. The clutch neutral routine is executed for each oncoming clutch, with the oncoming clutches indexed from j = 1 to m (340). This includes evaluating the selected clutch to determine if it has completed a clutch operation test (342), and if not (342), determining clutch arrival conditions, e.g., an occurrence of increasing clutch pressure (344), to determine if they are met (346).If the clutch arrival conditions are met (346)(1), the clutch slip speed for the selected clutch is evaluated to determine if the slip speed is less than or equal to a passing slip speed threshold (348). If the slip speed is not less than or equal to the passing slip speed threshold (348)(0), the clutch slip speed for the selected clutch is evaluated to determine if the slip speed is greater than or equal to a maximum slip speed threshold (350). If the slip speed is less than or equal to the passing slip speed threshold (348)(1), or if the slip speed is greater than or equal to the maximum slip speed threshold (350)(1), the routine determines that the clutch operation test for the evaluated clutch is complete (352).If the clutch arrival conditions are not met (346)(0) or if the slip speed is not greater than or equal to the maximum slip speed threshold (350)(0), a clutch arrival counter is indexed (354) and evaluated (356). If all off-going clutches have not been evaluated (356)(0), the routine loops again to perform the clutch neutral test for the next on-coming clutch (steps 342 through 354). This iteration of the transmission clutch slip speed monitoring routine 300 ends (360).

[0043] The transmission clutch slip speed monitoring routine 300 provides transmission internal component overspeed protection and clutch capacitance fault detection using transmission node speeds and clutch slip speeds, which includes a dynamic-based approach to detecting node overspeed conditions that may cause transmission faults. Node speeds are calculated based on transmission component design and dynamically updated and monitored to immediately trigger transmission component protection, which includes the use of engine torque control and / or engine speed control to prevent transmission component faults when triggered by detecting overspeed conditions at one or more transmission nodes. Fault detection includes detecting hydraulic circuit faults, clutch control solenoid faults, and / or clutch mechanical faults.Such operation also enables a reduction in the complexity and calibration of diagnostic algorithms. Dynamic monitoring and detection is performed during shift events and steady-state gear operation, including during shift sequence points, to evaluate gear ratio / slip for jam detection, providing immediate assessment and decision for jam detection and remediation. This configuration delivers and achieves a result during a single shift event using node speeds and individual clutch slip speeds, thereby increasing reliability and system robustness.

[0044] Fig.4 schematically illustrates an embodiment of a transmission node overspeed monitoring routine 400 including a process for detecting an occurrence of a node overspeed condition and taking remedial action in response thereto. This is performed using an embodiment of the transmission system 10 described above and the method described with reference to Fig. 2. The concepts described herein may be applied to other transmission systems.

[0045] Table 4 is given as a key, with the blocks marked with numbers and the corresponding functions listed as follows. Table 4 BLOCK BLOCK CONTENT 410 Determine knot speeds 412 Is knot speed greater than threshold A? 414 Perform engine speed limit operation 416 Is knot speed greater than threshold B? 418 Is knot speed less than threshold C? 420 Continue engine speed limit operation 422 Is knot speed less than threshold C and has a DND range change occurred? 424 End

[0046] The transmission node overspeed monitoring routine 400 periodically determines the node speeds for the nodes of the transmission using the node speed equations described herein for the embodiment of the transmission 10 as part of the clutch speed calculation routine 200 (410). A plurality of node speed thresholds for each node of the transmission are determined, examples of which are shown graphically, including speed (RPM) 404 shown relative to time 402, with speed thresholds including threshold A 403, threshold B 401, and threshold C 405. Threshold A 403 is a nominal node speed, threshold B 401 is an upper node speed associated with an increasing speed condition, and threshold C 405 is a lower node speed associated with a decreasing speed condition.

[0047] The node speed is compared to threshold A (412). If the node speed exceeds threshold A (412)(1), the transmission issues an engine speed request to limit a transmission input speed condition, ie, the engine speed, to or less than a calibrated speed that is less than the engine speed at which the node exceeded threshold A (414). Otherwise (412)(0), this iteration of routine 400 ends (424).

[0048] The node speed continues to be monitored and updated and compared to threshold B (416). If the node speed is less than threshold B (416)(0), the routine compares the node speed to threshold C (418). If the node speed continues to be greater than threshold C (418)(0), the transmission continues to issue the engine speed request to limit the transmission input speed state to or less than a calibrated speed that is less than the engine speed at which the node exceeded threshold A (414). If the node speed decreases to less than threshold C (418)(1), this iteration ends (424). If the node speed is greater than threshold B (416)(1), the transmission continues to issue the engine speed request.The transmission also commands the transmission to assume neutral and deactivate all clutches to free the transmission case of any induced inertia and load. Remedial strategies are executed to reduce engine speed and thus transition transmission operation to a safe gear state (420). The node speed threshold is compared to threshold C, and the remedial strategies continue to execute as long as the node speed threshold is greater than threshold C and a transmission range change, including a drive-neutral-drive range change, has occurred (422)(0). Otherwise (422)(1), this iteration ends (424). Thus, by applying the calculated node speed to the transmission, the system is able to monitor, detect, and remediate overspeed conditions.

Claims

[1] A method (200) for monitoring a fixed-gear transmission (10) comprising a plurality of interconnected planetary gear sets (20, 30, 40, 50) and a plurality of selectively activatable clutches (CB1R 61, CB38 62, C57R 63, C6789 64, CB123456 65, C4 66, CB29 67) during operation, the method (200) comprising: Deriving a node speed relationship (equations 1, 2, 3, 4) for each of the planetary gear sets (20, 30, 40, 50) based on gear ratios of the corresponding planetary gear set (20, 30, 40, 50) (202); Determining equivalent speed parameters for nodes of the planetary gear sets (20, 30, 40, 50) based on a transmission input speed, an intermediate node speed and a transmission output speed (204); Determining a clutch slip speed relationship (equation 8) for each of the clutches (CB1R 61, CB38 62, C57R 63, C6789 64, CB123456 65, C4 66, CB29 67) based on the nodal speed relationships for the planetary gear sets (20, 30, 40, 50) and the equivalent speed parameters for the nodes of the planetary gear sets (20, 30, 40, 50) (206); dynamic monitoring, via speed sensors (72, 74, 76), of the transmission input speed (N I ), the intermediate node speed (N IS ) and the transmission output speed (N O )(210); and Calculating (Equation 14) a clutch slip speed (Nslip(C4)) for each of the clutches (20, 30, 40, 50) based on the respective clutch slip speed relationship (Equation 8) and the dynamically monitored transmission input speed (N I ), intermediate node speed (N IS ) and transmission output speed (N O )(212). [2] The method (200) of claim 1, wherein deriving a node speed relationship (equations 1, 2, 3, 4) for each of the planetary gear sets (20, 30, 40, 50) based on gear ratios of the respective planetary gear set (20, 30, 40, 50)(202) comprises deriving a node speed relationship (equations 1, 2, 3, 4) based on a ring gear / carrier gear ratio (b, d, f, h), a sun gear / carrier gear ratio (a, c, d, f) and speeds (N R1 , N R2 , N R3 , N R4 , N C1 , N C2 , N C3 , N C4 , N S1 , N S2 , N S3 , N S4 ) of the ring gear (26, 36, 46, 56), the carrier (24, 34, 44, 54) and the sun gear (22, 32, 42, 52) for the planetary gear set (20, 30, 40, 50). [3] Method (200) according to claim 1, wherein the dynamic monitoring, via speed sensors (72, 74, 76), of the transmission input speed (N I), the intermediate node speed (N IS ) and the transmission output speed (N O )(210) periodically monitoring signal outputs from the speed sensors (72, 74, 76) corresponding to the monitored transmission input speed (N I ), the intermediate node speed (N IS ) and the transmission output speed (N O ) during continuous transmission operation. [4] The method (200) of claim 1, further comprising calculating a node speed for each of the nodes of the planetary gear sets (20, 30, 40, 50) based on the dynamically monitored input transmission speed (N I ), intermediate node speed (N IS ) and transmission output speed (N O ), the node speed relationships (equations 1, 2, 3, 4) for the planetary gear sets (20, 30, 40, 50) and the equivalent speed parameters for the nodes of the planetary gear sets (20, 30, 40, 50). [5] The method (200) of claim 4, further comprising executing a node overspeed detection routine (400) based on the calculated node speed for each of the nodes of the planetary gear sets (20, 30, 40, 50). [6] The method (200) of claim 5, further comprising detecting a node overspeed condition when the calculated node speed for one of the nodes exceeds a threshold (412), and limiting the transmission input speed (N I ) on the basis of this (414). [7] The method of (200) claim 1, further comprising detecting (300) a clutch fault for one of the clutches (CB1R 61, CB38 62, C57R 63, C6789 64, CB123456 65, C4 66, CB29 67) based on the corresponding calculated clutch slip speed. [8] The method (200) of claim 7, wherein detecting a clutch fault for one of the clutches (CB1R 61, CB38 62, C57R 63, C6789 64, CB123456 65, C4 66, CB29 67) based on the corresponding calculated clutch slip speed (300) comprises detecting a clutch lock-up for one of the clutches (CB1R 61, CB38 62, C57R 63, C6789 64, CB123456 65, C4 66, CB29 67) when the calculated clutch slip speed for the clutch is less than a threshold slip speed (322-338). [9] The method (200) of claim 7, wherein detecting a clutch fault for one of the clutches (CB1R 61, CB38 62, C57R 63, C6789 64, CB123456 65, C4 66, CB29 67) based on the corresponding calculated clutch slip speed (300) comprises detecting a clutch neutral state for one of the clutches (CB1R 61, CB38 62, C57R 63, C6789 64, CB123456 65, C4 66, CB29 67) when the calculated clutch slip speed for the clutch is greater than a threshold slip speed (340-360). [10] A method (200) for monitoring a fixed gear transmission (10) of a drive train system comprising a plurality of planetary gear sets (20, 30, 40, 50) and a plurality of clutches, the method (200) comprising: Deriving a nodal speed relationship (equations 1, 2, 3, 4) for each of the planetary gear sets (20, 30, 40, 50)(202); Determining equivalent speed parameters for nodes of the planetary gear sets (20, 30, 40, 50) on the basis of a transmission input speed (N I ), at least one intermediate node speed (N IS ) and a transmission output speed (N O )(204); Determining a clutch slip speed relationship (Equation 8) for each of the clutches (CB1R 61, CB38 62, C57R 63, C6789 64, CB123456 65, C4 66, CB29 67) based on the nodal speed relationships for the planetary gear sets (20, 30, 40, 50) and the equivalent speed parameters for the nodes of the planetary gear sets (20, 30, 40, 50)(206); dynamic monitoring, via speed sensors (72, 74, 76), of the transmission input speed (N I ), which has at least one intermediate node speed (N IS ) and the transmission output speed (N O )(210); and Calculate a clutch slip speed (Nslip(C4)) for each of the clutches (CB1R 61, CB38 62, C57R 63, C6789 64, CB123456 65, C4 66, CB29 67) based on the respective clutch slip speed relationship (Equation 8) and the dynamically monitored transmission input speed (N I ), which has at least one intermediate node speed (N IS ) and the transmission output speed (N O )(212).

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