DE102013114958A1 - Vehicle has transmission control module (TCM) that is adapted to compute difference between computed clutch torque and ordered clutch torque, and control position of input clutch using computed difference to provide feedback term - Google Patents

Abstract

The vehicle (10) has a TCM (20) to receive a starting request of vehicle, receive actual torque value of combustion engine (12) from an engine control module (ECM) (30), determine inertia torque value and inertia of engine, compute the clutch torques of the input clutches (C1,C2) of a dual clutch transmission (DCT) component (14) with respect to actual torque value of engine and moment of inertia value, compute a difference between the computed clutch torque (TCALC) and the ordered clutch torque, and controls a position of clutch using computed difference to provide a feedback term.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61 / 749,592, filed January 7, 2013, which is incorporated herein by reference in its entirety.

TECHNICAL AREA

This disclosure relates to the starting control of a vehicle having a dual-clutch transmission.

BACKGROUND

Dual-clutch transmissions combine certain features of manual and automatic transmissions. In a dual clutch or DCT with odd and even gear sets, one of a pair of input clutches is engaged to engage any of the odd gear sets. Likewise, the other input clutch is engaged to engage any of the even gear sets. An on-board controller predicts the next gear to be selected using available control inputs, such as engine acceleration and brake levels, and then commands engagement of the next gear at the beginning of the upcoming shift. Compared to a conventional transmission, a DCT can provide faster gear changes, usually with improved shift control and increased power.

The two available input clutches in a wet DCT are cooled and lubricated by transmission fluid, which is circulated via an engine-driven or auxiliary fluid pump. In a dry DCT (dDCT), the various gear sets inside a gear box of the DCT are cooled and lubricated in the same manner while the two input clutches remain dry. As a result, a dDCT may experience a greater amount of temperature-related power fluctuation relative to a wet DCT.

SUMMARY

Disclosed herein is a vehicle having a dual clutch transmission (dDCT) and a transmission control module (TCM). The TCM serves to execute a startup control method of the present invention. The method can be used in the start-up control of any DCT, whether dry or wet, as described above. In the example embodiments disclosed herein, an engine control module (ECM) and the TCM cooperate during vehicle launch to eventually calculate and modify, over time, a position control signal used to control a position of a particular one of the input clutches of the DCT. The position signal ultimately commands an engagement position of the particular input clutch, i. H. an axial position of the piston or other actuator (s) used to engage the input clutch. An objective of the present approach is to achieve a start of the vehicle with a smooth, consistent behavior.

In a particular embodiment, the vehicle includes an engine and a DCT assembly. The DCT assembly includes the TCM and first and second input clutches. The first and second input clutches connect the prime mover to respective first and second gear sets of the DCT. The vehicle also includes the ECM as mentioned above. The ECM otherwise extracts, calculates or provides an actual engine torque value. The TCM, which communicates with the input clutches and the ECM, each time receives a start request from the ECM when a driver of the vehicle depresses an accelerator pedal by a sufficiently large range or percentage of the adjustment path.

In response to the received start request, the TCM next derives a calculated clutch torque (T _CALC ) as a function of the engine torque (T _E ) and an inertia torque value, the latter of which is the product of the acceleration (α) and known inertia (I) of the engine is determined. The TCM then compares the calculated clutch torque value with a commanded clutch torque, e. A signal from the TCM. Any deviation between the engine torque and the calculated torque is used to perform closed-loop control of the clutch position to cause the engine torque and the calculated torque to merge. The TCM may modify a recorded torque-to-position (TTP) table in memory such that when the calculated clutch torque exceeds the commanded clutch torque, less clutch torque in the TTP table corresponds to a given engagement position of the particular input clutch, and so more clutch torque in the TTP table corresponds to the given engagement position every time the calculated clutch torque is less than the commanded one Clutch torque is. The TCM then transmits a clutch position signal to the particular input clutch to thereby command an engagement position of the input clutch extracted from the recorded TTP table.

It is also a DCT system for a vehicle with an engine and an ECM disclosed. The DCT system includes first and second input clutches, first and second gear sets, and a TCM. The first gear set is selectively connected to the engine via the first input clutch. Likewise, the second gear set is selectively connected to the engine via the second input clutch. The TCM in communication with the ECM receives a startup request, and in response receives an actual torque of the engine and determines acceleration and inertia values of the engine. The TCM then derives the calculated clutch torque by subtracting the product of the acceleration and inertia values from the actual torque of the engine and comparing the calculated clutch torque to the commanded clutch torque. As mentioned above, the TTP table is adjusted based on this difference, and the TCM transmits a clutch position signal to the particular input clutch to command an engagement position of the input clutch, extracting the position from the recorded TTP table.

There is also disclosed an associated start-up control method for the vehicle described above. The method includes receiving a start request via the TCM, receiving an actual torque of the engine from the ECM, determining the acceleration and inertia of the engine, and then calculating a clutch torque for a particular input clutch from the first and second input clutches as one Function of the actual torque of the engine and the acceleration and inertia values. The method also includes comparing the calculated clutch torque with the commanded clutch torque, and transmitting a corresponding control position signal to the particular input clutch to thereby increase or decrease a clutch engagement position of the particular input clutch depending on the results of that comparison.

The above features and advantages and other features and advantages of the present invention will become more readily apparent from the following detailed description of some of the best modes and other embodiments for carrying out the invention as defined in the appended claims, taken in conjunction with the accompanying drawings become clear.

BRIEF DESCRIPTION OF THE DRAWINGS

1 FIG. 12 is a schematic illustration of a vehicle having a dual clutch transmission (DCT) with a clutch position controlled during vehicle launch using a launch control method as described herein. FIG.

2 is a set of timing diagrams describing the changing amplitudes of various vehicle performance values, time plotted on the horizontal axis and amplitude plotted on the vertical axis.

3 FIG. 15 is a timing chart of an example clutch position control signal for an input clutch of the in 1 shown DCT, the time is plotted on the horizontal axis and the amplitude is plotted on the vertical axis.

4 is an example torque-to-position model associated with the vehicle of 1 is usable, wherein the commanded clutch torque is plotted on the horizontal axis and the clutch position is plotted on the vertical axis.

5 FIG. 10 is a flowchart illustrating an example embodiment of a vehicle startup control method for the in 1 described vehicle or for any other vehicle having a wet or a dry DCT as part of its drive train describes.

DETAILED DESCRIPTION

With reference to the drawings, wherein like reference numbers refer to like components throughout the several figures, in FIG 1 a vehicle 10 shown schematically. The vehicle 10 includes an internal combustion engine 12 and a dual clutch transmission (DCT) assembly 14 , with the engine (E) 12 , The speed of the engine 12 responds to a received gas request (arrow Th%), z. As a force or a percentage of movement of an accelerator pedal 11 or other suitable device that indicates a relative level of requested torque of the engine. Such a force / path may be detected via a sensor (not shown) in a conventional manner. In response to receiving the gas request (arrow Th%), the engine generates 12 Input torque (arrow T _I ) in the DCT module 14 and supplies the input torque (arrow T _I ) to the DCT board 14 via a rotatable drive element 15 ,

As understood in the art, a DCT is an automated manual transmission that includes a gearbox 13 with two independently actuated input clutches, ie, the respective in 1 shown first and second input clutch C1 and C2 ,. Although for the sake of simplicity of illustration 1 omitted, each input clutch C1 and C2 may include a center plate containing any number of friction plates, friction plates or other suitable friction materials. The input couplings C1 and C2 of the DCT module 14 may be lubricated / wet, or they may be dry, with both constructions described above. That is, fluid (arrow F) may be through an engine driven fluid pump 31 to the input clutches C1, C2 in a wet DCT embodiment, or the fluid (arrow F) in a dry DCT embodiment can only to the gear box 13 be circulated. Associated electronic and hydraulic clutch control devices (not shown) ultimately control the shifting operation and starting of the vehicle in response to instructions from various on-board controllers, as explained in detail below.

In the example DCT board 14 from 1 the first input clutch C1 controls all the odd gear sets 24 (GS _O ) of the DCT board 14 for example, the first, third, fifth and seventh gears in an example 7-speed transmission, while the second input clutch C2 each even-numbered gear set 124 (GS _E ) controls, for example, the second, fourth and sixth in the same example 7-speed transmission. Inside each of the gear sets 24 . 124 can additional couplings, z. As hydraulic, piston-operated, rotating or braking clutches are engaged or disengaged as required to produce the desired gear state. The reverse gear state can be part of the odd gear set 24 be controlled via the first input clutch C1. Using this type of gear arrangement, the DCT assembly can 14 be quickly switched through their available range of gears, without the power flow from the engine 12 completely interrupt.

The controllers of in 1 shown vehicle 10 include at least one transmission control module (TCM) 20 and an engine control module (ECM) 30 , As follows with reference to the 2 - 4 executed, works the TCM 20 in conjunction with the ECM 30 during startup of the vehicle 10 to thereby an engine acceleration-based, position control arbitrary actuators of the particular input clutch, z. B. clutch piston set. In general, the input clutch C1 would be used for starting in 1st gear, although starting operations in other gears is not excluded, and thus input clutch C2 could be controlled in the same way. For a dry DCT, the present approach control approach can help to focus on the fundamental variations to improve start-up quality. Although such variation is typically more prevalent in a dry DCT due to the lack of cooling at the friction interfaces of the input couplings, starting a vehicle with a wet DCT may also benefit from the present invention.

In the example vehicle 10 from 1 includes the DCT board 14 also an output shaft 21 which is connected to a set of drive wheels (not shown). The output shaft 21 Finally, transmits output torque (arrow T _O ) to the drive wheels to the vehicle 10 drive. The DCT board 14 can be a first wave 25 connected to the first input clutch C1, a second shaft 27 , which is connected to the second input clutch C2, and respective even and odd gear sets 24 . 124 (GS _O , GS _E ) included within the gearbox 13 is arranged, both via circulation of a transmission fluid from a sump 35 via an engine-driven main pump 31 , z. B. via a pump shaft 37 , or alternatively via an auxiliary pump (not shown) can be cooled and lubricated.

Inside the DCT board 14 is the first wave 25 with only the odd gear sets 24 (GS _O ) connected and drives these. The second wave 27 is with only the straight gear sets 124 (GSE), which include a reverse gear set, connected and powered. The DCT board 14 further includes upper and lower main shafts 17 respectively. 19 fitted with final drive (F / D) gear sets 34 . 134 are connected. The final drive gear sets 34 and 134 are in turn with the output shaft 21 the DCT board 14 connected and are designed to provide any required Achsgetriebeuntersetzung.

With reference to the controller of the vehicle 10 can the TCM 20 and the ECM 30 be designed as microprocessor-based devices having components, such as processors 22 . 32 , Storage 23 . 33 including tangible, non-transitory computer-readable media such as read-only memory (ROM), optical memory, solid state flash memory, and the like, and random access memory (RAM), electrically erasable programmable read only memory (EEPROM). Flash memory, etc. includes, but is not necessarily limited to, a circuit including a high-speed clock, analog-to-digital (A / D) circuit, digital-to-analog (D / A) circuit, digital signal processor, or the like DSP, transceiver 26 . 36 and the necessary input / output (I / O) devices and other signal conditioning and / or buffer circuitry include, but are not limited to.

The TCM 20 and ECM 30 are programmed to perform the required steps of the startup control method, an example of which is shown in FIG 100 in 5 is shown, wherein the TCM 20 in particular a proportional, integral, differential (PID) based position control of the operation of a given input clutch C1 and C2 during the entire duration of starting the vehicle 10 offers. As part of the present approach control method, the ECM 30 generate various control values that a speed request of the engine (arrow N _ER ) for the control of the engine 12 and an acceleration _{value of} the engine (arrow I _☐ ), the latter of which is to the TCM 20 for use in a calculation of the TCM 20 which is hereinafter referred to as a calculated clutch torque. Ultimately, the TCM uses 20 the engine _{acceleration value} (arrow I _□ ), in particular the variance between engine torque and the calculated clutch torque, in maintaining the position control of the input clutch C1 or C2 and outputs a position control signal (arrow P _X ) to the particular input clutch C1 or C2 to thereby to control the position of the particular input clutch C1 or C2 in the manner described below.

With reference to 2 describes a set of line trains 50 various performance characteristics during startup of the in 1 shown vehicle 10 , In each of the traces the signal amplitude (A) is plotted on the vertical axis and time (t) is plotted on the horizontal axis. At the time t ₀ , a driver of the vehicle requests 10 a start by depressing the accelerator pedal 11 at. In response to the increased gas demand, a corresponding engine speed request is made by the ECM 30 generated, z. B. wherein the speed request of the engine is proportional to the gas demand (line Th% of 1 ).

When the engine speed request from the ECM 30 to the engine 12 is transmitted, the various actuators of the engine 12 from the ECM 30 controlled as necessary to provide a calibrated rate of engine acceleration. The actual torque of the engine (trace T _E ) increases, with the majority of this torque initially doing the work of increasing the speed of the engine (line N _E ). As is understood in the art, the actuators of the engine z. B. spark plugs and / or cylinders of the engine 12 be the ECM 30 controls the number of revolutions of the engine (line N _E ) by controlling the spark / ignition, the number of active cylinders, and so on.

Some of the actual torque of the engine (T _E) of the engine 12 is necessary to reduce the inertia (I) of the engine 12 to overcome, especially when starting. Moment of inertia of the engine (I) is used in the position control of various engine actuators. More specifically, a calculated torque (T _CALC ) may be determined by the TCM 20 be derived as follows: T _CALC = T _E - Iα where α is the measured or calculated acceleration of the engine 12 is and the other factors are described above. Any difference between the commanded clutch torque (T _CC ) from the TCM 20 and the calculated clutch _torque (T _CALC ) derived as set forth above is used to provide a closed loop correction of the clutch position of the particular input clutch C1 or C2 of FIG 1 represented DCT module 14 with a possible setting recorded on a TTP table or for the TCM 20 is accessible.

In 2 the speed of the engine (N _E ) increases when the accelerator pedal is depressed 11 strong before stabilizing at about t ₁ . Engine torque (T _E ) mainly accomplishes the work of increasing the engine speed (N _E ) in this initial interval t ₀ -t ₁ . At this start-up stage, high engine torque (T _E ) minus a large calculated inertia torque value (Iα) results in low calculated torque (T _CALC ). When the engine speed (N _E ) is a calibrated target, e.g. B. reached at about t ₁ , the torque of the engine (T _E ) may drop to the engine 12 to slow down, or there may be enough clutch torque (T _CC ) to accelerate the engine 12 to stop. The calculated torque (T _CALC ) increases to meet the commanded clutch torque (T _CC ). A deviation (Δ) of the calculated clutch _torque (T _CALC ) from the commanded clutch torque (T _CC ) causes the TCM 20 initiates control of the clutch position with the aim of matching T _CALC and T _CC .

The commanded clutch torque (trace T _CC ) may be used as a calibration value from the TCM 20 be delivered, for. From a look-up table or from a torque model stored in memory 23 is recorded, extracted. The TCM 20 thus monitors the actual torque of the engine (trace T _E ) and the moment of inertia of the engine ( _trace I _☐ ) to accurately determine how much load on the input _clutch C1 or C2 of the DCT assembly 14 from 1 during startup, and then sets the position signal (trace P _X of 3 ) as needed over time.

With reference to 3 becomes the clutch position signal (trace P _X ) from the TCM 20 from 1 generated and to the particular input clutch C1 or C2 of 1 , which is used to control the start of the vehicle, transmitted. As used herein, an "enlarged" clutch position signal is any position signal or position command that results in movement of a clutch engagement piston or other actuator in an engagement direction of the input clutch C1 or C2, and thus is a signal indicative of an input Increasing the clutch torque leads. Likewise, a "reduced" clutch position signal results in movement of a clutch engagement piston or other actuator in the release direction, and thus is a signal resulting in reduced clutch torque.

In an example control action in which a calculated clutch torque is the commanded clutch torque from the TCM 20 exceeds, the clutch position signal (trace P _X ) can be modified down to form polyline P _X ^- . A control action, in which the calculated clutch torque is less than the commanded clutch torque, the clutch position signal (trace P _X ) can be adjusted upward to form trace P _X ⁺ . At about t ₂ of 2 and 3 reaches the specific input clutch C1 or C2 synchronous speed, and the vehicle 10 is fully started, usually in first gear.

A setting of the clutch position signal (trace P _X ) of 3 can be used to automatically modify a recorded torque-to-position (TTP) table 60 an example of which is in 4 is shown, wherein the torque (T) is plotted on the horizontal axis and the position (P) is plotted on the vertical axis. The embodiment of 4 is a simple three-position TTP model that works in memory 23 of in 1 shown TCM 20 can be recorded. Such a table may be from the TCM 20 can be used to determine how much torque (T) to command precisely for a given clutch position (P), and vice versa. The TTP table 60 may include a calibrated minimum torque T ₁ , a calibrated torque T ₂ intermediate level, and a calibrated maximum torque T _{3 taken} together as a TTP trace 62 are illustrated. Each torque value corresponds in each case to a minimum clutch position, a middle-position clutch position or a maximum clutch position P ₁ , P ₂ or P ₃ . Thus, as part of a possible control action, the TCM may 20 the TTP table 60 modify or adapt over time, e.g. B. upwards in the direction of the arrow 65 as shown, is a customized TTP polyline 64 to be recorded for use in the next switching.

With reference to 5 begins an example procedure 100 for controlling a start of the in 1 shown vehicle 10 at step 102 , where the ECM 30 from 1 receives a gas signal (arrow Th%) indicating that a driver of the vehicle 10 the gas pedal 11 has depressed with sufficient force, thereby starting the vehicle 10 to request. The procedure 100 walk to step 104 when the gas signal (arrow Th%) has been detected.

step 104 brings about the derivation of the clutch _torque (T _CALC ), as explained above, such as the product of the known inertia (I) and the measured or calculated acceleration (α) of the engine 12 , The inertia (I) can be a calibrated value stored in memory 23 of the TCM 20 is recorded. The acceleration (α) can be determined using any suitable approach, e.g. By calculating the rate of change of a measured speed signal of the engine or by direct measurement. The calculated clutch _torque (T _CALC ) is recorded, and the procedure 100 then walk to step 108 continued.

At step 106 is the actual torque of the engine (trace T _E of 2 ). Such a value may in a particular embodiment of a torque model stored in memory 33 of the ECM 30 recorded, be available. So, for any given speed point, the torque is that of the engine 12 is issued and known to the TCM 20 reported, for example, via a Controller Area Network (CAN) bus.

At step 108 determines the TCM 20 Next, whether a commanded clutch torque, ie line T _CC of 2 , equal to the calculated clutch _torque (T _CALC ) of step 104 is, or at least within a small calibrated range of the calculated clutch _torque (T _CALC ). If this is the case, there is no adjustment to the clutch position signal (trace P _X of FIG 3 ) and the procedure 100 repeated step 102 , The steps 102 to 108 may continue in a loop until an exit condition signals a shift to a steady-state controller, which typically indicates completion of the startup as soon as the input clutch reaches synchronous speed. When the commanded clutch torque (trace T _CC of 2 ) is not equal to the calculated clutch _torque (T _CALC ), the procedure proceeds 100 instead to step 110 continued.

step 110 includes identifying through the TCM 20 whether the commanded clutch torque (trace T _CC ) is the calculated clutch _torque (T _CALC ) of step 104 exceeds. If this is the case, the procedure proceeds 100 to step 112 continued. Otherwise, the procedure proceeds 100 to step 114 continued.

At step 112 can the TCM 20 the clutch position signal (trace P _X of 3 ), ie, reduce the clutch position signal by a calibrated amount so that less clutch torque is applied to that position. step 112 may be adjusting a TTP table, e.g. For example, the example TTP table 60 from 4 , entail. The amount of adjustment may be limited by dead bands or other suitable limits to avoid congruence of the TTP model. For example, the position can not be reduced by more than 0.5 mm in each control loop in one possible approach, or by less than 2 mm in another embodiment. The procedure 100 returns after setting the position signal (trace P _X from 2 ) to step 102 back.

At step 114 represents the TCM 20 the clutch position signal (trace P _X of 3 ), ie, increases the clutch position signal by a calibrated amount so that more clutch torque is applied for that position. As with step 112 can step 114 modifying / adjusting the TTP table 60 from 4 to bring about a small calibrated amount. The procedure 100 returns after setting the clutch position signal (trace P _X of 2 ) or the TTP table 60 to step 102 back.

Using the method set out above 100 can the TCM 20 from 1 a speed request of the engine by requesting spark retard or gas control from the ECM 30 mix to match the acceleration rate of the vehicle 10 adapt. In other words, the calculated torque described above becomes the ECM 30 as a feedforward control term. In this way, the feel of starting is improved relative to conventional approaches. The TCM 20 ensures, via PID-based clutch position control during the entire start-up, that the clutch input torque of the input clutch C1 or C2 is as close as possible to the calculated clutch torque. The present approach will help prevent the TCM 20 commands a clutch torque to a high level, which could cause undesirable engine pull-down. Such an approach may include any change in the actual TTP characteristics of a given DCT over time, e.g. B. the DCT module 14 from 1 to handle better while still allowing maximum output torque through startup as the engine's torque capacity increases.

The detailed description and drawings or figures are supportive and descriptive of the invention, but the scope of the invention is defined only by the claims. Although the best mode, if any, and other embodiments for carrying out the claimed invention have been described in detail, there are various alternative constructions and embodiments for practicing the invention defined in the appended claims.

Claims (10)

A vehicle, comprising: an engine; an engine control module (ECM) in communication with the engine, the ECM providing an actual torque value of the engine; and a dual clutch transmission (DCT) assembly having first and second input clutches, first and second gear sets selectively connected to the engine via the respective first and second input clutches, and a transmission control module (TCM) coupled to the DCT assembly and communicating with the ECM and having a calibrated torque-to-position (TTP) table; wherein the TCM is configured to: receive a start request of the vehicle; receive the actual torque value of the engine from the ECM; determine an inertia torque value as the product of acceleration and inertia of the engine; calculate a clutch torque for a particular one of the first and second input clutches as a function of the actual torque value of the engine and the inertia torque value; calculate a difference between the calculated clutch torque and the commanded clutch torque; and to provide control of a position of the particular input clutch using the difference as a feedback term. The vehicle of claim 1, wherein the controller is configured to provide control of the position at least partially by extracting a clutch position from a torque-to-position (TTP) table and transmitting the clutch position signal to the particular input clutch. The vehicle of claim 2, wherein the controller is configured to modify the TTP table so that less clutch torque in the TTP table corresponds to a given engagement position of the particular input clutch when the calculated clutch torque exceeds the commanded clutch torque, and thus more clutch torque in the TTP table corresponds to the given engagement position if the calculated clutch torque is less than the commanded clutch torque. The vehicle of claim 1, wherein the ECM comprises a recorded torque model and configured to extract the actual torque value of the engine from the recorded torque model. The vehicle of claim 1, wherein the TCM is configured to detect when the input clutch reaches a synchronous speed and to transition to stationary control of the particular input clutch in the first gear when the input clutch reaches the synchronous speed. A dual clutch transmission (DCT) assembly for a vehicle having an engine with an engine control module (ECM), the DCT assembly comprising: a first and a second input clutch; a first and a second gear set, the first and second gear sets being selectively connected to the engine via the respective first and second input clutches; and a transmission control module (TCM) in communication with the ECM, the TCM configured to receive a startup request and further configured in response to the received startup request to: receive the actual torque value of the engine from the ECM; determine inertia and acceleration of the engine; calculate a clutch torque for a particular one of the first and second input clutches as a function of the actual torque value of the engine and the product of the inertia and acceleration of the engine; compare the calculated clutch torque with the commanded clutch torque; modify a recorded torque-to-position (TTP) table such that less clutch torque in the TTP table corresponds to a given engagement position of the particular input clutch when the calculated clutch torque exceeds the commanded clutch torque, and thus more clutch torque in the TTP Table corresponds to the given engagement position when the calculated clutch torque is less than the commanded clutch torque; and to transmit a clutch position signal to the particular input clutch to thereby command an engagement position extracted from the recorded TTP table. The DCT assembly of claim 6, wherein the DCT assembly is a dry DCT assembly characterized by an absence of circulation of cooling or lubricating fluid to the first and second input clutches. The DCT assembly of claim 6, wherein the input couplings are in fluid communication with a fluid pump and lubricated and cooled by fluid discharged from the fluid pump. The DCT assembly of claim 6, wherein the TCM is configured to detect when the particular input clutch reaches a synchronous speed and to transition to steady-state control of the particular input clutch in first gear when the input clutch reaches the synchronous speed. The DCT assembly of claim 6, wherein the first gear set establishes the odd-numbered gears of the DCT assembly, and the first input clutch is the particular input clutch for starting.

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