Method and system for controlling gear shifting in response to changes in driving mode

Abstract

A method and system for controlling shifting in response to a change in driving mode are provided. In one aspect, a method for controlling shifting in response to a change in driving mode includes: determining a maximum number of allowable low-speed shifting steps based on a result of determining a state of a transmission; calculating an expected turbine speed immediately after shifting for each step included in the maximum number of allowable low-speed shifting steps using a current speed of an output shaft of the transmission and a gear ratio of each step, and comparing the calculated expected turbine speed with a preset allowable speed for each step; setting the lowest-level shifting step among the shifting steps in which the expected turbine speed and the allowable speed satisfy predetermined conditions as a target shifting step; and executing shift control to reduce the current shifting step to the target shifting step.

Description

[0001] Cross-citation to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2021-0047283, filed on Apr. 12, 2021, which is hereby incorporated herein in its entirety for all purposes of this reference. Technical Field

[0003] The present disclosure relates to a method and system for controlling gear shifting in response to a change in driving mode, and more specifically, to a method and system for controlling gear shifting in response to a change in driving mode, the method and system being capable of controlling gear shifting when switching from an operating mode other than a sport mode (e.g., an ECO mode, a normal mode, a comfort mode, etc.) to a sport mode during driving, and an automatic transmission vehicle including a system for controlling gear shifting in response to a change in driving mode. Background Art

[0004] Generally, an automatic transmission is a mechanical device that automatically achieves the optimal torque conversion result based on the vehicle's driving speed and load. Automatic transmissions are configured so that gears are shifted by operating shift solenoids and clutches under the control of a transmission control unit (TCU). The TCU outputs shift control commands based on the driver's request or the vehicle's driving conditions.

[0005] The transmission control unit (TCU) that controls the automatic transmission receives information about the vehicle's status from the engine control unit (ECU). Based on this information, it outputs control commands for the shift solenoids and clutches to execute gear shifts. Furthermore, the TCU requests output changes from the ECU at the timing of gear shifts, based on the operation of the shift solenoids and clutches.

[0006] For example, when the driver depresses the accelerator pedal to accelerate the vehicle, the transmission control unit requests the engine control unit to reduce the engine torque in order to perform a smooth upshift or downshift operation. Then, after requesting the engine torque reduction, a request to increase the engine torque is output to the engine control unit in order to synchronize the rotational speed of the input shaft of the automatic transmission with the rotational speed of the output shaft of the engine.

[0007] The shift control unit also uses a shift pattern (shift map) configured based on the relationship between the amount of work applied to the accelerator pedal and the output speed of the transmission (i.e., vehicle speed) to determine an optimal shift step suitable for the amount of work applied to the accelerator pedal and the speed of the traveling vehicle. The optimal shift step is then set as a target shift step, and a target hydraulic pressure (solenoid duty value) for shifting to the target shift step is determined. The shift solenoid is controlled based on the target hydraulic pressure.

[0008] Automatic transmission vehicles that meet predetermined specifications have a drive mode selection function. The driver can select the desired drive mode using a dedicated switch with this function installed in a suitable location within the vehicle. When a drive mode is selected, the shift pattern matching the selected drive mode is retrieved, and gear shifts are performed accordingly. This allows for increased vehicle responsiveness and a different shift feel tailored to the driver's preference.

[0009] Typically, selectable driving modes include ECO, Normal, Comfort, and Sport, depending on the vehicle type. Sport mode, among other modes, sets the reference point for gear shifting to a higher speed than in other modes. Shifting to a higher gear is performed when the vehicle has sufficient driving force, at the expense of fuel efficiency. As a result, the driver can enjoy a more dynamic driving experience and experience increased vehicle responsiveness.

[0010] However, when a change in driving mode to sport mode occurs during driving, shifting is uniformly performed according to the shift reference points set in a sport mode-specific shift pattern (a sport mode-specific shift map having the following factors: vehicle speed and pedal work).

[0011] The above content is only intended to help understanding the background of the present disclosure, but does not mean that the present disclosure belongs to the scope of the relevant fields known to those skilled in the art. Summary of the Invention

[0012] In one aspect, a method and system for controlling gear shifting in response to a change in driving mode are now provided, which can perform downshifting by setting a target gear shift step to a gear shift step lower than that set in a gear shift pattern (shift map) dedicated to the sport mode when a change occurs from a driving mode other than the sport mode to the sport mode during driving. The driver's desire to enjoy dynamic driving can be satisfied.

[0013] In one aspect, a method for controlling gear shifting in response to a change in a driving mode is provided, the method comprising: (a) when a request to change the driving mode to a sport mode is detected during driving, determining a maximum number of allowable low-speed gear shifting steps based on a result of determining a transmission state based on information on an accelerator pedal operation (a signal from an APS); (b) using a current speed of an output shaft of the transmission and a gear ratio of each step, calculating an expected speed of the turbine immediately after gear shifting for each step included in the maximum number of allowable low-speed gear shifting steps, and comparing the calculated expected speed of the turbine (the speed of the input shaft of the transmission) with a preset allowable speed of the turbine for each step; (c) within the maximum number of allowable low-speed gear shifting steps, setting a lowest-level gear shifting step among the gear shifting steps in which the expected speed of the turbine and the allowable speed of the turbine satisfy predetermined conditions as a target gear shifting step; and (d) performing gear shifting control to reduce the current gear shifting step to the target gear shifting step.

[0014] The "expected turbine speed" here refers to a value obtained by anticipating the speed of the transmission input shaft directly connected to the turbine, as the expected value of the speed of the torque converter turbine arranged between the engine and the transmission. This value can be derived from a simple equation in which the current speed of the transmission output shaft (vehicle speed) is multiplied by the inverse of the gear ratio of the target shift step.

[0015] The term "allowable turbine speed" is one of the terms used to describe embodiments of the present disclosure and refers to the allowable speed of the transmission input shaft. The allowable turbine speed is the maximum speed of the transmission input shaft at which engine power can be stably output through gear shifting without sacrificing the load capacity of each gear shift step. The allowable turbine speed is a fixed value set in a recording device (such as a memory) so that it changes with each gear shift step (because the gear ratio changes with each gear shift step).

[0016] In a preferred aspect, in (a) determining the maximum number of allowable low-speed shift steps, the transmission can be determined to be in an energized state when the output of the APS is at or above a set value at a time point when a request to change the driving mode is detected, and can be determined to be in an energized state when the output of the APS is below the set value.

[0017] In a preferred aspect, when the transmission is in an energized state, the number of low-speed shift steps lower than the set shift steps determined by the sport mode-dedicated shift pattern can be determined as the maximum number of low-speed shift steps allowed, and when the transmission is in an energized state, the maximum number of low-speed shift steps allowed can be determined as 1, in this way allowing low-speed shifting to a low-speed shift step that is only one step lower than the set shift step determined by the sport mode-dedicated shift pattern (the set shift step number minus 1).

[0018] In another preferred aspect, in the method, in (b) calculating the expected speed of the turbine immediately after the gear shift, for each step, the expected speed of the turbine immediately after the gear shift may be a value obtained by dividing the current speed of the output shaft of the transmission by the gear ratio of each step (current speed of the output shaft of the transmission / gear ratio of each step).

[0019] In another preferred aspect, in the method, in (c) of setting the lowest-level shift step, the predetermined condition may be that the expected speed of the turbine does not exceed the allowable speed of the turbine.

[0020] In certain preferred aspects, the method may further include: (e) comparing the time (shift control time) used for the shift control in (d) of performing the shift control to reduce the current shift step to the target shift step with a preset shift control time.

[0021] In a preferred aspect, in the method, when the shift control time exceeds the set shift control time, the processing can be terminated in such a state without further performing the shift control, and when the shift control time is shorter than the set shift control time, it can be determined whether the shift to the target shift step is completed, and when the shift is completed within the set shift control time, the processing can be terminated.

[0022] In a preferred aspect, in the method, when the shift control time is shorter than the set shift control time and the shifting to the target shift step is not completed, it is possible to return to (d) of executing the shift control, and repeat (d) of executing the shift control and (e) of comparing the time used for the shift control.

[0023] In certain preferred aspects, the method may further include (f) executing control for restricting shifting to a higher-level shift step after completing the shifting to the target shift step.

[0024] In certain preferred aspects, in the method, (f) executing control for limiting gear shifting includes: (f-1) after completing the gear shift to the target gear shift, requesting prevention of the gear shift to the advanced gear shift step so as to limit the gear shift to the advanced gear shift step; and (f-2) comparing the current gear shift step (the gear shift step corresponding to the target gear shift step) with the set gear shift step determined by the sports mode-dedicated gear shifting pattern based on the current output of the APS and the current vehicle speed, and determining whether to cancel or maintain the prevention of the gear shift to the advanced gear shift step based on the comparison result.

[0025] In certain preferred aspects, in the method, (f-2) comparing the current shifting step with the set shifting step may include: (f-2-1) when the current shifting step (the shifting step corresponding to the target shifting step) is equal to the set shifting step or the advanced shifting step, since the control of preventing shifting to the advanced shifting step is not needed, the control of preventing shifting to the advanced shifting step is immediately canceled; and (f-2-2) when the current shifting step (the shifting step corresponding to the target shifting step) is a shifting step lower than the set shifting step, maintaining the prevention of shifting to the advanced shifting step, and determining the time point for canceling the prevention of shifting to the advanced shifting step by utilizing additional information.

[0026] In certain preferred aspects, in the method, in (f-2-2) maintaining prevention of shifting, the current engine speed can be compared with a preset allowable engine speed to prevent the engine from over-limiting; when the current engine speed is higher than the allowable engine speed, a forced shift to a higher-level shift step that is one step higher than the current shift step can be performed, and then the obtained higher-level shift step can be compared with the set shift step determined by the sports mode-dedicated shift mode based on the current output of the APS and the current vehicle speed; and when the higher-level shift step that is one step higher is higher than the set shift step, the prevention of shifting to the higher-level shift step can be canceled.

[0027] In certain preferred aspects, in the method, when (f-2-2) shift prevention is maintained, when the current engine speed is lower than the permitted engine speed, it is possible to determine whether the driver has the intention to accelerate based on the output of the APS and the time for which the output of the APS continues to be provided; when the output of the APS continues to be provided in a state equal to or higher than the set value for a set time or longer, it is possible to determine that the driver actually has the intention to accelerate, so that the timer can be operated, and at the same time, the increase in vehicle speed obtained after the time point when the shift to the current shift step is completed can be compared with a predetermined reference value for the increase in vehicle speed. values ​​are compared; when the increase in vehicle speed is equal to or higher than the reference value for the increase in vehicle speed, this situation can be identified as an increase in vehicle speed due to the slope of the road, rather than an intention to undergo acceleration, and therefore, a forced shift to a higher-level shift step that is one step higher than the current shift step can be immediately performed; and subsequently, based on the current output of the APS and the current vehicle speed, the obtained higher-level shift step can be compared with the set shift step determined by the sport-mode-dedicated shift pattern, and when the higher-level shift step that is one step higher is higher than the set shift step, prevention of shifting to the higher-level shift step can be canceled.

[0028] In certain preferred aspects, in the method, as a result of comparing an increase in vehicle speed obtained after a time point when a gear shift is completed with a reference value for vehicle speed increase, when the increase in vehicle speed is lower than the reference value for vehicle speed increase, the value of the time of the operation timer can be compared with a preset time reference value, and at a time point when the time value is higher than the time reference value, a forced shift to a higher-level gear shift step that is one step higher than the current gear shift step can be performed; and subsequently, based on a current output of the APS and a current vehicle speed, the obtained higher-level gear shift step can be compared with a set gear shift step determined by a sport-mode-dedicated gear shift pattern, and when the higher-level gear shift step that is one step higher is higher than the set gear shift step, prevention of shifting to the higher-level gear shift step can be canceled.

[0029] In certain preferred aspects, in the method, a forced shift to a higher-level shift step (a shift step corresponding to a target shift step) that is one step higher than the current shift step can be performed, and then the obtained higher-level shift step can be compared with the set shift step determined by the sports mode-dedicated shift pattern based on the current output of the APS and the current vehicle speed; as a result of the comparison, when the higher-level higher-level shift level is lower than the set shift step, a forced shift to the higher-level higher-level shift step can be performed; and subsequently, a return to comparing the obtained higher-level shift step with the set shift step can occur, and the comparison of the obtained higher-level shift step and its subsequent operations can be repeated.

[0030] One or more steps may be performed using a processor or a control unit.

[0031] According to another aspect of the present disclosure, a system for controlling gear shifting in response to a change in a driving mode is provided, the system including: a mode change switch for changing the driving mode; an accelerator position sensor (APS) configured to detect a driver's operation of an accelerator pedal and output a corresponding signal; a vehicle speed detector configured to detect the speed of an output shaft of a transmission; and a transmission control unit (TCU) configured to control the transmission based on information provided from the mode change switch, the APS, and the vehicle speed detector, wherein, when a change from a driving mode other than the sport mode to the sport mode is detected during driving, the transmission control unit performs a downshift control to a lower-level gear shift step that is one step lower than a set gear shift step determined by a sport-mode-dedicated gear shift pattern.

[0032] In certain preferred aspects, in the system, the transmission control unit may include: a shift mode change recognition unit configured to receive information about the driving mode change from the mode change switch and acquire a shift mode that matches the changed driving mode; a low-speed shift step number determination unit configured to determine the maximum number of low-speed shift steps allowed based on a result of determining the transmission state based on information about the accelerator pedal operation (APS signal) when the shift mode change recognition unit recognizes that the driving mode is changed to the sport mode during driving; and a turbine expected speed calculation unit configured to use Using the current speed of the output shaft of the transmission and the gear ratio of each step, the expected speed of the turbine after the immediate shift (the speed of the input shaft of the transmission) for each step included in the maximum number of allowed low-level shift steps is calculated; a target shift step determination unit is configured to set the lowest-level shift step among the shift steps in which the calculated expected turbine speed for each step included in the maximum number of allowed low-level shift steps and the allowed turbine preset speed for each step meet predetermined conditions as the target shift step; and a transmission controller is configured to perform shift control to reduce the shift step to the target shift step.

[0033] In certain preferred aspects, in the system, when the output of the APS is at or above a set value at a time point when a request to change the driving mode is detected, the low-level shift step number determination unit can determine that the transmission is in an energized state, and can determine the number of low-level shift steps that is lower than the set shift step determined by the sport mode-dedicated shift pattern as the maximum number of low-level shift steps allowed; and wherein, when the output of the APS is lower than the set value, the low-level shift step number determination unit can determine that the transmission is in an off-power state, and can determine the maximum number of low-level shift steps allowed to be 1, in this way allowing low-level shifting to a low-level shift step that is only one step lower than the set shift step determined by the sport mode-dedicated shift pattern (the set shift step number minus 1).

[0034] In certain preferred aspects, in the system, the turbine expected speed calculation unit can calculate the expected speed of the turbine immediately after shifting gears for each step by dividing the current speed of the transmission output shaft detected by the vehicle speed detector by the gear ratio of each step (current speed of the transmission output shaft / gear ratio of each step).

[0035] In certain preferred aspects, in the system, the predetermined condition may be a condition that the expected speed of the turbine does not exceed the allowed speed of the turbine.

[0036] In certain preferred aspects, in the system, the transmission control unit may further include a control time comparison unit configured to count the time (shift control time) used for the shift control to reduce the current shift step to the target shift step, and compare the counted shift control time with the preset shift control time, wherein, when the shift control time exceeds the set shift control time, the control time comparison unit may issue a request to the transmission controller to prevent the shift control.

[0037] In certain preferred aspects, in the system, the transmission control unit may include a shift prevention request unit configured to request the transmission controller to prevent shifting to the high-level shift step after completing the shift to the target shift step to limit the shift to the high-level shift step.

[0038] According to an embodiment of the present disclosure, when a switch from a driving mode other than Sport mode to Sport mode occurs during driving, the target shift step is set to a step lower than the shift step of the shift pattern (shift map) set to Sport mode (based on the permissible speed of the turbine at each step, the shift step that allows shifting to the lowest level). As a result, the driver can enjoy dynamic driving.

[0039] Other aspects are disclosed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and other objects, features and other advantages of the present disclosure will be more clearly understood through the following detailed description in conjunction with the accompanying drawings, in which:

[0041] Figure 1 is a schematic diagram showing a configuration of an automatic transmission vehicle including a shift control system that responds to a change in a driving mode according to an embodiment of the present disclosure;

[0042] Figure 2 is a table describing the process of setting a target shift step;

[0043] Figure 3 It is shown by Figure 1 A flowchart of a sequential shift control process sequentially executed by the shift control system in FIG. 1 ; and

[0044] Figure 4 is a flowchart of control for preventing upshifting to a high-level shifting step, which is executed immediately after a downshift is executed in response to a change of a driving mode to a sport mode during traveling. DETAILED DESCRIPTION

[0045] Preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0046] The terms used throughout this specification are only used to describe the preferred embodiments and are not intended to impose any limitations on the present disclosure. A noun in the singular has the same meaning as the plural form unless it has a different meaning in the context.

[0047] In addition, the terms "including," "having," and the like in this application are intended to indicate the presence of the features, numbers, steps, operations, constituent elements, components, or combinations thereof described in the specification. Therefore, it should be understood that the terms do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, constituent elements, components, or combinations thereof.

[0048] In addition, the terms "first", "second", etc. are used to describe various components, but should not impose any limitation on the meaning of the components. These terms are only used to distinguish one element from another.

[0049] Furthermore, the terms “unit,” “module,” etc. used throughout this specification refer to a single component that performs at least one function or operation and can be implemented by hardware, software, or a combination of both.

[0050] Furthermore, the control logic of the present disclosure may be embodied as a non-transitory computer-readable medium on a computer-readable medium containing executable program instructions executed by a processor, controller, or the like. Examples of computer-readable media include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards, and optical data storage devices. The computer-readable medium may also be distributed among network-coupled computer systems so that the computer-readable medium is stored and executed in a distributed manner, such as by a telematics server or a controller area network (CAN).

[0051] It should be understood that the term "vehicle" or "vehicular" or other similar terms used herein include general motor vehicles, such as passenger cars (including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles), watercraft (including various ships and boats), aircraft, etc., and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum). As described herein, a hybrid vehicle is a vehicle having two or more power sources, such as a gasoline-powered vehicle and an electric-powered vehicle.

[0052] Similar components are given similar reference numerals and redundant descriptions thereof are avoided. In this manner, preferred embodiments of the present disclosure are described with reference to the accompanying drawings. Detailed descriptions of technologies known in the related art will be omitted when it is determined that it is not obvious to obscure the main purpose of the present disclosure.

[0053] Main terms used to describe the preferred embodiments of the present disclosure have the following meanings.

[0054] The term "expected turbine speed" is one of the terms used to describe embodiments of the present disclosure. It refers to a value obtained by anticipating the speed of the transmission input shaft directly connected to the turbine, serving as an expected value for the speed of the torque converter turbine disposed between the engine and the transmission. This value can be derived from a simple equation in which the current speed of the transmission output shaft (vehicle speed) is multiplied by the inverse of the gear ratio of the target shift step.

[0055] The term "allowable turbine speed" is one of the terms used to describe embodiments of the present disclosure and refers to the allowable speed of the transmission input shaft. The allowable turbine speed is the maximum speed of the transmission input shaft at which engine power can be stably output through gear shifting without sacrificing the load capacity of each shift step. The allowable turbine speed is a fixed value set in a recording device (such as a memory) in such a manner that it changes with each shift step (because the transmission ratio changes with each shift step).

[0056] First, a configuration of a shift control system in response to a change in a driving mode according to an embodiment of the present disclosure is described with reference to the accompanying drawings.

[0057] Figure 1 is a schematic diagram showing a configuration of an automatic transmission vehicle including a shift control system that responds to a change in a driving mode according to an embodiment of the present disclosure.

[0058] Reference Figure 1 A shift control system 1 responsive to a driving mode change according to an embodiment of the present disclosure includes a mode change switch 10 for changing the driving mode and an accelerator position sensor (APS) 20 that detects a driver's operation of an accelerator pedal and outputs a corresponding signal. Furthermore, the shift control system 1 includes a vehicle speed detector 30 that detects the speed of the transmission's output shaft (i.e., vehicle speed) and a transmission control unit (TCU) 40.

[0059] The mode change switch 10 may be preferably installed near the driver's seat and may be configured in such a manner that a desired driving mode (e.g., one of the ECO mode, normal mode, comfort mode, and sport mode) is selected using a button or dial input method. The transmission control unit 40 controls the transmission based on information provided from the mode change switch 10, the APS 20, and the vehicle speed detector 30.

[0060] According to the present embodiment, specifically, when a change in driving mode to Sport mode is detected while driving in a driving mode other than Sport mode (e.g., ECO mode, Normal mode, or Comfort mode), the transmission control unit 40 executes a downshift to a lower shift step that is one step lower than the set shift step determined by the Sport mode-specific shift pattern (Sport mode-specific shift map) based on the current output of the APS and the current vehicle speed. As a result, the driver can enjoy more dynamic driving and feel increased vehicle responsiveness.

[0061] To this end, the transmission control unit 40 used in accordance with the present disclosure includes a plurality of processors. The plurality of processors are programmed to execute a control sequence in a step-by-step manner. When a change in driving mode to Sport mode is detected while driving in a driving mode other than Sport mode, a command sequence is executed to perform a downshift to a lower shift step that is one step lower than the set shift step determined by the Sport mode-specific shift pattern.

[0062] The plurality of processors included in the transmission control unit 40, which are programmed to execute a control sequence in a step-by-step manner, include a shift pattern change recognition unit 400 and a low-speed shift step number determination unit 410. Furthermore, the plurality of processors include a turbine expected speed calculation unit 420, a target shift step determination unit 430, and a transmission controller 440. Furthermore, the plurality of processors may further include a control time comparison unit 450 and a shift prevention request unit 460.

[0063] The shift pattern change recognition unit 400 receives information about a driving mode change from the mode change switch 10 and acquires a shift pattern that matches the changed driving mode. Then, when the shift pattern change recognition unit 400 recognizes that the driving mode has changed to the sport mode during driving, the low-speed shift step number determination unit 410 determines the maximum number of low-speed shift steps allowed based on the transmission state determined based on information about the accelerator pedal operation (a signal from the APS 20).

[0064] Specifically, at the time when a request to change the driving mode to the sport mode is detected, if the output of the APS 20 is equal to or higher than the set value (if the condition of the output of the APS 20 ≥ the set value is satisfied, that is, if the accelerator pedal is depressed), the low-speed shift step number determination unit 410 determines that the transmission is in the energized state. Then, the number of low-speed shift steps lower than the set shift step number determined by the sport-mode-dedicated shift pattern is determined as the maximum number of low-speed shift steps allowed.

[0065] For example, in a state where the transmission is powered on and the output of the APS 20 in response to the accelerator pedal operation is equal to or higher than the set value, when the set shift step determined by the sport mode-dedicated shift pattern at the time point when the request to change the driving mode to the sport mode is detected is the fifth step, the total number of lower-level shift steps below the fifth step is 4 (the fourth step, the third step, the second step, and the first step). Therefore, in this case, the low-level shift step number determination unit 410 determines to set the maximum number of allowable low-level shift steps to 4, and thus sets all the shift steps below the fifth step to be included in the target shift step list.

[0066] In contrast, when the output of the APS 20 is lower than the set value at the time when the request to change the driving mode to the sport mode is detected, the low-speed shift step number determination unit 410 determines that the transmission is in the power-off state. At the same time, the low-speed shift step number determination unit 410 determines that the maximum number of allowable low-speed shift steps is set to 1, thereby allowing downshifting to a shift step that is only one step lower than the set shift step determined by the sport-mode-dedicated shift pattern (the set shift step minus 1).

[0067] For example, in a state where the transmission is de-energized and the output of the APS 20 in response to accelerator pedal operation is therefore lower than a set value, when the set shift step determined by the sport mode-dedicated shift pattern is the fifth step, as in the above example, at the time a request to change to sport mode is detected, the maximum number of permissible low-speed shift steps is one. Therefore, downshifting to fourth gear, one step lower than fifth gear, is permitted. Downshifting to the next shift step, i.e., to third or lower gear steps, is restricted. Information regarding the maximum number of permissible low-speed shift steps is provided to the turbine expected speed calculation unit 420. Based on the provided information (information regarding the maximum permissible number of low-speed shift steps), the turbine expected speed calculation unit 420 calculates the turbine expected speed (speed of the transmission input shaft) immediately after the shift for each step within the maximum number of permissible low-speed shift steps using the current speed of the transmission output shaft and the gear ratio of each step.

[0068] Preferably, as described above, the expected speed after the turbine immediate shift for each step is derived by a simple calculation in which the current speed of the transmission output shaft (vehicle speed) is multiplied by the inverse of the gear ratio for each step included in the maximum number of permissible low-speed shift steps. That is, the expected speed after the turbine immediate shift is a value obtained by dividing the current speed of the transmission output shaft (vehicle speed) by the gear ratio for each step (current speed of the transmission output shaft / gear ratio for each step).

[0069] For each step within the maximum number of permissible low-speed shift steps, information regarding the expected turbine speed immediately after the shift is provided to the target shift step determination unit 430. The target shift step determination unit 430 compares the calculated expected turbine speed for each step within the maximum number of permissible low-speed shift steps with the preset permissible turbine speed for each step. The target shift step determination unit 430 sets the lowest-level shift step among the shift steps that satisfy predetermined conditions as the final target shift step.

[0070] The predetermined condition here can be that the expected turbine speed immediately after each gear shift step does not exceed the corresponding permissible turbine speed for each gear shift step. As described above, the permissible turbine speed refers to the maximum turbine speed at which engine power can be stably output through gear shifting without sacrificing load capacity. Therefore, if the turbine speed immediately after a gear shift (downshift) to a lower gear shift step exceeds the corresponding permissible turbine speed, a significant load is placed on the transmission.

[0071] Figure 2 This is a table required to describe the process of setting the target shift step. Figure 2 It is shown that when the transmission is powered on (output of APS 20 ≥ set value), when a request to change the driving mode to the sport mode is detected, at a time point when the current speed of the output shaft of the transmission is 2000 rpm, the set shift step determined by the sport mode-dedicated shift pattern is an example of the fifth step.

[0072] like Figure 2 As shown, in the transmission power-on state (APS 20 output ≥ set value), at the time when a request to change the driving mode to the sport mode is detected, the preset shift step determined by the sport mode-dedicated shift pattern is the fifth step. When setting the target shift step, the target shift step determination unit 430 gives the highest priority to the first step, which is the lowest shift step, among the lower-level shift steps below the fifth step. However, when the current speed of the output shaft of the transmission is used as a reference, the first step does not meet the above conditions because the expected speed of the turbine exceeds the permissible speed of the turbine.

[0073] On the other hand, the second step immediately following the first step satisfies the condition that the expected turbine speed does not exceed the permissible turbine speed (expected turbine speed < permissible turbine speed). Therefore, in this case, the target shift step determination unit 430 excludes the first step, which is the lowest-level shift step and does not satisfy the above condition, from the target shift step settings, and sets the second step, which is the lowest-level shift step among the shift steps that satisfy the above condition, as the final target shift step.

[0074] When the final target shift step is determined through this process, the transmission controller 440 performs shift control to reduce the shift step to the final target shift step. Figure 2 In the illustrated case, the transmission controller 440 performs shift control (controls the corresponding shift actuator) for switching the shift step from the fifth step to the second step.

[0075] While the transmission controller 440 is performing shift control, the control time comparison unit 450 performs the following operations: counting the time (shift control time) spent on the shift control for switching the current shift step down to the target shift step (for example, switching from the fifth step down to the second step); and comparing the counted shift control time with the preset shift control time.

[0076] In a case where the shift control time (the time taken to switch the current shift step down to the target shift step) reaches the set shift control time of the set input value but the shift control has not been completed, the control time comparison unit 450 determines that the appropriate shift time has been exceeded and issues a request to prevent the shift control to the transmission controller 440.

[0077] When the kick-down is completed through the processing sequence described above together with the change to the sport mode, it is necessary to maintain this downshift state for a predetermined time so that the driver can experience a sufficient acceleration feeling. To this end, the shift prevention request unit 460 requests the transmission controller 440 to prevent shifting to a high-level shift level so as to limit upshifting after the shift is completed.

[0078] The process of controlling shifting in response to a change in driving mode will be described in detail below to provide an understanding of the request to prevent shifting to the advanced shift step and the cancellation of the request thereby performed in cooperation with the shift prevention request unit 460 and the transmission controller 440.

[0079] Figure 3 It is shown by Figure 1 Flowchart of the sequential shift control process sequentially executed by the shift control system in FIG.

[0080] Reference Figure 3 The method for controlling gear shifting in response to a change in driving mode according to an embodiment of the present disclosure is a method for controlling a transmission when switching from a driving mode other than the sport mode to the sport mode during driving. The method begins at step S100. When a request to change the driving mode to the sport mode is detected during driving, the maximum number of low-speed gear shift steps allowed is determined based on the transmission state determined based on information on accelerator pedal operation (APS signal).

[0081] In step S100, specifically, when the output of the APS is at or above a set value at the time a driving mode change request is detected (while the accelerator pedal is held depressed to a preset level or higher), the transmission is determined to be in the energized state. Then, the number of low-speed shift steps lower than the current shift step set according to the sport-mode-dedicated shift pattern is determined as the maximum number of low-speed shift steps permitted.

[0082] For example, in a state where the transmission is powered on and the output of the APS in response to accelerator pedal operation is equal to or higher than a set value, when the set shift step determined by the sport-mode-dedicated shift pattern is the fifth step when a request to change the driving mode to the sport mode is detected, the total number of lower-level shift steps below the fifth step is four (the fourth step, the third step, the second step, and the first step). Therefore, in this case, the maximum number of permissible lower-level shift steps is set to four, and therefore all shift steps below the fifth step are set to be included in the target shift step list.

[0083] Conversely, when the output of the APS is lower than a set value (while the accelerator pedal is held down or held depressed to a level lower than a set level), the transmission is determined to be in the de-energized state. The maximum number of permissible downshift steps is set to 1, allowing a downshift to a shift step that is only one step lower than the set shift step determined by the sport-mode-dedicated shift pattern (the set number of shift steps minus 1).

[0084] For example, in a state where the transmission is de-energized and the output of the APS in response to accelerator pedal operation is below a set value, if the set shift step determined by the sport-mode-dedicated shift pattern is the fifth step at the time a request to change the driving behavior to sport mode is detected, the maximum number of permitted downshift steps is 1. Therefore, downshifting to fourth gear, one step below fifth gear, is permitted. Downshifting to third or lower gear steps is restricted.

[0085] Once the maximum number of permissible low-speed shift steps is determined in step S100, step S200 is subsequently executed. In step S200, the expected speed of the turbine for each step is calculated using the current speed of the output shaft of the transmission and the gear ratio of each step included in the maximum number of permissible low-speed shift steps. The calculated expected speed of the turbine (the expected speed of the input shaft of the transmission) is compared with a preset permissible speed of the turbine for each step.

[0086] In step S200, the expected turbine speed immediately after the gear shift is preferably derived for each step by a simple calculation in which the current speed of the transmission output shaft (vehicle speed) is multiplied by the inverse of the gear ratio for each step included in the maximum number of permissible low-speed gear shift steps. That is, the expected turbine speed immediately after the gear shift is obtained by dividing the current speed of the transmission output shaft (vehicle speed) by the gear ratio for each step (current speed of the transmission output shaft / gear ratio for each step).

[0087] Then, when the expected turbine speed for each of the maximum number of permissible low-speed shift steps is derived from the current speed of the transmission output shaft (vehicle speed), step S300 is executed. In step S300, the lowest shift step among the shift steps for which the expected turbine speed and the permissible turbine speed satisfy a predetermined condition within the maximum number of permissible low-speed shift steps is set as the target shift step. The predetermined condition here is that the expected turbine speed does not exceed the permissible turbine speed.

[0088] When the target shift step is finally determined in step S300, step S400 of shift control for switching the shift step down to the target shift step is performed. Subsequently, step S500 of comparing the time (shift control time) taken for shift control for switching the current shift step to the target shift step with the preset shift control time is performed.

[0089] Specifically, in step S500, while the above-mentioned transmission controller performs shift control, the following operations are performed: counting the time (shift control time) spent on the shift control for switching the shift step down to the target shift step (for example, switching from the fifth step down to the second step); and comparing the counted shift control time with the preset shift control time.

[0090] If the shift control time (the time required to switch the shift step down to the target shift step) reaches the set shift control time of the set input value but the shift control has not yet been completed, the set appropriate shift time has been exceeded. Therefore, in this state, the process ends without further shift control. If the set shift control time has not been exceeded, the target shift step is used to monitor whether the shift is complete (S510).

[0091] At this time, when the shift control time is equal to or shorter than the set shift control time and the shift to the target shift step is not completed, the processing can be set in the following manner, that is, returning to step S400 and repeatedly executing step S400 and subsequent steps.

[0092] When a kickdown is completed along with the change to Sport mode through the processing sequence described above, it is necessary to maintain this downshift state for a predetermined time to allow the driver to experience a sufficient sense of acceleration. To this end, a control is executed (S600) for completing the shift while simultaneously limiting the shift to a higher-level shift step. Preferably, the control for limiting upshifts is executed until a predetermined requirement condition described below is satisfied.

[0093] The control for limiting upshifting will be described in more detail below.

[0094] Figure 4 is a flowchart of control for preventing upshifting to a high-level shifting step, which is executed immediately after a downshift is executed in response to a change of a driving mode to a sport mode during traveling.

[0095] Reference Figure 4 Step S600 generally includes steps S610 and S620. In step S610, a request is made to prevent shifting in order to restrict shifting to a higher-level shift step after the shifting is completed. In step S620, after the shifting is completed, the current shift step (the shift step corresponding to the target shift step) is compared with the set shift step determined by the sport-mode-specific shift pattern based on the current output of the APS and the vehicle speed, and a decision is made based on the comparison result whether to cancel or maintain the prevention of shifting to the higher-level shift step.

[0096] Specifically, as a result of the comparison in step S620, when the current shift step is equal to the set shift step or is a high-level shift step, the control to prevent shifting to the high-level shift step needs to be canceled (S622). When the current shift step is a shift step lower than the set shift step, the time point to cancel the prevention of shifting to the high-level shift step is determined by maintaining the prevention of shifting to the high-level shift step and using additional information (S624).

[0097] When entering step S624, the current engine speed is first compared with a preset permissible engine speed to prevent engine overrun (S6240). If the current engine speed is higher than the permissible engine speed, a forced shift is executed to a higher-order shift step that is one step higher than the current shift step (the shift step corresponding to the target shift step) (S6241). The resulting higher-order shift step is then compared with a set shift step determined by the sport-mode-specific shift pattern based on the APS output and vehicle speed (S6246).

[0098] As a result, if the higher-order shift step is equal to or higher than the set shift step (as determined by the comparison in step S6246), the prevention of shifting to the higher-order shift step is immediately canceled (step S6247). If the higher-order shift step is still a lower-order shift step than the set shift step, forced shifting to the higher-order shift step is further executed (step S6248). The process then returns to step S6246, where the obtained higher-order shift step is compared with the set shift step, and step S6246 and subsequent steps are repeated.

[0099] On the other hand, if the comparison result of step S6240 indicates that the current engine speed is lower than the permitted engine speed, a determination is made as to whether the driver intends to accelerate based on the output of the APS and information regarding the duration of the APS output (S6242). In step S6242, it is preferably determined that the driver actually intends to accelerate when the output of the APS remains at or above a set value (a set value for determining whether the transmission is energized) for a predetermined period of time or longer.

[0100] When it is determined in step S6242 that the driver actually has the intention to experience acceleration (when the output of the APS continues to be provided in a state at or above a set value (the set value for determining whether the transmission is energized) for a preset time), an operation timer (a timer for determining acceleration) is operated (S6243), and at the same time, the increase in vehicle speed obtained after the time point when the shift to the current shift step is completed is compared with a predetermined reference value of the vehicle speed increase (S6244).

[0101] At this time, when the increase in vehicle speed is equal to or higher than the reference value for increase in vehicle speed, this situation is identified as an increase in vehicle speed due to the slope of the road, rather than the driver's intention to experience acceleration. Therefore, the process immediately switches to step S6241. When the increase in vehicle speed is lower than the reference value for increase in vehicle speed, the value of the timer operation timer is compared with a preset time reference value (S6245). Then, at the time point when the value of the timer is higher than the preset time reference value, the process switches to the above-mentioned step S6241.

[0102] In the prior art, when a switch from a driving mode other than Sport mode to Sport mode occurs during driving, shifts are uniformly executed based on a shift reference point determined in a Sport-mode-specific shift pattern based on current vehicle conditions (vehicle speed and pedal effort). Consequently, there is a drawback in not satisfying the driver's desire for dynamic driving.

[0103] In contrast, according to an embodiment of the present disclosure, when a switch from a driving mode other than Sport mode to Sport mode occurs during driving, the target shift step is set to a lower level than the shift step set in the Sport mode-specific shift pattern (shift map) (based on the permissible turbine speed for each step, the lowest level of shift step is permitted). Consequently, downshifts are performed over a wider range. Consequently, the driver's desire to enjoy dynamic driving can be satisfied.

[0104] The above only describes the preferred embodiments of the present disclosure. However, the present disclosure should be understood not to be limited to the preferred embodiments. All modifications, equivalents, and substitutions that do not depart from the content and gist of the present disclosure should be understood to fall within the scope of the present disclosure as defined in the appended claims.

Claims

1. A method for controlling gear shifting in response to a change in driving mode, the method comprising: (a) when a request to change the driving mode to the sport mode is detected during driving, determining a maximum number of allowable low-speed shift steps based on a result of determining a transmission state based on information on an accelerator pedal operation, the information on the accelerator pedal operation being a signal from an accelerator position sensor; (b) calculating an expected speed of the turbine immediately after the gear shift for each step using the current speed of the output shaft of the transmission and the gear ratio of each step included in the maximum number of permissible low-speed gear shift steps, and comparing the calculated expected speed of the turbine with a preset permissible speed of the turbine for each step, wherein the expected speed of the turbine is a value obtained by anticipating the speed of the input shaft of the transmission directly connected to the turbine, and the permissible speed of the turbine is the permissible speed of the input shaft of the transmission; (c) setting, within the maximum number of the allowed low-speed shift steps, a lowest-speed shift step among the shift steps in which the expected speed of the turbine and the allowed speed of the turbine satisfy predetermined conditions as a target shift step; and (d) Executing shift control to shift the current shift step down to the target shift step.

2. The method according to claim 1, wherein In (a) of determining the maximum number of allowable low-speed shift steps, the transmission is determined to be in the power-on state when the output of an accelerator position sensor is at or above a set value at a time point when a request to change the driving mode is detected, and the transmission is determined to be in the power-off state when the output of the accelerator position sensor is below the set value.

3. The method according to claim 2, wherein: When the transmission is in the power-on state, the number of low-speed shift steps lower than a set shift step is determined as the maximum number of allowable low-speed shift steps, the set shift step being determined by a sport-mode-dedicated shift pattern, and When the transmission is in the power-off state, the maximum number of allowed low-speed shift steps is determined to be 1 to allow low-speed shifting to a low-speed shift step that is only one step lower than the set shift step determined by the sport-mode-dedicated shift pattern.

4. The method according to claim 1, wherein In (b) of calculating the expected speed immediately after the turbine shift, the expected speed immediately after the turbine shift in each step is a value obtained by dividing the current speed of the output shaft of the transmission by the gear ratio in each step.

5. The method according to claim 1, wherein In (c) of providing the lowest-stage shifting step, the predetermined condition is that the expected speed of the turbine does not exceed the allowable speed of the turbine.

6. The method according to claim 1, further comprising: (e) comparing a shift control time used in the shift control for shifting the current shift step down to the target shift step in (d) of executing the shift control with a preset shift control time, When the shift control time exceeds the set shift control time, the process is terminated without further executing the shift control, and When the shift control time is shorter than the set shift control time, it is determined whether the shift to the target shift step has been completed, and when the shift has been completed within the set shift control time, the process is ended.

7. The method according to claim 6, wherein: If the shift control time is shorter than the set shift control time and the shift to the target shift step is not completed, returning to (d) of executing the shift control, and repeatedly executing (d) of executing the shift control and (e) of comparing the time taken for the shift control.

8. The method according to claim 6, further comprising: (f) After the shift to the target shift step has been completed, control is performed to restrict shifting to a higher-level shift step.

9. The method according to claim 8, wherein The control (f) for executing the limited shifting includes: (f-1) after the shift to the target shift has been completed, requesting prevention of the shift to the high-level shift step in order to restrict the shift to the high-level shift step; and (f-2) comparing the current shift step with a set shift step, the current shift step being a shift step corresponding to the target shift step, and determining whether to cancel or maintain the shift to the high-level shift step based on the comparison result, the set shift step being determined by a sport-mode-dedicated shift pattern based on a current output of an accelerator position sensor and a current vehicle speed.

10. The method according to claim 9, wherein: The step (f-2) of comparing the current shift step with the set shift step includes: (f-2-1) when the current shift step, which is the shift step corresponding to the target shift step, is equal to the set shift step or is the high-level shift step, immediately canceling the shift prevention to the high-level shift step because control to prevent the shift to the high-level shift step is not necessary; and (f-2-2) When the current shift step as the shift step corresponding to the target shift step is a shift step lower than the set shift step, prevention of shifting to the high-level shift step is maintained, and a time point for canceling prevention of shifting to the high-level shift step is determined by utilizing additional information.

11. The method according to claim 10, wherein: In the (f-2-2) to prevent shifting, the current engine speed is compared with the preset allowable engine speed to prevent the engine from overrunning. When the current engine speed is higher than the allowable engine speed, a forced shift is performed to a higher-order shift step that is one step higher than the current shift step as the shift step corresponding to the target shift step, and then the resulting higher-order shift step is compared with the set shift step determined by the sport-mode-dedicated shift pattern based on the current output of the accelerator position sensor and the current vehicle speed, and When the high-level shift step one step higher is higher than the set shift step, the shifting to the high-level shift step is canceled to prevent it.

12. The method according to claim 11, wherein When the current engine speed is lower than the allowable engine speed, determining whether the driver intends to experience acceleration based on the output of the accelerator position sensor and the time for which the output of the accelerator position sensor is continuously provided, wherein, when the output of the accelerator position sensor in a state equal to or higher than a set value is continuously provided for a set time or longer, it is determined that the driver actually has an intention to experience acceleration, and thus a timer is operated, and at the same time, an increase in vehicle speed obtained after a point in time when the shift to the current shift step is completed is compared with a predetermined reference value of increase in vehicle speed, wherein, when the increase in the vehicle speed is equal to or higher than the reference value for the increase in the vehicle speed, this situation is recognized as an increase in the vehicle speed due to a slope of a road, rather than an intention to experience acceleration, and therefore, a forced shift to the higher-order shift step that is one step higher than the current shift step that is the shift step corresponding to the target shift step is immediately performed, and wherein, the obtained high-level shift step is then compared with a set shift step determined by the sport mode-dedicated shift pattern based on the current output of the accelerator position sensor and the current vehicle speed, and when the high-level shift step that is one step higher is higher than the set shift step, shifting to the high-level shift step is canceled and prevented.

13. The method according to claim 12, wherein: As a result of comparing the increase in vehicle speed obtained after a time point when a gear shift is completed with the reference value for the increase in vehicle speed, when the increase in vehicle speed is lower than the reference value for the increase in vehicle speed, comparing the time value for operating the timer with a preset time reference value, and performing a forced shift to the higher-level gear shift step that is one step higher than the current gear shift step at a time point when the time value is higher than the time reference value, and wherein, the obtained high-level shift step is then compared with the set shift step determined by the sport mode-dedicated shift pattern based on the current output of the accelerator position sensor and the current vehicle speed, and when the high-level shift step that is one step higher is higher than the set shift step, shifting to the high-level shift step is canceled and prevented.

14. The method according to claim 11, wherein performing a forced shift to the high-level shift step that is one step higher than the current shift step as the shift step corresponding to the target shift step, and then comparing the resulting high-level shift step with the set shift step determined by the sport-mode-dedicated shift pattern based on the current output of the accelerator position sensor and the current vehicle speed, Wherein, as a result of the comparison, when the higher-level shift level is lower than the set shift step, a forced shift to the higher-level shift step is performed, and Thereafter, a return is made to compare the obtained high-level shift step with the set shift step, and the operations after comparing the obtained high-level shift step and the comparison of the obtained high-level shift step are repeated.

15. A system for controlling gear shifting in response to a change in driving mode, the system comprising: mode change switch, used to change driving modes; an accelerator position sensor configured to detect a driver's operation of an accelerator pedal and output a corresponding signal; a vehicle speed detector configured to detect a speed of an output shaft of the transmission; as well as a transmission control unit TCU configured to control the transmission based on information provided from the mode change switch, the accelerator position sensor, and the vehicle speed detector, wherein, when a change from a driving mode other than the sport mode to the sport mode is detected during traveling, the transmission control unit performs downshift control for a lower shift step one step lower than a set shift step determined by a sport-mode-dedicated shift pattern.

16. The system according to claim 15, wherein: The transmission control unit comprises: a shift pattern change recognition unit configured to receive information on a driving mode change from the mode change switch and obtain a shift pattern that matches the changed driving mode; a low-speed shift step number determination unit configured to determine a maximum number of allowable low-speed shift steps based on a result of determining the transmission state based on information on an accelerator pedal operation, when the shift mode change recognition unit recognizes that the driving mode is changed to the sport mode during traveling, the information based on the accelerator pedal operation being a signal from an accelerator position sensor; a turbine expected speed calculation unit configured to calculate an expected speed of the turbine immediately after the shift for each step using a current speed of the output shaft of the transmission and a gear ratio of each step included in the maximum number of allowable low-speed shift steps; a target shift step determination unit configured to set, as a target shift step, a lowest-level shift step among shift steps in which an expected turbine speed calculated for each step included in the maximum number of allowed low-level shift steps and a preset allowed speed of the turbine for each step satisfy a predetermined condition, the expected turbine speed being a value obtained by expecting a speed of an input shaft of a transmission directly connected to the turbine, and the allowed speed of the turbine being an allowed speed of the input shaft of the transmission; a transmission controller configured to perform shift control to shift the shift step down to the target shift step; and A shift prevention request unit is configured to request the transmission controller to prevent shifting to a high-level shift step after the shifting to the target shift step is completed, so as to restrict the shifting to the high-level shift step.

17. The system according to claim 16, wherein: When the output of the accelerator position sensor is at or above a set value at a time point when a request to change the driving mode is detected, the low-speed shift step number determination unit determines that the transmission is in an energized state, and determines the number of low-speed shift steps that is lower than the set shift steps determined by the sport-mode-dedicated shift pattern as the maximum number of allowable low-speed shift steps, and Wherein, when the output of the accelerator position sensor is lower than the set value, the low-speed shift step number determination unit determines that the transmission is in a power-off state, and determines the maximum number of allowable low-speed shift steps to 1 to allow low-speed shifting to a low-speed shift step that is only one step lower than the set shift step determined by the sport mode-dedicated shift pattern.

18. The system according to claim 16, wherein: The predetermined condition is a condition that the expected speed of the turbine does not exceed the allowable speed of the turbine.

19. The system according to claim 16, wherein: The transmission control unit further includes: a control time comparison unit configured to count a shift control time used for the shift control for shifting the current shift step down to the target shift step, and compare the counted shift control time with a preset shift control time, When the shift control time exceeds the set shift control time, the control time comparison unit sends a request to the transmission controller to prevent the shift control.

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