Systems for cleaning clutch valves

Abstract

System that includes: a gearbox configured to rotatably couple a drive motor to a drive shaft; a first input shaft that is coupled to the gearbox; a second input shaft that is coupled to the gearbox; a dual clutch arrangement comprising a first clutch mechanism and a second clutch mechanism, wherein the first clutch mechanism and the second clutch mechanism selectively couple the first input shaft or the second input shaft to the drive machine in response to a clutch pressure request; a valve configured to control the flow of hydraulic fluid to the dual-clutch assembly; and a controller containing non-volatile instructions stored in memory, which can be executed to do the following: Sending a valve cleaning control pulse to the valve in response to the detection that the first clutch mechanism or the second clutch mechanism has remained in an engaged position for a first threshold duration and the clutch pressure request is within a threshold pressure range; and Interrupting the valve cleaning control pulse in response to the detection of at least one abort condition.

Description

TECHNICAL FIELD

[0001] This description relates generally to hydraulic actuation systems and, more particularly, to systems for reducing the accumulation of contaminants in a clutch valve during extended period of operation of the clutch valve. BACKGROUND AND SUMMARY

[0002] In hydraulic clutch actuation systems, contaminants such as sludge and deposits can accumulate in a valve spool under certain conditions, such as when the valve position remains constant for an extended period or when the valve experiences low flow for an extended period. Previous valve cleaning strategies involve cleaning the valve with the clutch disengaged, typically at the beginning or end of a drive cycle.

[0003] However, the inventors have identified potential problems with such systems. For example, the clutch valve may operate for extended periods without cleaning, especially when the vehicle is under steady operating conditions, such as idling or highway driving. When the clutch is engaged and the clutch valve's range of motion is limited, oil flow around the valve spool stagnates. Low oil flow, restricted clutch valve movement, and infrequent cleaning cycles increase the risk of contaminant deposition or sludge buildup, which can impair clutch performance over time.

[0004] In one example, the problems described above may be addressed by a valve cleaning method comprising sending a valve cleaning control pulse to a valve in response to a clutch remaining in an engaged position and a clutch pressure request being within a threshold pressure range, and interrupting the valve cleaning control pulse in response to detecting at least one abort condition. In this way, the clutch valve is cleaned during the drive cycle.

[0005] In one example, the at least one abort condition includes an expected clutch disengagement and / or a clutch pressure request outside the threshold pressure range. The valve cleaning control pulse for cleaning the valve may include cycling the valve for a threshold duration. In one example, the valve cleaning control pulse comprises cycling the valve pressure between a first threshold value and a second threshold value for a first threshold duration. The cyclical pressure change of the valve moves the valve spool up and down at a high speed, creating a jarring effect that can dislodge contaminants. The action may also increase the oil flow rate through the valve, thereby reducing the risk of contaminants in the oil accumulating in or around the valve spool. In this way, the clutch is cleaned under conditions where sludge buildup is most likely.

[0006] It should be understood that the above summary is intended to introduce, in simplified form, a selection of concepts that are further explained in the detailed description. It is not intended to identify the most important or essential features of the claimed subject matter, the scope of which is clearly defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that address the disadvantages noted above or elsewhere in this disclosure. SHORT DESCRIPTION OF THE CHARACTERS Fig. 1 shows a schematic representation of a vehicle with a powertrain that includes a transmission system. Fig. 2 shows a state machine illustrating a clutch cleaning model in which transitions from a first state to a second state may be based on a clutch cleaning status and one or more sensor signals. Fig. Figure 3 shows a flow chart illustrating an exemplary method for cleaning a closed clutch. Fig. Figure 4 shows timing diagrams illustrating an example of the prophetic operation of a closed clutch cleaning method. DETAILED DESCRIPTION

[0007] The following description relates to systems and methods for cleaning a valve of a clutch. In one example, the valve may be a spool valve that controls the engagement of the clutches in a dual-clutch transmission. In one example, a valve control strategy is proposed in which the valve is switched in a sawtooth pattern when the clutch is in lock-up torque control. In one example, lock-up torque control is a clutch engagement condition in which clutch torque is demanded above the current engine torque to ensure that slippage does not occur. The cleaning process terminates when clutch pressure falls outside a specified range, a component failure is detected, or oil pressure or line pressure falls below or above thresholds.The valve's sawtooth oscillation moves the valve spool up and down at high speed, creating a jiggling effect that can dislodge contaminants and increase the flow rate through the spool, reducing the risk of "sludge," in which deposits in the oil build up in or around the piston and cause seizure. An example vehicle 100 with a dual-clutch transmission is shown in . Fig. 1. A state diagram illustrating an exemplary state machine 200 for controlling a clutch cleaning system to execute one or more exemplary clutch cleaning routines in a vehicle is shown in Fig. 2 shown. Fig. 3 is a flowchart showing an exemplary method for controlling a clutch cleaning system. Fig. Figure 4 shows timing diagrams illustrating prophetic examples of the disclosed methods for cleaning a closed clutch.

[0008] Fig. 1 shows a schematic representation of a vehicle 100 having a powertrain 102 including a transmission system 104 with a multi-speed transmission 106. The vehicle may take different forms in various embodiments, e.g., a light, medium, or heavy-duty commercial vehicle for both on-road and off-road use. The powertrain 102, in particular the transmission system 104, includes a prime mover, which may be an internal combustion engine 110 (e.g., a gasoline and / or compression-ignition engine, a hydrogen combustion engine, and the like). However, in other examples, the powertrain 102 may be adapted for use in a hybrid vehicle, in which the powertrain 102 includes an internal combustion engine and an electric machine (e.g., a traction motor such as a motor-generator).The internal combustion engine 110 may include conventional components such as cylinders, pistons, valves, a fuel delivery system, an intake system, an exhaust system, and the like.

[0009] The transmission system 104 is illustrated as a dual-clutch transmission including a dual-clutch assembly 118 described in more detail herein, although automated manual transmissions, manual transmissions, and pure internal combustion engine transmissions are also contemplated and described in more detail herein. Therefore, the dual-clutch assembly 118 may be generally referred to as a dual clutch. In other examples, the transmission system 104 may be included in a transaxle unit that includes an axle 120, a differential 122, and the transmission system 104 in a single unit. In this way, the transmission may be adapted for use in a mid-engine or front-engine vehicle. However, in other examples, the transmission, axle, and / or differential may be packaged as separate units.

[0010] The transmission system 104 includes the multi-speed transmission 106, which is configured to shift between various discrete operating gears. The multi-speed transmission 106 may be configured to transmit torque to the drive wheels 124 via the differential 122 (e.g., the axle differential). Specifically, an output shaft 126 (e.g., pinion shaft) having a bevel gear 128 (e.g., bevel pinion gear) meshing with a bevel gear 130 (e.g., ring gear) connected to the differential case (or carrier) 132 may be used to provide the mechanical connection between the transmission and the differential, although other suitable gear types may be used in other examples. In one example, the output shaft 126 may be a driveshaft. However, other suitable types of mechanical attachments may also be used to connect the transmission to the differential.Furthermore, an intermediate gear 127 may be fixedly connected to the output shaft 126 (e.g., by spline engagement, a welded connection, other suitable connections, or combinations thereof) and mesh with an output gear (not shown) of the multi-speed transmission 106. The drive gears 124 may be rotatably coupled to the differential via axle shafts 134 and / or other suitable mechanical components. The rotational axes of the axle shafts 134 may be arranged perpendicular to the rotational axes of the internal combustion engine 110, a first input shaft 140, a second input shaft 142, and / or the output shaft 126. Such a design of the transmission system may enable the system to be efficiently installed in the vehicle and, in some cases, used in a larger number of vehicles.However, in alternative examples, the axle shafts may be arranged parallel to the internal combustion engine 110, a first input shaft 140, the second input shaft 142, and / or the output shaft 126. Furthermore, the differential 122 may be an open differential, an electronic limited-slip differential, a mechanical limited-slip differential, and the like.

[0011] The internal combustion engine 110 may include an output shaft 136 that may be rotatably coupled to the dual clutch assembly 118 in the transmission system 104. Furthermore, the dual clutch assembly 118 may selectively rotatably couple the output shaft 136 to a first input shaft 140 and a second input shaft 142. The first input shaft 140 may be an inner shaft, and the second input shaft may be an outer input shaft and coaxial with the first input shaft. For illustration, the second input shaft 142 may be hollow and arranged concentrically around the first input shaft 140, or vice versa. In alternative embodiments, the dual clutch assembly may be replaced with a single clutch assembly for use in a manual transmission or an automated manual transmission, as further explained herein.

[0012] The dual clutch assembly 118 may include a first clutch mechanism 143 and a second clutch mechanism 144, which may be wet or dry friction clutches. The first clutch mechanism 143 may include discs (e.g., friction discs and / or intermediate plates), and in some cases, springs, that can be engaged to transfer torque from the output shaft 136 to the first input shaft 140. Thus, when the first clutch mechanism 143 is engaged, the output shaft 136 transfers torque to the first input shaft 140. Conversely, when the first clutch mechanism 143 is disengaged, the mechanical power transmission through the clutch mechanism is inhibited. Similarly, the second clutch mechanism 144 may include discs (e.g.,Friction plates and / or intermediate plates), and in some cases, springs, that can be engaged to transfer torque from the output shaft 136 to the second input shaft 142. Thus, when the second clutch mechanism is engaged, the output shaft 136 transfers torque to the second input shaft, and when the second clutch mechanism is disengaged, the second clutch mechanism prevents torque transmission. If the transmission system includes a dual-clutch arrangement, it may be referred to as a dual-clutch transmission system in one example.

[0013] In one example, the dual clutch assembly 118 includes a clutch actuator system with a spool valve, schematically illustrated and hereinafter referred to as clutch actuator system 154. In one example, the spool valve of the clutch actuator system 154 is housed in a housing. The position of the spool valve within the housing can determine which of the first clutch mechanism 143 and the second clutch mechanism 144 is engaged or disengaged. The clutch actuator system 154 uses hydraulic fluid contained within a schematically illustrated hydraulic system 150. The hydraulic system 150 can include one or more pumps to pressurize hydraulic fluid in a plurality of lines, schematically illustrated and hereinafter referred to as lines 152.The position of the spool valve can be controlled by the clutch actuator system 154 in coordination with a controller 191 and the hydraulic system 150. For example, if an adjustment of the first clutch mechanism 143 or the second clutch mechanism 144 is desired, the controller 191 sends a control signal to the clutch actuator system 154. The clutch actuator system 154 then adjusts the position of the spool valve based on the control signal. The position of the spool valve directs pressurized hydraulic fluid via lines 152 to a desired location in the clutch actuator system 154 to engage or disengage the selected clutch.

[0014] The multi-speed transmission 106 may further include an additional shaft (not shown). The gear sets may be located on the first input shaft 140, the second input shaft 142, or the additional shaft, respectively. Each of the gear sets may include multiple gears. For example, one or more gear sets on the first input shaft 140 and one or more gear sets on the second input shaft may mesh with a portion of the gears located on the additional shaft. In some examples, the gears located on the additional shaft that mesh with the gears on the first input shaft 140 may be referred to as odd gears. The gears located on the additional shaft that mesh with the gears on or coaxial with the second input shaft 142 may be referred to as even gears.For example, by engaging the first clutch mechanism 143, the internal combustion engine 110 is selectively coupled to the first input shaft 140 and one or more of the odd gears meshing therewith. By selectively engaging the second clutch mechanism 144, the internal combustion engine 110 is selectively connected to the second input shaft 142 and one or more of the even gears meshing therewith.

[0015] Vehicle 100 may further include a control system 190 with controller 191. Controller 191 includes a processor 192 and memory 193. Memory 193 may store non-transitory instructions that, when executed by the processor, cause controller 191 to perform the various methods, control techniques, etc., described herein. Processor 192 may include a microprocessor unit and / or other types of circuitry. Memory 193 may include known data storage media such as random access memory, read-only memory, diagnostic memory, combinations thereof, and the like.

[0016] The controller 191 may receive various signals from sensors 194 (e.g., speed sensors, pressure sensors, clutch configuration sensors, temperature sensors, and the like) located within the vehicle 100 (e.g., within the powertrain 102 and, in particular, within the transmission system 104). Conversely, based on the received signals and the instructions stored in the memory 193 of the controller 191, the controller 191 may send control signals to various actuators 195 at various locations within the vehicle and transmission system, e.g., for engaging the clutch, shifting, actuating the electronic differential, and the like. For example, the controller 191 may send command signals to the dual clutch assembly 118 and / or the clutch actuator system 154.When the dual-clutch assembly 118 receives the command signal, the clutch actuator system 154 can be used to place the clutch in its engaged position, for example, by adjusting the position of the spool valve or other suitable clutch valve. The other controllable components of the transmission, such as an electric pump, solenoid valves, and the like, and more generally of the vehicle, can be operated in a similar manner with respect to the sensor signals and the adjustment of the actuators. Components that can be adjusted by the controller 191 can include the internal combustion engine 110, the differential 122 in the case of an electronic limited-slip differential, other external devices / accessories such as an air braking system and a suspension system, and the like. However, in other examples, at least some of these controllable components can be adjusted with separate controllers.

[0017] Furthermore, the controller 191 may be configured to execute commands to clean a clutch valve, such as the spool valve of the clutch actuator system 154, as will be explained in more detail herein. For example, the controller 191 may operate a clutch valve cleaning system, including adjusting the hydraulic fluid to the clutch actuator system 154 via the hydraulic system 150 during the execution of one or more clutch cleaning operations. The clutch cleaning system may, for example, include a plurality of clutch cleaning routines that are executed in response to one or more operating conditions, such as routines that are executed when the clutch is disengaged or engaged, and / or in response to conditions such as degraded shift quality, slippage, wear, and other faults. Example clutch cleaning routines are described below with reference to Fig. 2-5 described.

[0018] The control system 190 may also include one or more input devices 196. The input devices 196 may include a gear selector that allows the vehicle operator to select an active gear from a group of drive ratios and / or a forward, reverse, and neutral drive mode. The input devices 196 may further include a transmission system operating mode selector that allows the operator to select the current operating mode of the vehicle from a group of operating modes. However, in other examples, the transmission system may utilize more automated techniques for gear and / or drive mode selection.

[0019] Fig. 2 shows a state diagram of an exemplary state machine 200 representing a clutch cleaning system for a vehicle, as described with reference to the vehicle 100 of Fig. 1. The state machine 200 may use a control system such as the control system 190 of Fig. 1, as well as signals from sensors and / or actuators of the vehicle system, as described with reference to Fig. 1. For example, the clutch cleaning system may include a plurality of clutch cleaning methods programmed as instructions in memory 193 of controller 191 of control system 190 and executed by processor 192 in response to one or more operating states. The clutch cleaning system described by state machine 200 transitions between an idle state, a closed cleaning state, an open cleaning state, a routine cleaning state, and a valve purge state. In the idle state, no clutch cleaning occurs. In the open cleaning state, an open clutch cleaning operation may be performed by the clutch cleaning system. In the valve purge state, a valve purge operation may be performed by the clutch cleaning system. In the routine cleaning state, a routine cleaning operation may be performed by the clutch cleaning system.In the closed cleaning state, a closed clutch cleaning process can be performed by the clutch cleaning system. Example cleaning procedures with the clutch closed are described below with reference to . Fig. 3-4. State machine 200 may transition from one state to another based on sensor signals and / or actuators indicating one or more operating conditions, such as a condition that exceeds a threshold.

[0020] The clutch cleaning system may be considered to be operating in the idle state when the clutch cleaning system is operating with standard operating parameters, referred to herein as idle mode 201. Idle mode 201 may include all standard and typical behaviors of the vehicle system. In one example, idle mode 201 includes the valve position not oscillating. The clutch cleaning system may transition from idle mode 201 to the open cleaning state, referred to herein as active open cleaning mode 206, based on the detected disengagement of a clutch, represented by arrow 226. For example, disengagement of one of the first clutch mechanism 143 and the second clutch mechanism 144 of the dual clutch assembly 118 in the vehicle 100 may cause the state machine 200 to transition from idle mode 201 to the active open cleaning mode 206.In one example, state machine 200 may transition from idle mode 201 to active open purge mode 206 when the hydraulic pressure applied to the clutch during disengagement is reduced or released. For example, in idle mode 201, if the clutch pressure drops below a non-zero threshold pressure (e.g., 5 bar) and a pressure drop is requested in the system, this may trigger the transition to active open purge mode 206.

[0021] The clutch cleaning system may be considered to be operating in the active open cleaning mode 206 when the clutch cleaning system performs the open cleaning operation. In one example, the open cleaning operation may include rapidly cyclically decreasing and increasing the valve pressure to relieve line pressure and clean the valve, also referred to herein as cycling. For example, the open cleaning operation may include increasing the valve pressure to an upper threshold for a first duration (e.g., 19 bar for 0.1 seconds) and then reducing the valve pressure to a lower threshold (e.g., 0.1 bar for 0.1 seconds) and repeating the cycle for a duration (e.g., 0.5 seconds).The clutch cleaning system may transition from the active open cleaning mode 206 to a completed open cleaning mode 208 based on the detected completion of the open cleaning operation, represented by arrow 228. For example, an indication that hunting exceeds a threshold duration (e.g., 0.5 seconds) may cause the state machine 200 to transition from the active open cleaning mode 206 to the completed open cleaning mode 208. The clutch cleaning system may transition from the active open cleaning mode 206 to the idle mode 201 if an incomplete open cleaning operation is detected, represented by arrow 232. For example, the open cleaning operation may include one or more conditions that trigger an abort of the operation. One such condition may be an indication of clutch engagement.For example, an indication that clutch engagement exceeds a threshold duration (e.g., 0.5 seconds) prior to hunting may cause state machine 200 to transition from active open purge mode 206 to idle mode 201. Other conditions may include an indication of a component failure or an operating condition where pressure is exceeded, undershot, or hydraulic fluid temperature is exceeded.

[0022] The clutch cleaning system may be considered to be operating in the completed open cleaning mode 208 when the clutch cleaning system has completed the open cleaning operation. The clutch cleaning system may transition from the completed open cleaning mode 208 to the idle mode 201, represented by arrow 230. In one example, the clutch cleaning system may transition from the completed open cleaning mode 208 to the idle mode 201 when the open cleaning operation reaches an open cleaning time threshold or a calibrated percentage of the open cleaning time threshold has elapsed and a cleaning abort request is triggered.

[0023] The clutch cleaning system may transition from idle mode 201 to the routine cleaning state, referred to herein as active routine cleaning mode 210, based on a detected clutch cleaning system request for routine cleaning by the universal diagnostic system (UDS), represented by arrow 234. In some examples, routine cleaning may be requested at regular intervals, such as as part of a standard operating procedure. In other examples, routine cleaning may be requested when operating conditions exceed or fall below a threshold. In most examples, routine cleaning is invoked by the UDS routine called by the respective UDS tool.For example, routine cleaning of the clutch cleaning system may cause state machine 200 to transition from idle mode 201 to active routine cleaning mode 210 in response to a stuck valve indication.

[0024] The clutch cleaning system may be considered to be operating in the active routine cleaning mode 210 when the clutch cleaning system is performing a routine cleaning. In one example, the routine cleaning may be the same or a similar operation as the open cleaning operation, including cycling the valve between 0 and 19 bar to release a stuck valve. Likewise, as above, the routine cleaning may include increasing the valve pressure to an upper threshold for a first duration (e.g., 19 bar for 0.1 seconds) and then reducing the valve pressure to a lower threshold (e.g., 0.1 bar for 0.1 seconds) and repeating the cycle for a duration (e.g., 0.5 seconds). The clutch cleaning system may transition from the active routine cleaning mode 210 to the completed routine cleaning mode 212 based on the detected completion of the routine cleaning, represented by arrow 236.For example, an indication that hunting exceeds a threshold duration (e.g., 0.5 seconds) may cause state machine 200 to transition from active routine cleaning mode 210 to completed routine cleaning mode 212. The clutch cleaning system may transition from active routine cleaning mode 210 to idle mode 201 if incomplete routine cleaning is detected, represented by arrow 240. For example, routine cleaning may include one or more conditions that trigger an abort of the operation. One such condition may be the indication of a component failure or operating condition that exceeds or falls below a threshold, such as abnormal line pressure or abnormal hydraulic fluid temperature.

[0025] The clutch cleaning system may be considered to be operating in the completed routine cleaning mode 212 when the clutch cleaning system has completed the routine cleaning. The clutch cleaning system may transition from the completed routine cleaning mode 212 to the idle mode 201, represented by arrow 238. In one example, the clutch cleaning system may transition from the completed routine cleaning mode 212 to the idle mode 201 when the routine cleaning operation reaches a routine cleaning time threshold without a cancel request.

[0026] The clutch cleaning system may transition from idle mode 201 to the valve purge state, referred to herein as active valve purge mode 214, based on a detected clutch cleaning system request for valve purge, represented by arrow 242. In some examples, valve purge may be requested at regular intervals, such as as part of a standard operating procedure. Further, valve purge may be requested when operating conditions exceed or fall below a threshold. For example, valve purge may be requested when the valve is in a pre-fill or standard state, i.e., not controlling hydraulic fluid flow, for longer than a threshold duration. In one example, valve purge may be requested to remove sludge and reduce valve sticking.For example, the clutch cleaning system may cause the state machine 200 to transition from the idle mode 201 to the active valve purge mode 214 in response to a stuck valve indication.

[0027] The clutch cleaning system can be considered to be operating in active valve purge mode 214 when the clutch cleaning system is performing a valve purge. In one example, valve purge may include increasing the amplitude of a valve dither and decreasing the dither frequency to temporarily increase lift and spool force. In some examples, valve purge may be used as a less aggressive means to reduce the risk of valve sludge buildup and to loosen a potentially stuck valve. Because it only changes the dither and not the actual effective current, it can be used in clutch control without overly affecting pressure response. As previously mentioned, it is not as aggressive and effective at removing sludge or deposits as valve cleaning.The clutch cleaning system may transition from the active valve purge mode 214 to a completed valve purge mode 216 based on the detected completion of the valve purge process, represented by arrow 244. For example, an indication that the valve purge exceeds a threshold duration (e.g., 0.5 seconds) may cause the state machine 200 to transition from the active valve purge mode 214 to the completed valve purge mode 216. The clutch cleaning system may transition from the active open valve purge mode 214 to the idle mode 201 if an incomplete open valve purge process is detected, represented by arrow 248. For example, the valve purge process may include one or more conditions that trigger an abort of the process. One such condition may be an indication of a component failure or operating condition that exceeds or falls below a threshold, e.g.,an abnormal line pressure or an abnormal hydraulic fluid temperature.

[0028] The clutch cleaning system may be considered to be operating in the completed valve purge mode 216 when the clutch cleaning system has completed the valve purge process. The clutch cleaning system may transition from the completed valve purge mode 216 to the idle mode 201, represented by arrow 246. In one example, the clutch cleaning system may transition from the completed valve purge mode 216 to the idle mode 201 when the valve purge process reaches a valve purge time threshold or a calibrated percentage of the valve purge time threshold has elapsed and a purge abort request is triggered.

[0029] The clutch cleaning system may transition from idle mode 201 to the closed cleaning state, referred to herein as active open cleaning mode 202, based on detected clutch engagement and a clutch pressure request within a target range, represented by arrow 218. The clutch pressure target range may, for example, be a pressure calibrated to maintain clutch torque above the current engine torque request to avoid slippage. For example, the clutch pressure target value is set well above the pressure required to maintain the usual operating (micro)slip range. The (micro)slip range may, for example, be a clutch pressure equivalent to maintaining a clutch torque request 25 revolutions per minute (RPM) above engine torque.In other words, the closed active purge mode 202 may be requested for a specific duration in response to a detected clutch engagement in the lock-up torque control. For example, engaging the first clutch mechanism 143 or the second clutch mechanism 144 of the dual clutch assembly 118 in the vehicle 100 for a duration greater than a threshold and within the target pressure range may cause the state machine 200 to transition from the idle mode 201 to the active closed purge mode 202.

[0030] The clutch cleaning system may be determined to be operating in the active closed-loop cleaning mode 202 when the clutch cleaning system performs the closed-loop cleaning operation. In one example, the closed-loop cleaning operation may include a clutch cleaning operation that includes rapidly cyclically decreasing and increasing the valve pressure, e.g., cycling, within an upper and lower threshold based on the clutch pressure request from the torque-to-pressure controller. For example, the closed-loop cleaning operation may include setting the valve pressure to a first threshold pressure for a first duration, then to a second threshold pressure for a second duration, and repeating the cycle for a third threshold duration.In one example, the first threshold pressure is different from the second threshold pressure, the first duration is equal to or different from the second duration, and the third threshold duration is greater than the first duration and the second duration. The clutch cleaning system may transition from the active closed cleaning mode 202 to a completed closed cleaning mode 204 based on the detected completion of the closed cleaning operation, represented by arrow 220. For example, an indication that hunting exceeds the first threshold duration (e.g., 0.5 seconds) may cause the state machine 200 to transition from the active closed cleaning mode 202 to the completed closed cleaning mode 204.The clutch cleaning system may transition from the active closed-loop cleaning mode 202 to the idle mode 201 when an incomplete closed-loop cleaning operation is detected, represented by arrow 222. For example, the closed-loop cleaning operation may include one or more conditions that trigger an abort of the operation. Conditions include, for example, the expected clutch disengagement, a clutch pressure increase above or decrease below the target range, an oil temperature exceeding a threshold, or a detected fault condition. For example, an indication that the clutch disengagement before cycling exceeds a second threshold duration (e.g., 0.2 seconds) may cause the state machine 200 to transition from the active closed-loop cleaning mode 202 to the idle mode 201.

[0031] The clutch cleaning system can be considered to be operating in the completed closed cleaning mode 204 when the clutch cleaning system has completed the closed cleaning process. The clutch cleaning system can transition from the completed closed cleaning mode 204 to the idle mode 201, represented by arrow 224. For example, the clutch cleaning system can transition from the completed closed cleaning mode 204 to the idle mode 201 when the closed cleaning process reaches a closed cleaning time threshold or a calibrated percentage of the closed cleaning time threshold has elapsed and a cleaning abort request is triggered.

[0032] Fig. 3 shows a flowchart for a method 300. The method 300 is an example of the disclosed methods for cleaning a closed clutch. In particular, the method 300 may be an approach for cleaning a clutch valve that controls the clutch mechanisms in a dual-clutch transmission, such as the dual-clutch assembly 118 described above with reference to Fig. 1. The instructions for performing the method 300 may be executed by a controller based on commands stored in a memory of the controller and in conjunction with signals received from sensors of the vehicle system, such as the controller 191, the memory 193 and the sensors 194 described above with reference to Fig. 1. The controller may use actuators of the vehicle system to adjust vehicle operation, such as the clutch actuator system 154 and the actuators 195 described above with reference to Fig. 1, according to the procedures described below.

[0033] At 302, method 300 includes estimating and / or measuring the operating conditions. The operating conditions may include, for example, the engagement status of one or more clutches (e.g., the first clutch mechanism 143, the second clutch mechanism 144 in Fig. 1) and may additionally or alternatively include a duration of engagement / disengagement of the one or more clutches. The operating conditions may include one or more of a clutch pressure request, a clutch torque request, an engine torque request, oil temperature, oil pressure, hydraulic line pressure, and / or fault conditions of one or more transmission components, such as clutch valves, sensor(s), and others.

[0034] At 304, method 300 includes determining whether a clutch is closed (engaged) and in lock-up torque control for a threshold duration. In one example, the threshold duration may be a positive non-zero threshold, such as 0.5 seconds. In response to determining that the clutch is not closed for longer than the threshold duration, method 300 may maintain default operation at 308. For example, method 300 may maintain default operation if it is determined that the clutch is open or if it is determined that the clutch is in lock-up torque control for a duration less than or equal to the threshold duration.

[0035] In response to determining that the clutch is in lock-up torque control for longer than the threshold duration, method 300 may include determining at 306 whether the clutch pressure request is within a threshold range. In one example, the threshold range may include a lower threshold and an upper threshold, each of which may be positive, non-zero thresholds. In one example, the threshold range is a fixed range that is calibrated for different applications. In one example, the threshold range may be 4-16 bar. In response to determining that the clutch pressure is not within the threshold range, method 300 may maintain default operation at 308.For example, before performing the clutch closed cleaning event, method 300 determines the conditions for the duration of the lock-up torque control and whether the clutch pressure is within a threshold range. For example, in a situation where the clutch is closed and the pressure is not within the threshold range, the method may include maintaining standard operation at 308 and returning to the beginning of method 300. In this way, the system can continue to monitor the conditions that trigger a clutch closed cleaning event.

[0036] In response to determining that the clutch pressure request is within the threshold range, method 300 may include performing the clutch closed cleaning operation at 310. The clutch closed cleaning operation may include sending a valve cleaning control pulse to an actuator of the clutch valve at 312. The clutch closed cleaning operation may further include setting a timer for the cleaning operation at 314. The clutch closed cleaning operation may also include monitoring for abort conditions at 316.

[0037] For example, the valve cleaning control pulse sent at 312 may be the same as or similar to the valve cleaning control pulse described with reference to Fig. 2-3. The controller may determine a control signal to be sent to the clutch valve, e.g., a pulse width of the signal determined based on a first clutch pressure threshold and a second clutch pressure threshold. For example, the first clutch pressure threshold may be a positive non-zero pressure threshold calibrated to maintain the clutch pressure above the nominal pressure for the engine torque request. The second clutch pressure threshold may be a positive non-zero pressure threshold calibrated to maintain an adequate line pressure in the hydraulic system. In one example, the valve cleaning control pulse moves the valve spool up and down at a high speed, creating a jiggling effect that may dislodge contaminants and increase the flow rate through the valve spool.The timer for the cleaning operation at 314 may be set to a first threshold duration. In one example, the first threshold duration is a dynamic value based on an expected fouling of the valve based on operation, previous cleaning, and previous cleaning duration. Alternatively, the first threshold duration may be based on a fixed value empirically determined to fully clean the valve. In one example, a clean valve is a valve with a soot / dirt load below a threshold (e.g., 5% or less), and a fouled valve is a valve with a soot / dirt load greater than or equal to the threshold. For example, when the valve is cleaned, it is placed in a less-fouled state.In one example, the controller may determine a control signal to be sent to a countdown timer of the vehicle system, determined based on the first threshold duration. The first threshold duration may be, for example, 0.5 seconds. During the valve cleaning control pulse, abort conditions may be monitored at 316, including, but not limited to, one or more of the following conditions: expected clutch disengagement, clutch pressure request outside the threshold range, oil temperature above a threshold, hydraulic line pressure above a threshold, fault detection. In one example, the abort conditions may be early abort conditions that result in the clutch cleaning process being aborted before the first threshold duration, while the first threshold duration results in the clutch cleaning process being aborted due to method completion.

[0038] At 316, method 300 may include determining whether the clutch cleaning operation is performed for longer than the first threshold duration. In response to determining that the clutch cleaning operation is performed for longer than the first threshold duration, method 300 may include terminating the clutch-closed cleaning operation at 320. In response to determining that the cleaning operation has not been performed for longer than the first threshold duration, method 300 may include determining whether at least one termination condition is met at 325. In response to determining that at least one termination condition is not met, method 300 may return to 318.

[0039] At 320, ending (or pausing) the clutch closed cleaning operation may include adjusting the clutch pressure request to the clutch pressure calibrated to maintain the engine torque request. For example, the controller may determine a control signal to send to the clutch valve, such as a pulse width of the signal, determined based on the engine torque request.

[0040] At 322, method 300 may include setting a delay timer. In one example, the delay timer may be set to introduce a delay before initiating a clutch-closed cleaning event (e.g., another clutch-closed cleaning event). For example, the delay timer may prevent execution of a clutch-closed cleaning event until a threshold time interval has elapsed. In one example, the controller may determine a control signal to a delay timer of the vehicle system determined based on the threshold time interval. In one example, the threshold time interval may be a positive, non-zero threshold duration. In one example, the threshold time interval may be calibrated based on one or more conditions of the hydraulic system, the clutch, the clutch valve, and / or other parameters.In one example, the threshold time interval may be 600 seconds.

[0041] At 324, method 300 may include determining whether the delay has exceeded the threshold time interval. In response to determining that the delay timer has exceeded the threshold time interval, method 300 may return.

[0042] Returning to 325, in response to determining that at least one termination condition is met, method 300 may include determining whether the clutch closed cleaning operation has been performed for more than a second threshold duration at 326. In one example, the second threshold duration may be a positive non-zero threshold duration that may be shorter than the first threshold duration but sufficient to loosen contaminants in the clutch valve. For example, the second threshold duration may be 30% of the first threshold duration or 0.2 seconds. In response to determining that the cleaning operation is not performed for more than the second threshold duration, method 300 may include ending the cleaning operation at 328 and returning.By returning in response to the premature termination of the cleaning process without sufficient duration, the cleaning process can be initiated without delay with the clutch closed in response to the detection of the above-mentioned operating conditions.

[0043] In response to determining that the clutch closed cleaning operation is performed for longer than the second threshold duration, method 300 may include terminating the clutch closed cleaning operation at 330. As above, in one example, terminating the clutch closed cleaning operation may include adjusting the clutch pressure request to the rated clutch pressure for the engine torque request.

[0044] At 332, method 300 may include setting the delay timer.

[0045] At 334, method 300 may include determining whether the delay timer has exceeded the threshold time interval. In one example, the threshold time interval may be the same as or similar to the threshold time interval described above, e.g., 600 seconds. In response to determining that the delay timer has exceeded the threshold time interval, method 300 may return.

[0046] Fig. 4 illustrates timing diagrams 400, 420, 430, 440 showing a sequence of actions performed as part of a method for cleaning a clutch valve of a closed clutch for an exemplary vehicle system. In particular, the method may be an approach for cleaning a clutch valve that controls the clutch mechanisms in a dual-clutch transmission, such as the first clutch mechanism 143 and the second clutch mechanism 144 of the dual-clutch assembly 118 described above with reference to the vehicle 100 of Fig. 1. The method for cleaning a clutch valve may include the same or a similar series of actions as described above with reference to method 300 in Fig. 3. The instructions for performing the method described in the timing diagrams 400, 420, 430, 440 may be executed by a controller (e.g., controller 191) based on instructions stored in a memory of the controller and in conjunction with sensory feedback received from components of the vehicle's transmission system (e.g., sensors 194), as described above with reference to Fig. 1. In the prophetic examples, the controller determines whether entry conditions are indicated. If the entry conditions are indicated, a clutch valve cleaning control pulse may be generated to perform a clutch closed cleaning operation. The pressure demand and sensor feedback are monitored throughout the cleaning operation. If one or more abort conditions are indicated, the controller aborts the cleaning operation. Timing diagram 400 illustrates a scenario in which the cleaning operation is performed for the first threshold duration. Timing diagram 420 illustrates a scenario in which the cleaning operation is aborted in response to detecting a first abort condition. Timing diagram 430 illustrates a scenario in which the cleaning operation is aborted in response to detecting a second abort condition.Timing diagram 440 shows a scenario in which the cleaning process is executed for the second threshold duration. The horizontal (x-axis) denotes time, and the vertical markers t0-t3 indicate the relevant times in timing diagrams 400, 420, 430, and 440 for cleaning a closed clutch. The dotted shading represents the time periods in timing diagrams 400, 420, 430, and 440 in which the entry conditions for executing the cleaning process with the clutch closed are specified.

[0047] The timing diagram 400 shows waveforms 402, 404, 406, 408, 410, which represent the states of the components and / or the control settings of the vehicle system over time. Waveform 402 indicates a clutch valve pressure request. Generating a valve purge request may rapidly increase and decrease the clutch valve pressure request between a first clutch pressure threshold and a second clutch pressure threshold, which appears as a sawtooth pattern in the valve pressure request signal. In other words, the pressure zigzags between the first and second clutch pressure thresholds. Waveform 404 shows a nominal clutch pressure threshold, which may be a clutch pressure calibrated to maintain a torque demanded by the engine. Waveforms 406 and 408 show minimum and maximum clutch pressure thresholds, respectively.a maximum vertical clutch pressure, which may represent a low pressure threshold range during the cleaning request with the clutch valve closed. For example, during the valve cleaning request, the first clutch pressure threshold may be set to the maximum vertical clutch pressure. The valve cleaning request may be aborted early if the system determines that the clutch valve pressure request is below the minimum vertical pressure. Waveform 410 shows an upper pressure threshold, which may be the second clutch pressure threshold of the valve cleaning request. For example, a sensor signal indicating that the clutch valve pressure request exceeds the second clutch pressure threshold may cause the valve cleaning request to be aborted early.

[0048] At t0, the diagram 404 shows the nominal clutch pressure, e.g., 12 bar, to engage the clutch (e.g., the first clutch mechanism 143 in Fig. 1) in the closed position at the current engine torque demand. The clutch valve pressure demand, as shown by curve 402, is substantially comparable to the nominal clutch pressure threshold. Curve 410 indicates the upper pressure threshold, e.g., 20 bar, detected by one of the sensors 194 in the hydraulic system 150.

[0049] From t0 to t1 the clutch remains engaged, as can be seen from curve 402, which overlaps with curve 404.

[0050] At time t1, the conditions for performing the cleaning process with the clutch closed are met. For example, the clutch is engaged and in lockup torque control for longer than a threshold duration, e.g., from t0 to t1, and the clutch valve pressure demand is within a target range, e.g., between 4 bar and 16 bar.

[0051] From t1 to t2, the system performs the clutch-closed cleaning process. The clutch valve pressure demand, as shown in trace 402, cyclically increases to the second pressure threshold, as shown in trace 410, and then decreases to the first pressure threshold, as shown in trace 408, which appears as the sawtooth pattern mentioned above. During the clutch-closed cleaning process, the system monitors for abort conditions. For example, the abort conditions may include monitoring the clutch valve pressure demand, as shown in trace 402, and whether the clutch valve pressure demand is outside the target range, e.g., greater than the second threshold, as shown in trace 410, or less than the first threshold, as shown in trace 406.

[0052] At t2, the clutch-closed cleaning cycle exceeds a first threshold duration, e.g., from t1 to t2. In one example, t1 to t2 may be 0.4 seconds. Therefore, at t2, the clutch-closed cleaning cycle is terminated, and the clutch valve pressure demand is set to the nominal clutch pressure to maintain the clutch closed at the current engine torque demand.

[0053] The timing diagram 420 shows the waveforms 422, 424, 426, 428, 429, which represent the states of the components and / or the control settings of the vehicle system over time. Waveform 422 indicates the pressure demand of the clutch valve. Waveform 424 shows the nominal threshold for the clutch pressure. Waveforms 426 and 428 show the minimum and maximum vertical clutch pressure, respectively. Waveform 429 shows the upper pressure threshold. In the example, the waveforms 422, 424, 426, 428, 429 can be determined in a similar manner as described with respect to the timing diagram 400. In addition, the curves 422, 424, 426, 428, 429 can control the execution of the cleaning process with the clutch closed in a similar manner as described with respect to the timing diagram 400.Timing diagram 420 also includes an abort condition threshold, represented by waveform 425, and an abort condition sensor, represented by waveform 427. During a clutch-closed cleaning operation, the system may receive signals from the abort condition sensor, and in response to the sensor signal indicating an abort condition that exceeds the abort condition threshold, the system may terminate the clutch-closed cleaning operation. In this example, the abort condition threshold may be an oil temperature threshold, and the abort condition sensor may be an oil temperature sensor.

[0054] At t0, curve 424 indicates the nominal clutch pressure, e.g., 12 bar, required to maintain the clutch in the closed position at the current engine torque demand. The clutch valve pressure demand, as shown by curve 422, is essentially comparable to the nominal clutch pressure threshold. Curve 429 indicates the upper pressure threshold, e.g., 20 bar, detected by one of the sensors 194 in the hydraulic system.

[0055] From t0 to t1 the clutch remains engaged, as can be seen from curve 422, which overlaps with curve 424.

[0056] At time t1, the conditions for performing the cleaning process with the clutch closed are met. For example, the clutch is engaged and in lockup torque control for longer than a threshold duration, e.g., from t0 to t1, and the clutch valve pressure demand is within the target range, e.g., between 4 bar and 16 bar.

[0057] From t1 to t2, the system performs the clutch-closed cleaning cycle. The clutch valve pressure demand, as shown by trace 422, cyclically increases to the second pressure threshold, as shown by trace 429, and then decreases to the first pressure threshold, as shown by trace 428. During the clutch-closed cleaning cycle, the system monitors for abort conditions, including receipt of signals from the oil temperature sensor, as shown by trace 427. As time t2 approaches, the oil temperature sensor indicates an oil temperature approaching the oil temperature threshold, as shown by trace 425.

[0058] At t2, the system detects at least one abort condition. In this example, the oil temperature sensor indicates that the oil temperature has exceeded the oil temperature threshold. Therefore, at t2, the clutch closed cleaning process is aborted and the clutch valve pressure demand is set to the rated clutch pressure to maintain the clutch closed at the current engine torque demand. In the example, t1 to t2 is shorter than a second threshold duration represented by t1 to t3, therefore the clutch cleaning process may be initiated in response to the entry conditions being met without a delay interval. In one example, t1 to t3 may equal 0.2 seconds.

[0059] The timing diagram 430 shows the waveforms 432, 434, 436, 438, 439, which represent the states of the components and / or the control settings of the vehicle system over time. Waveform 432 indicates the pressure demand of the clutch valve. Waveform 434 shows the nominal threshold for the clutch pressure. Waveforms 436 and 438 show the minimum and maximum vertical clutch pressure, respectively. Waveform 439 shows the upper pressure threshold. In the example, waveforms 432, 434, 436, 438, 439 can be determined in a similar manner as described with respect to the timing diagram 400. In addition, the curves 432, 434, 436, 438, 439 can control the execution of the cleaning process with the clutch closed in a similar manner as described with respect to the timing diagram 400.

[0060] At t0, curve 434 indicates the nominal clutch pressure, e.g., 12 bar, required to maintain the clutch in the closed position at the current engine torque demand. The clutch valve pressure demand, as shown by curve 432, is essentially comparable to the nominal clutch pressure threshold. Curve 439 indicates the upper pressure threshold, e.g., 20 bar, detected by one of the sensors 194 in the hydraulic system.

[0061] From t0 to t1 the clutch remains engaged, as can be seen from curve 432, which overlaps with curve 434.

[0062] At time t1, the conditions for performing the cleaning process with the clutch closed are met. For example, the clutch is engaged and in lockup torque control for longer than a threshold duration, e.g., from t0 to t1, and the clutch valve pressure demand is within the target range, e.g., between 4 bar and 16 bar.

[0063] From time t1 to t2, the system performs the cleaning process with the clutch closed. As previously shown, the clutch valve pressure demand oscillates between the first pressure threshold and the second pressure threshold, shown in curves 438 and 439, respectively, while the system monitors the abort conditions. As time t2 approaches, one of the sensors 194 indicates an increasing nominal clutch pressure demand (see curve 434).

[0064] At t2, the system detects at least one abort condition. In this example, the increasing nominal clutch pressure demand causes the clutch closed cleaning process to abort. Therefore, at t2, the clutch valve pressure demand is set to the nominal clutch pressure (434) to maintain the clutch closed at the current engine torque demand. In the example, t1 to t2 is shorter than the second threshold duration represented by t1 to t3, therefore the clutch cleaning process may be initiated in response to the entry conditions being met without a delay interval. In one example, t1 to t3 may equal 0.2 seconds.

[0065] The timing diagram 440 shows the waveforms 442, 444, 446, 448, 449, which represent the states of the components and / or the control settings of the vehicle system over time. Waveform 442 indicates the pressure demand of the clutch valve. Waveform 444 shows the nominal threshold for the clutch pressure. Waveforms 446 and 448 show the minimum and maximum vertical clutch pressure, respectively. Waveform 449 shows the upper pressure threshold. In the example, the waveforms 442, 444, 446, 448, 449 can be determined in a similar manner as described with respect to the timing diagram 400. In addition, the curves 442, 444, 446, 448, 449 can control the execution of the cleaning process with the clutch closed in a similar manner as described with respect to the timing diagram 400.The timing diagram 440 also includes an abort condition threshold, illustrated in waveform 445, and an abort condition sensor, illustrated in waveform 447, which may be the oil temperature threshold or oil temperature sensor described with respect to the timing diagram 420.

[0066] At t0, curve 444 indicates the nominal clutch pressure, e.g., 12 bar, required to maintain the clutch in the closed position at the current engine torque demand. The clutch valve pressure demand, as shown by curve 422, is essentially comparable to the nominal clutch pressure threshold. Curve 449 indicates the upper pressure threshold, e.g., 20 bar, detected by one of the sensors 194 in the hydraulic system.

[0067] From t0 to t1 the clutch remains engaged, as can be seen from curve 442, which overlaps with curve 444.

[0068] At time t1, the conditions for performing the cleaning process with the clutch closed are met. For example, the clutch is engaged and in lockup torque control for longer than a threshold duration, e.g., from t0 to t1, and the clutch valve pressure demand is within the target range, e.g., between 4 bar and 16 bar.

[0069] From t1 to t2, the system performs the clutch-closed cleaning cycle. The clutch valve pressure demand, as shown by trace 422, cyclically increases to the second pressure threshold, as shown by trace 449, and then decreases to the first pressure threshold, as shown by trace 448. During the clutch-closed cleaning cycle, the system monitors for abort conditions, including receipt of signals from the oil temperature sensor, as shown by trace 447. As time t2 approaches, the oil temperature sensor indicates an oil temperature approaching the oil temperature threshold, as shown by trace 445.

[0070] At t2, the system detects at least one abort condition. In this example, the oil temperature sensor indicates that the oil temperature has exceeded the oil temperature threshold. Therefore, at t2, the clutch-closed cleaning process is aborted and the clutch valve pressure demand is set to the rated clutch pressure to maintain the clutch in the closed position at the current engine torque demand. In this example, t1 to t2 is greater than a second threshold duration. The second threshold duration can be shorter than the first threshold duration but sufficient to dislodge contaminants in the clutch valve, for example, 0.2 seconds. Therefore, a delay timer is set with an interval of t2 to t3.

[0071] From t2 to t3, a countdown timer that measures the delay time prevents the system from initiating a cleaning process when the clutch is closed.

[0072] At t3, the deceleration interval ends and the system monitors the entry conditions to initiate the clutch closed cleaning process.

[0073] In this way, a clutch valve is automatically cleaned when the clutch is closed. By initiating a clutch valve cleaning operation when the clutch is in lock-up torque control, the clutch valve is cleaned during steady-state driving, including conditions where valve movement is reduced and / or hydraulic flow through the valve is reduced—conditions most likely to cause contaminants to build up in the clutch valve. The technical effect of the disclosed systems and methods is to increase the frequency of clutch valve cleaning, which may reduce the accumulation of contaminants that could otherwise lead to clutch degradation and / or reduced performance.

[0074] The disclosure also provides support for a method comprising sending a valve cleaning control pulse to a valve in response to a clutch remaining in an engaged position and a clutch pressure request being within a threshold pressure range, and interrupting the valve cleaning control pulse in response to detecting at least one abort condition. In a first example of the method, the at least one abort condition includes an expected clutch disengagement and / or a clutch pressure request outside the threshold pressure range. In a second example of the method, optionally including the first example, the at least one abort condition includes an oil temperature exceeding an upper threshold or falling below a lower threshold.In a third example of the method, optionally including one or both of the first and second examples, the at least one termination condition comprises determining a component failure. In a fourth example of the method, optionally including one or more or each of the first to third examples, maintaining the clutch in the engaged position comprises a clutch torque request above a current engine torque. In a fifth example of the method, optionally including one or more or each of the first to fourth examples, the clutch comprises one of a first clutch mechanism and a second clutch mechanism of a dual clutch transmission. In a sixth example of the method, optionally including one or more or each of the first to fifth examples, the valve is a spool valve.In a seventh example of the method, optionally including one or more or each of the first to sixth examples, the valve cleaning control pulse comprises cyclically setting a valve pressure between a first threshold and a second threshold for a second threshold duration. In an eighth example of the method, optionally including one or more or each of the first to seventh examples, the method further comprises: interrupting the valve cleaning control pulse in response to the valve cleaning control pulse exceeding the second threshold duration; and setting a delay timer. In a ninth example of the method, optionally including one or more or each of the first to eighth examples, the delay timer is set for 600 seconds.

[0075] The disclosure also provides support for a system comprising: a transmission configured to rotatably couple a prime mover to a drive shaft, a first input shaft coupled to the transmission, a second input shaft coupled to the transmission, a dual clutch assembly comprising a first clutch mechanism and a second clutch mechanism, the first clutch mechanism and the second clutch mechanism selectively coupling either the first input shaft or the second input shaft to the prime mover in response to a clutch pressure request, a valve configured to control a flow of hydraulic fluid to the dual clutch assembly, and a controller including non-transitory commands,stored in a memory and operable to: send a valve cleaning control pulse to the valve in response to determining that one of the first clutch mechanism and the second clutch mechanism remains in an engaged position for a first threshold duration and the clutch pressure request is within a threshold pressure range, and interrupt the valve cleaning control pulse in response to determining at least one abort condition. In a first example of the system, the valve is a spool valve. In a second example of the system, optionally including the first example, the first input shaft is an inner shaft and the second input shaft is an outer input shaft coaxial with the first input shaft. In a third example of the system, optionally including one or both of the first and second examples,The at least one termination condition includes an expected clutch disengagement and / or a clutch pressure request outside the threshold pressure range. In a fourth example of the system, optionally including one or more or each of the first through third examples, the valve cleaning control pulse includes cyclically adjusting a valve pressure between a first threshold and a second threshold for a second threshold duration.

[0076] The disclosure also provides support for a method comprising: executing a clutch-closed cleaning event in response to clutch engagement in lock-up torque control exceeding a first threshold duration and a clutch pressure request being within a threshold pressure range, wherein a valve cleaning control pulse is sent to a valve; interrupting the clutch-closed cleaning event in response to detecting at least one abort condition; and setting a delay timer in response to the valve cleaning control pulse exceeding a second threshold duration. In a first example of the method, the at least one abort condition includes an expected clutch disengagement and / or a clutch pressure request outside the threshold pressure range.In a second example of the method, optionally including the first example, the at least one termination condition comprises an oil temperature exceeding an upper threshold or falling below a lower threshold. In a third example of the method, optionally including one or both of the first and second examples, the at least one termination condition comprises determining a component fault. In a fourth example of the method, optionally including one or more or each of the first through third examples, the clutch intervention in the lock-up torque control comprises a clutch torque request above a current engine torque.

[0077] In another representation, a method includes selecting a closed clutch cleaning event from a plurality of cleaning events in response to operating conditions indicating that a clutch engagement in the lock-up torque control exceeds a threshold duration and a clutch pressure is within a threshold pressure range, performing the closed clutch cleaning event while monitoring one or more abort conditions in response to selecting the clutch cleaning event, and aborting the clutch cleaning event in response to the operating conditions indicating at least one of the one or more abort conditions.

[0078] It should be noted that the example control and estimation routines contained herein can be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in non-volatile memory and executed by the control system, including the controller, in combination with the various sensors, drive elements, and other engine hardware. The specific routines described herein can represent one or more of any processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. Thus, the various actions, operations, and / or functions illustrated can be performed in the order illustrated, in parallel, or, in some cases, without them.Accordingly, the order of processing is not required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for convenience of illustration and description only. One or more of the illustrated actions, operations, and / or functions may be performed repeatedly depending on the strategy used. Furthermore, the described actions, operations, and / or functions may graphically represent code to be programmed into the non-volatile memory of the computer-readable storage medium in the engine control system, wherein the described actions are carried out by executing the instructions in a system including the various hardware components of the engine in combination with the electronic controller.

[0079] It should be understood that the configurations and routines disclosed herein are exemplary in nature and that these specific embodiments should not be considered limiting, as numerous variations are possible. For example, the technology described above may be applied to V-6, I-4, I-6, V-12, horizontally opposed engines, and other engine types. Unless expressly stated otherwise, the terms "first," "second," "third," etc., are not intended to denote any order, position, quantity, or importance, but are used merely to distinguish the individual elements. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, as well as other features, functions, and / or characteristics disclosed herein.

[0080] The term “substantially” means, unless otherwise specified, plus or minus five percent of the range.

[0081] The following claims particularly point out certain combinations and subcombinations that are considered novel and non-obvious. These claims may refer to "a" element or "a first" element, or the equivalent thereof. Such claims are to be construed as including the inclusion of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by filing new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope than the original claims, are also to be considered included within the subject matter of the present disclosure.

Claims

[1] System that includes: a transmission configured to rotatably couple a prime mover to a drive shaft; a first input shaft coupled to the transmission; a second input shaft coupled to the transmission; a dual clutch assembly comprising a first clutch mechanism and a second clutch mechanism, the first clutch mechanism and the second clutch mechanism selectively coupling the first input shaft or the second input shaft to the prime mover in response to a clutch pressure request; a valve configured to control a flow of hydraulic fluid to the dual clutch assembly; and a controller containing non-volatile instructions stored in memory that are executable to: Sending a valve cleaning control pulse to the valve in response to determining that the first clutch mechanism or the second clutch mechanism remains in an engaged position for a first threshold duration and the clutch pressure request is within a threshold pressure range; and Interrupting the valve cleaning control pulse in response to the detection of at least one abort condition. [2] The system of claim 1, wherein the valve is a gate valve. [3] A system according to any preceding claim, wherein the first input shaft is an inner shaft and the second input shaft is an outer input shaft coaxial with the first input shaft. [4] A system according to any one of the preceding claims, wherein the at least one abort condition comprises an expected clutch disengagement and / or a clutch pressure request outside the threshold pressure range. [5] A system according to any preceding claim, wherein the valve cleaning control pulse comprises cyclically adjusting a valve pressure between a first threshold value and a second threshold value for a second threshold duration. [6] The system of claim 5, further comprising interrupting the valve cleaning control pulse in response to the valve cleaning control pulse exceeding the second threshold duration; and setting a delay timer. [7] System according to one of the preceding claims, wherein the at least one termination condition comprises detecting a component failure.

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