Method and system for controlling a clutch friction element and an automatic transmission vehicle

Abstract

The present application relates to a method and system for controlling a clutch friction element and an automatic transmission vehicle. A method and system for controlling a clutch friction element of an automatic transmission are provided. The method includes retrieving information about a shift clutch from a data storage unit and obtaining information required to predict the temperature of the friction element of each shift clutch; deriving a predicted temperature value of the friction element of each shift clutch by using the information about the shift clutch and the information required to predict the temperature of the friction element; predicting whether overheating occurs in each shift clutch by comparing the derived predicted temperature value of the friction element of each shift clutch with the allowable temperature setting of each shift clutch; and determining a target shift gear while avoiding an overheated clutch whose predicted temperature value exceeds the allowable temperature by switching to an avoidance shift mode.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10 - 2021 - 0047306, filed on April 12, 2021, the entire contents of which are incorporated herein by reference for all purposes. Technical field

[0003] The present invention relates to a control method and system for protecting a clutch friction element of an automatic transmission, and particularly to a control method and system for predicting overheating of a shift clutch constituting an automatic transmission and protecting the shift clutch from overheating and subsequent damage or breakage through predetermined control, and an automatic transmission vehicle including the system. Background art

[0004] Generally, an automatic transmission is a mechanical device that can automatically obtain an optimal gear shift according to the driving speed and load of a vehicle. Such an automatic transmission is configured to change the gear shift gear position by operating a shift solenoid and a shift clutch (hereinafter referred to as "clutch") under the control of a transmission control unit (TCU) that outputs a shift control command according to a driver's request or the driving state of the vehicle.

[0005] A transmission control unit for controlling an automatic transmission uses a shift map (shift pattern) set according to the relationship between the amount of pedal depression of an accelerator pedal and the vehicle speed to find an optimal gear shift position that matches the amount of pedal depression and the vehicle speed. Then, the gear shift position is set as a target gear shift position, and a target oil pressure (solenoid duty value) for shifting to the target gear shift position is determined, and based on this, the shift solenoid is controlled.

[0006] When oil is supplied to the clutch related to the target gear shift position according to the operation of the shift solenoid, the clutch is operated to the engaged side, thereby achieving the target gear shift. Here, in a case where the amount of oil supplied to the clutch is less than the required level or the torque fluctuation is large, such as in a downshift, excessive slippage occurs between the clutch friction elements (discs and plates), resulting in overheating or severe damage of the clutch.

[0007] However, since the prior art has no technology to prevent overheating and subsequent damage of the clutch friction elements (discs and plates) due to excessive slippage between the clutch friction elements in a case where the amount of oil supplied to the clutch is less than the required level or the torque fluctuation is large, such as in a downshift, it is necessary to address this point.

[0008] The foregoing is merely to assist in understanding the background of the present disclosure and is not intended to mean that the present disclosure falls within the scope of related art known to those skilled in the art. Summary of the invention

[0009] In one aspect, a control method and system for protecting a clutch friction element of an automatic transmission, and an automatic transmission vehicle including the control system are provided, wherein overheating of a shift clutch is predicted in real time based on various information collected from various parts of the vehicle, and when a specific shift clutch is predicted to overheat, predetermined control (shift avoidance, engine torque limitation, etc.) is performed to protect the shift clutch from overheating and damage caused thereby.

[0010] In one aspect of the present disclosure, a method for controlling a clutch friction element of an automatic transmission is provided, the method comprising:

[0011] (a) Retrieving information about a shift clutch from a data storage unit and obtaining information required to predict the temperature of a friction element of each shift clutch;

[0012] (b) Deriving a predicted temperature value of a friction element of each shift clutch by using the information about the shift clutch and the information required to predict the temperature of the friction element;

[0013] (c) Predicting whether overheating occurs in each shift clutch by comparing the derived predicted temperature value of a friction element of each shift clutch with an allowable temperature setting of each shift clutch; and

[0014] (d) Determining a target shift gear while switching to a shift avoidance mode to avoid an overheated clutch whose predicted temperature value exceeds the allowable temperature.

[0015] In some preferred aspects, the information required to predict the temperature of a friction element of each shift clutch may include some or all of the rotational speed of an oil pump or a torque converter turbine, oil temperature, current shift gear, oil supply flow rate of each shift clutch, rotational speeds of a clutch hub and a clutch drum of each shift clutch corresponding to the rotational speed of the turbine, and target hydraulic pressure of each shift clutch.

[0016] Preferably, in step (b), the predicted temperature value of the friction element of each shift clutch can be derived through the following steps: Determine the rotational speed and relative speed of the clutch hub and clutch drum of each shift clutch corresponding to the current turbine rotational speed according to the clutch speed map set based on the relationship between the rotational speeds of the turbine and the clutch hub and clutch drum of each shift clutch; use the oil flow map to determine the current rotational speed of the oil pump or the turbine rotational speed and the oil temperature, as well as the oil supply flow rate of each shift clutch corresponding to the current shift gear; use the clutch torque map to determine the estimated transmission torque of each shift clutch, which uses the piston acting pressure derived from the target hydraulic pressure of each shift clutch and the moment of inertia of the friction element as factors, and use the heat value map set based on the relationship between the estimated transmission torque of each shift clutch and the relative speed between the clutch hub and the clutch drum to derive the heat value of the friction element of each shift clutch, and finally, use the friction element temperature map set based on the relationship between the heat value of the friction element of each shift clutch and the oil supply flow rate of each shift clutch to determine the predicted temperature value of the friction element of each shift clutch corresponding to the oil supply flow rate of each shift clutch and the heat value of the friction element of each shift clutch.

[0017] In some preferred aspects, when the mode is switched to the avoidance shift mode, when an input shift command is given, the target shift gear can be determined while avoiding identifying the shift clutch as an overheated clutch.

[0018] The control method may further include:

[0019] (e) Compare the predicted temperature value of the friction element with a reference temperature obtained by adding a specific value to the current oil temperature in the state of switching to the avoidance shift mode, and determine whether to take additional protection measures; and

[0020] (f) Determine the final target hydraulic pressure of the target shift gear.

[0021] Preferably, as a result of the comparison in step (e), if the predicted temperature value of the friction element is equal to or greater than the reference temperature, then in step (f), after taking protection measures for additional limiting the engine torque to protect the friction element, the final target hydraulic pressure of the target shift gear can be derived. In addition, when the predicted temperature value of the friction element is less than the reference temperature, in step (f), the final target hydraulic pressure of the target shift gear can be directly derived without taking protection measures for additional limiting the engine torque to protect the friction element.

[0022] In some aspects, additional engine torque limitation for protecting friction elements can be achieved by a process of using a torque limitation map (where different torque limitation values are stored according to predicted temperature values of friction elements and oil temperature), determining a limiting torque corresponding to the predicted temperature value of the friction element of each shift clutch and the current oil temperature, and controlling the engine output so as not to exceed the determined limiting torque.

[0023] Furthermore, the final target hydraulic pressure can be derived by adding a hydraulic compensation value determined in a hydraulic compensation map having oil temperature, throttle opening (% ), coolant temperature, and load as factors to a base hydraulic value determined according to engine torque.

[0024] On the other hand, a system for controlling a clutch friction element of an automatic transmission is provided, the system including:

[0025] A data storage unit configured to store information about shift clutches;

[0026] A data collection unit configured to collect information required for predicting the temperature of the friction element of each shift clutch; and

[0027] A transmission control unit (TCU) configured to perform transmission control by using the information about shift clutches and the information required for predicting the friction element temperature, the TCU including;

[0028] A plurality of processors programmed to predict overheating of the friction element of each shift clutch by predicting the temperature of the friction element of each shift clutch by using the information about shift clutches and the information required for predicting the friction element temperature, and control shifting while avoiding the shift clutch being predicted to be overheated.

[0029] Preferably, the plurality of processors may include: a predicted temperature derivation section configured to derive a predicted temperature value of the friction element of each shift clutch by using the information about shift clutches and the information required for predicting the friction element temperature; an overheat determination section configured to predict whether overheating occurs in each shift clutch by comparing the derived predicted temperature value of the friction element of each shift clutch with the allowable temperature setting of each shift clutch; a protection logic operation section having a shift avoidance logic configured to identify the shift clutch predicted to be overheated as an overheated clutch and determine the shift gear while avoiding identifying the shift clutch as an overheated clutch; and a hydraulic control section configured to derive a final target hydraulic pressure for shifting to a target shift gear and perform transmission control based on the derived final target hydraulic pressure.

[0030] In some aspects, the predicted temperature derivation section may derive the predicted temperature value of the friction element of each shift clutch through the following steps: Determine the rotational speed and relative speed of the clutch hub and clutch drum of each shift clutch corresponding to the current turbine rotational speed according to the clutch speed map set based on the relationship between the rotational speeds of the turbine and the clutch hub and clutch drum of each shift clutch, use the oil flow map to determine the current rotational speed of the oil pump or the turbine rotational speed and oil temperature, and the oil supply flow rate of each shift clutch corresponding to the current shift gear, use the clutch torque map to determine the estimated transmission torque of each shift clutch, which uses the piston acting pressure derived from the target hydraulic pressure of each shift clutch and the moment of inertia of the friction element as factors, and use the heat value map set based on the relationship between the estimated transmission torque of each shift clutch and the relative speed between the clutch hub and clutch drum to derive the heat value of the friction element of each shift clutch, and finally, use the friction element temperature map set based on the relationship between the heat value of the friction element of each shift clutch and the oil supply flow rate of each shift clutch to determine the predicted temperature value of the friction element of each shift clutch corresponding to the oil supply flow rate of each shift clutch and the heat value of the friction element of each shift clutch.

[0031] In addition, the protection logic operation section may further include torque limit logic configured to compare the predicted temperature value of the friction element with a reference temperature obtained by adding a specific value to the current oil temperature (and when the predicted temperature value of the friction element is equal to or greater than the reference temperature) to additionally limit the engine torque to protect the friction element.

[0032] One or more of the above steps and configurations may be performed by using a processor or a control unit.

[0033] In another aspect of the present invention, an automatic transmission vehicle is provided, including a control system for protecting the clutch friction elements of an automatic transmission according to the aspects of the present invention.

[0034] In some additional aspects, based on various information collected from each part of the vehicle, overheating of the shift clutch, more specifically, overheating of the clutch friction element, is predicted in real time. Then, when overheating is predicted in the friction element of a specific shift clutch, reliable prevention of overheating of the specific shift clutch and the resulting damage can be achieved by performing predetermined control (such as avoiding shifting, engine torque limitation, etc.).

[0035] Other aspects are disclosed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a block diagram schematically showing the system configuration of a control system for protecting the clutch friction elements of an automatic transmission according to an embodiment of the present disclosure;

[0037] Figure 2 is a flowchart schematically showing a control process for protecting a clutch friction element of an automatic transmission; and

[0038] Figure 3 is a control flowchart specifically showing a control process for protecting a clutch friction element of an automatic transmission. Detailed Description of the Invention

[0039] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0040] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. As used herein, an element expressed in the singular form includes a plurality of elements unless the context clearly indicates otherwise.

[0041] In addition, it will be understood that the terms "comprises" or "comprising" specify the presence of the stated features, numbers, steps, operations, elements, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, parts, or combinations thereof.

[0042] In addition, terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are only for the purpose of distinguishing one component from another.

[0043] In addition, terms such as "... part", "... unit", "... module" described in this specification refer to a unit that processes at least one function or operation, and the function or operation can be implemented by hardware or software or a combination of hardware and software.

[0044] In addition, the control logic of the present disclosure can be implemented as a non-transitory computer-readable medium on a computer-readable medium, including executable program instructions executed by a processor, a controller, etc. Examples of computer-readable media include, but are not limited to, ROM, RAM, compact disc (CD)-ROM, magnetic tape, floppy disk, flash drive, smart card, and optical data storage device. The computer-readable medium can also be distributed in a network-coupled computer system so that the computer-readable medium is stored and executed in a distributed manner (e.g., by a telematics server or a controller area network (CAN)).

[0045] It should be understood that the term "vehicle" or "vehicular" or other similar terms used herein generally include motor vehicles, such as passenger cars including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, vessels including various boats and ships, airplanes, etc., and include hybrid vehicles, electric vehicles, plug-in hybrid vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels from resources other than petroleum). As described herein, a hybrid vehicle is a vehicle having two or more power sources, e.g., a gasoline-powered vehicle and an electric-powered vehicle.

[0046] In the description with reference to the drawings, it is noted that the same elements are denoted by the same reference symbols in the drawings, and repeated descriptions of the same structures will be omitted. In addition, detailed descriptions of known functions and configurations that may obscure the gist of the present disclosure will be omitted.

[0047] The present disclosure is provided to predict in real time overheating of a shift clutch based on various information collected from each part of a vehicle, and when overheating is predicted in a specific shift clutch, to protect the specific shift clutch from overheating and damage caused thereby by performing predetermined control (such as avoiding shifting, engine torque limitation, etc.). Reference will be made to Figure 1 Describe the configuration of a control system for protecting a clutch friction element of an automatic transmission.

[0048] Figure 1 is a block diagram schematically showing the system configuration of a control system for protecting a clutch friction element of an automatic transmission according to an embodiment of the present disclosure.

[0049] Referring to Figure 1 , a control system 1 for protecting a clutch friction element according to an embodiment of the present invention includes: a data storage unit 10 configured to store information about a plurality of shift clutches constituting an automatic transmission, a data collection unit 20 configured to collect information required to predict the temperature of a friction element of each shift clutch, and a transmission control unit (TCU) 30 configured to control the transmission using the information about the shift clutch and the information required to predict the temperature of the friction element.

[0050] Here, the information about the shift clutch stored in the data storage unit 10 may be information about the entire clutch specification, such as the number of clutch friction elements (the number of clutch discs and clutch plates) and the diameter of the friction element of each shift clutch, and the overlapping area of adjacent friction elements (of the clutch discs and clutch plates), i.e., the actual friction area between adjacent friction elements.

[0051] In addition, the information collected by the data collection unit 20 to predict the friction element temperature of each shift clutch may include some or all of the rotational speed of the oil pump or torque converter turbine, the oil temperature, the current shift gear, the oil supply flow rate of each shift clutch, the rotational speed of the clutch hub and clutch drum of each shift clutch corresponding to the rotational speed of the turbine, and the target hydraulic pressure of each shift clutch.

[0052] The transmission control unit 30 is configured to predict overheating of the friction elements of each shift clutch by predicting the temperature of the friction elements of each shift clutch, respectively using the information about the shift clutches and the information required to predict the temperature of the friction elements provided by the data storage unit 10 and the data collection unit 20. The transmission control unit includes a plurality of processors programmed to sequentially execute a series of processes to control shifting while avoiding shift clutches predicted to be overheated.

[0053] The plurality of processors of the TCU 30 constituting the control system preferably include a predicted temperature derivation section 32 (configured to derive a predicted temperature value of the friction element of each shift clutch), and an overheat determination section 34 (configured to predict whether overheating occurs in each shift clutch by comparing the predicted temperature value of the friction element of each shift clutch with the allowable temperature setting of each shift clutch).

[0054] In addition, the processor includes a protection logic operation section 36 having an avoidance shift logic configured to identify a shift clutch predicted to be overheated as an overheated clutch and determine a shift gear while avoiding identifying the shift clutch as an overheated clutch, and a hydraulic control section 38 configured to derive a final target hydraulic pressure for shifting to a target shift gear and perform transmission control based on the derived final target hydraulic pressure.

[0055] The predicted temperature derivation section 32 derives a predicted temperature value of the friction element of each shift clutch using the information about the shift clutch and the information required to predict the temperature of the friction element. In the predicted temperature derivation section 32, the process of deriving the predicted temperature value of the friction element of each shift clutch using the information about the shift clutch and the information required to predict the temperature of the friction element is as follows.

[0056] Process for deriving the predicted temperature of the friction elements of each shift clutch

[0057] 1. Determine the rotational speed and relative speed of the clutch hub and clutch drum of each shift clutch corresponding to the current turbine rotational speed according to the clutch speed map set based on the relationship between the rotational speeds of the turbine and the clutch hub and clutch drum of each shift clutch

[0058] 2. Use the oil flow diagram to determine the current rotational speed of the oil pump or the turbine rotational speed and the oil temperature, as well as the oil supply flow rate for each shift clutch corresponding to the current shift gear

[0059] 3. Use the clutch torque diagram to determine the estimated transmission torque for each shift clutch, which uses the piston acting pressure derived from the target hydraulic pressure of each shift clutch and the moment of inertia of the friction element as factors, and use the heat value diagram set by the relationship between the estimated transmission torque of each shift clutch and the relative speed between the clutch hub and the clutch drum to derive the heat value of the friction element of each shift clutch

[0060] 4. Finally, use the friction element temperature diagram set by the relationship between the heat value of the friction element of each shift clutch and the oil supply flow rate of each shift clutch to determine the predicted temperature value of the friction element of each shift clutch corresponding to the oil supply flow rate of each shift clutch and the heat value of the friction element of each shift clutch

[0061] The information on the predicted temperature value of the friction element of each shift clutch derived by the predicted temperature derivation section 32 through the above series of processes is provided to the overheat determination unit 34, which determines whether overheating has occurred by comparing the predicted temperature value of the friction element of each shift clutch provided by the predicted temperature derivation section 32 with the allowable temperature setting for each shift clutch (a reference value for determining overheating of the friction element of each shift clutch).

[0062] Specifically, when the predicted temperature value of the friction element of each shift clutch exceeds the corresponding set allowable temperature (a reference value for determining overheating of the friction element of each shift clutch), the overheat determination section 34 determines (predicts) that the shift clutch with the predicted temperature value has overheated. More precisely, when the predicted temperature value of the friction element exceeds the allowable temperature, it is predicted that excessive slippage occurs during shifting of the corresponding shift clutch, resulting in overheating.

[0063] The determination information of the overheat determination section 34 is provided to the protection logic operation section 36. Based on the determination information provided by the overheat determination section 34, the protection logic operation section 36 identifies the shift clutch predicted to be overheated due to excessive slippage during shifting as an overheated clutch. In addition, when a shift request is received, the protection logic operation section determines the target shift gear while avoiding identifying the shift clutch as an overheated clutch, thereby preventing clutch overheating.

[0064] For example, during an 8-speed drive, when a forced downshift is required due to a sudden operation of the accelerator pedal and the target shift gear determined on a dedicated shift map based on the current accelerator pedal depression amount and vehicle speed is 5th gear (8th gear → 5th gear), if the temperature of the shift clutch applied when changing the shift gear to 5th gear exceeds the allowable temperature, the target shift gear is changed from 5th gear to 6th gear to avoid overheating of the corresponding shift clutch.

[0065] The protection logic operation section 36 also includes torque limit logic for additionally limiting the engine torque to protect the friction elements. Here, the torque limit logic can be programmed to compare the predicted temperature value of the friction elements of each shift clutch with a reference temperature obtained by adding a specific value to the current oil temperature (e.g., oil temperature + 5°C), and when the predicted temperature value of the friction elements is equal to or greater than the reference temperature, limit the engine torque within a set range.

[0066] On the other hand, when the target shift gear finally determined by a dedicated shift map set based on the relationship between the accelerator pedal depression amount and the vehicle speed or the final target to be avoided by the protection logic operation section 36 is determined, the hydraulic control section 38 derives the final target hydraulic pressure for shifting to the target shift gear and controls the shift solenoid based on the derived final target hydraulic pressure to perform the shift.

[0067] Here, the final target hydraulic pressure can be derived by adding a hydraulic compensation value determined in a hydraulic compensation map having oil temperature, throttle opening (%), coolant temperature, and load as factors to a base hydraulic pressure value determined based on the engine torque. That is, the final target hydraulic pressure for shifting to the target shift gear can be determined as a value obtained by adding the hydraulic compensation value to the base hydraulic pressure value.

[0068] Reference will be made to Figure 2 the control flowcharts shown in to describe the sequential control process for protecting the clutch friction elements of an automatic transmission using the control system for protecting the clutch friction elements according to an embodiment of the present disclosure. For ease of explanation, the configuration shown in will be described with reference to the corresponding reference numerals. Figure 1 in.

[0069] Figure 2 is a flowchart schematically showing the control process for protecting the clutch friction elements of an automatic transmission, and Figure 3 is a control flowchart specifically showing the control process for protecting the clutch friction elements of an automatic transmission.

[0070] Refer to Figure 2 and Figure 3, the control method for protecting the clutch friction elements of an automatic transmission according to an embodiment of the present disclosure mainly includes an information acquisition step S100, a predicted temperature derivation step S200, an overheat prediction step S300, and a protection logic drive step S400. In addition, the control method may further include an additional protection logic drive determination step S500, an additional protection logic drive step S600, and a final target hydraulic pressure determination step S700.

[0071] In the information acquisition step S100, information about the shift clutch is obtained from the data storage unit 10, and information required to predict the temperature of the friction elements of each shift clutch is obtained.

[0072] Here, the information about the shift clutch may be information about the entire clutch specifications, such as the number of clutch friction elements (the number of clutch discs and clutch plates) and the diameter of the friction elements of each shift clutch, as well as the overlapping area (of the clutch discs and clutch plates) of adjacent friction elements, that is, the actual friction area between adjacent friction elements.

[0073] In addition, the information required to predict the temperature of the friction elements of each shift clutch may include some or all of the rotational speed of the oil pump or the torque converter turbine, the oil temperature, the current shift gear, the oil supply flow rate of each shift clutch, the rotational speeds of the clutch hub and the clutch drum of each shift clutch corresponding to the rotational speed of the turbine, and the target hydraulic pressure of each shift clutch.

[0074] In the predicted temperature derivation step S200, using the information about the shift clutch obtained in the information acquisition step S100 and the information required to predict the friction element temperature, the predicted temperature value of the friction elements of each shift clutch is derived. Since the detailed process of deriving the predicted temperature value of the friction elements for each shift clutch in the predicted temperature derivation step S200 has been described above, redundant descriptions will be omitted below.

[0075] In the overheat prediction step S300, by comparing the predicted temperature value of the friction elements of each shift clutch derived through the predicted temperature derivation step S200 with the allowable temperature set for each shift clutch (the reference value for determining overheating of the friction elements of each shift clutch), it is predicted whether each shift clutch will overheat. In the overheat prediction step S300, when the predicted temperature value exceeds the allowable temperature, it is predicted that the corresponding shift clutch will overheat during the shift process.

[0076] When overheat is not predicted in any of the shift clutches in the overheat prediction step S300, that is, when the predicted temperature value is lower than the allowable temperature, shifting is performed by executing hydraulic control according to the target shift gear determined based on the pedal depression amount of the accelerator pedal and the vehicle speed on the shift map, without performing additional processing. When overheat is predicted in a specific shift clutch, the process proceeds to the protection logic drive step S400.

[0077] In the protection logic drive step S400, the operation mode is switched to an avoidance shift mode that avoids the overheat clutch having a predicted temperature value exceeding the allowable temperature. Specifically, when a shift command is input when switching to the avoidance shift mode, the target shift gear is determined by avoiding identifying the shift clutch as the overheat clutch, thereby preventing the corresponding clutch (the clutch identified as the overheat clutch) from overheating in advance.

[0078] For example, during 8th gear driving, when forced downshifting is required due to a sudden operation of the accelerator pedal and the target shift gear determined on the dedicated shift map based on the current pedal depression amount of the accelerator pedal and the vehicle speed is 5th gear (8th gear → 5th gear), when the temperature of the shift clutch applied when changing the shift gear to 5th gear exceeds the allowable temperature, the target shift gear is changed from 5th gear to 6th gear to avoid overheating of the corresponding shift clutch.

[0079] In the additional protection logic operation determination step S500, it is determined whether to take additional protection measures by comparing the predicted temperature value of the friction element with a reference temperature obtained by adding a specific value to the current oil temperature in the state where the mode was switched to the avoidance shift mode in the previous step S400. Here, the additional protection measures can be measures for protecting the friction element of the shift clutch involved when changing the target shift gear by engine torque limitation shifting.

[0080] As a result of the comparison in the additional protection logic drive determination step S500, when the predicted temperature value of the friction element is equal to or greater than the reference temperature, after taking protection measures to additionally limit the engine torque to protect the friction element (additional protection logic drive step S600), the process proceeds to the final target hydraulic pressure determination step S700 for deriving the final target hydraulic pressure of the target shift gear.

[0081] At this time, when additionally limiting the engine torque to protect the friction element in the additional protection logic drive step S600, in cooperation with the ECU, the limit torque and engine output corresponding to the predicted temperature value of the friction element of each shift clutch and the current oil temperature are controlled using a torque limitation map (where different torque limitation values are stored according to the predicted temperature value of the friction element and the oil temperature) so as not to exceed the determined limit torque.

[0082] On the contrary, if the predicted temperature value of the friction element is less than the reference temperature as a result of the comparison in step S500 determined by the additional protection logic operation, the final target hydraulic pressure for shifting to the target shift gear is directly derived without the need for additional protection measures to limit the engine torque to protect the friction element. That is, step S600 is omitted, and the process proceeds directly from step S500 to step S700.

[0083] Meanwhile, in the final target hydraulic pressure determination step S600, when the target shift gear is finally determined through the dedicated shift map or the final target shift gear avoided by the above protection logic operation section 36 is determined, the final target hydraulic pressure for shifting to the target shift gear is derived.

[0084] Here, the final target hydraulic pressure can be derived by adding the hydraulic compensation value determined in the hydraulic compensation map with the oil temperature, throttle opening (%), coolant temperature, and load as factors to the base hydraulic value determined according to the engine torque. That is, the final target hydraulic pressure for shifting to the target shift gear can be determined as the value obtained by adding the hydraulic compensation value to the base hydraulic value.

[0085] According to an embodiment of the present disclosure, based on various information collected from each part of the vehicle, overheating of the shift clutch, more specifically, overheating of the clutch friction element, is predicted in real time. Then, when overheating is predicted in the friction element of a specific shift clutch, reliable prevention of overheating and damage caused thereby of the specific shift clutch can be achieved by performing predetermined control (avoiding shifting, engine torque limitation, etc.).

[0086] In the above detailed description of the present disclosure, only specific embodiments thereof are described. However, it should be understood that the present disclosure is not limited to the specific forms described in the detailed description, but should be understood to cover all modifications, equivalents, and substitutions falling within the spirit and scope of the present disclosure defined by the appended claims.

Claims

1. A method for controlling a clutch friction element of an automatic transmission, the method comprising: a Retrieving information about a shift clutch from a data storage unit and obtaining information required to predict the temperature of the friction element of each shift clutch; b Deriving a predicted temperature value of the friction element of each shift clutch by using the information about the shift clutch and the information required to predict the temperature of the friction element; c Predicting whether overheating occurs in each shift clutch by comparing the derived predicted temperature value of the friction element of each shift clutch with the allowable temperature setting of each shift clutch; d Determining a target shift gear while avoiding the overheated clutch whose predicted temperature value exceeds the allowable temperature by switching to an avoidance shift mode; e Determining whether to take additional protection measures by comparing the predicted temperature value of the friction element with a reference temperature obtained by adding a specific value to the current oil temperature in a state where the avoidance shift mode is switched; And f Determining the final target hydraulic pressure of the target shift gear.

2. The method according to claim 1, wherein, The information required to predict the temperature of the friction element of each shift clutch includes some or all of the rotational speed of an oil pump or a torque converter turbine, the oil temperature, the current shift gear, the oil supply flow rate of each shift clutch, the rotational speeds of the clutch hub and the clutch drum of each shift clutch corresponding to the rotational speed of the turbine, and the target hydraulic pressure of each shift clutch.

3. The method according to claim 1, wherein In step b, the predicted temperature value of the friction element of each shift clutch is derived by the following steps: Determining the rotational speed and relative speed of the clutch hub and the clutch drum of each shift clutch corresponding to the current turbine rotational speed according to a clutch speed map set based on the relationship between the rotational speeds of the turbine, the clutch hub and the clutch drum of each shift clutch; Determining the current rotational speed of the oil pump or the turbine rotational speed, the oil temperature, and the oil supply flow rate of each shift clutch corresponding to the current shift gear by using an oil flow map; Determining the estimated transmission torque of each shift clutch by using a clutch torque map, the clutch torque map using the piston acting pressure derived from the target hydraulic pressure of each shift clutch and the moment of inertia of the friction element as factors, and deriving the heat value of the friction element of each shift clutch by using a heat value map set based on the relationship between the estimated transmission torque of each shift clutch and the relative speed between the clutch hub and the clutch drum; And Finally, determining the predicted temperature value of the friction element of each shift clutch corresponding to the oil supply flow rate of each shift clutch and the heat value of the friction element of each shift clutch by using a friction element temperature map set based on the relationship between the heat value of the friction element of each shift clutch and the oil supply flow rate of each shift clutch.

4. The method according to claim 1, wherein When the mode is switched to the avoidance shift mode, when an input shift command is given, the target shift gear is determined while avoiding the shift clutch identified as the overheated clutch.

5. The method according to claim 1, wherein, When the predicted temperature value of the friction element is equal to or greater than the reference temperature, after taking protective measures for additionally restricting the engine torque to protect the friction element, the final target hydraulic pressure for the target shift gear is derived, and when the predicted temperature value of the friction element is less than the reference temperature, the final target hydraulic pressure for the target shift gear is directly derived without taking the protective measures for additionally restricting the engine torque to protect the friction element.

6. The method according to claim 5, wherein The additional engine torque restriction for protecting the friction element is achieved by using a torque restriction map to determine a restriction torque corresponding to the predicted temperature value of the friction element of each shift clutch and the current oil temperature, and controlling the engine output so as not to exceed the determined restriction torque. In the torque restriction map, different torque restriction values are stored according to the predicted temperature value of the friction element and the oil temperature.

7. The method according to claim 5, wherein The final target hydraulic pressure is derived by adding a hydraulic compensation value determined in a hydraulic compensation map having the oil temperature, throttle opening %, coolant temperature, and load as factors to a base hydraulic pressure value determined according to the engine torque.

8. A system for controlling a clutch friction element of an automatic transmission, the system comprising: a data storage unit configured to store information about a shift clutch; a data collection unit configured to collect information required for predicting the temperature of the friction element of each shift clutch; and a transmission control unit TCU configured to perform transmission control by using the information about the shift clutch and the information required for predicting the friction element temperature. The TCU includes: a plurality of processors programmed to predict overheating of the friction element of each shift clutch by predicting the temperature of the friction element of each shift clutch by using the information about the shift clutch and the information required for predicting the temperature of the friction element, and to control shifting while avoiding the shift clutch predicted to be overheated. Among them, the plurality of processors include: a predicted temperature derivation part configured to derive a predicted temperature value of the friction element of each shift clutch by using the information about the shift clutch and the information required for predicting the temperature of the friction element; an overheating determination part configured to predict whether overheating occurs in each shift clutch by comparing the derived predicted temperature value of the friction element of each shift clutch with the allowable temperature setting of each shift clutch; a protection logic operation part having a shift avoidance logic configured to identify the shift clutch predicted to be overheated as an overheated clutch and to determine a shift gear while avoiding the shift clutch identified as the overheated clutch; and a hydraulic control part configured to derive a final target hydraulic pressure for shifting to a target shift gear and to perform transmission control based on the derived final target hydraulic pressure, wherein the predicted temperature derivation part derives the predicted temperature value of the friction element of each shift clutch through the following steps: Based on the clutch speed map set according to the relationship between the rotational speeds of the turbine, clutch hub, and clutch drum of each shift clutch, determine the rotational speed and relative speed of the clutch hub and the clutch drum of each shift clutch corresponding to the current turbine rotational speed; Use the oil flow map to determine the current rotational speed of the oil pump or the turbine rotational speed, the oil temperature, and the oil supply flow rate of each shift clutch corresponding to the current shift gear; Use the clutch torque map to determine the estimated transmission torque of each shift clutch. The clutch torque map uses the piston acting pressure derived from the target hydraulic pressure of each shift clutch and the moment of inertia of the friction element as factors, and uses the heat value map set according to the relationship between the estimated transmission torque of each shift clutch and the relative speed between the clutch hub and the clutch drum to derive the heat value of the friction element of each shift clutch; and Finally, use the friction element temperature map set according to the relationship between the heat value of the friction element of each shift clutch and the oil supply flow rate of each shift clutch to determine the predicted temperature value of the friction element of each shift clutch corresponding to the oil supply flow rate of each shift clutch and the heat value of the friction element of each shift clutch.

9. The system according to claim 8, wherein, The protection logic operation part further includes torque limit logic, which is configured to compare the predicted temperature value of the friction element with a reference temperature obtained by adding a specific value to the current oil temperature, and when the predicted temperature value of the friction element is equal to or greater than the reference temperature, additionally limit the engine torque to protect the friction element.

10. An automatic transmission vehicle, comprising a system for controlling the clutch friction element of an automatic transmission according to claim 8.

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